v3.7.0.1
Fair Value Measurements (Schedule Of Fair Value, Assets And Liabilities Measured On Recurring Basis) (Details) - USD ($)
$ in Millions
Jun. 30, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Net, Current $ 145  
Risk Management Assets, Net, Long-term 135 $ 16
Risk Management Liabilities, Net, Current 42 254
Risk Management Liabilities, Net, Long-term 13 35
Guarantor Obligations, Current Carrying Value 16 19
Accounts Payable and Accrued Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value 5 5
Risk Management Liabilities, Gross Assets
Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value 11 14
Risk Management Liabilities, Gross Assets
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value
Level 1 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value 5 5
Level 2 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value 11 14
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value
Level 3 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Guarantor Obligations, Current Carrying Value
Commodity Contract [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 159 11
Risk Management Assets, Net, Current 129  
Risk Management Assets, Gross Liabilities (30) (11)
Commodity Contract [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 141 19
Risk Management Assets, Net, Long-term 126 16
Risk Management Assets, Gross Liabilities (15) (3)
Commodity Contract [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities 72 264
Risk Management Liabilities, Net, Current 42 253
Risk Management Liabilities, Gross Assets (30) (11)
Commodity Contract [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities 28 38
Risk Management Liabilities, Net, Long-term 13 35
Risk Management Liabilities, Gross Assets (15) (3)
Commodity Contract [Member] | Level 1 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets
Commodity Contract [Member] | Level 1 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets
Commodity Contract [Member] | Level 1 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities
Commodity Contract [Member] | Level 1 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities
Commodity Contract [Member] | Level 2 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 128 11
Commodity Contract [Member] | Level 2 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 141 19
Commodity Contract [Member] | Level 2 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities 72 228
Commodity Contract [Member] | Level 2 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities 28 38
Commodity Contract [Member] | Level 3 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 31
Commodity Contract [Member] | Level 3 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets
Commodity Contract [Member] | Level 3 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities 36
Commodity Contract [Member] | Level 3 [Member] | Other Liabilities and Provisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities
Foreign Exchange Contract [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 16  
Risk Management Assets, Net, Current 16  
Foreign Exchange Contract [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 9  
Risk Management Assets, Net, Long-term 9  
Foreign Exchange Contract [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities   1
Risk Management Liabilities, Net, Current   1
Foreign Exchange Contract [Member] | Level 1 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets  
Foreign Exchange Contract [Member] | Level 1 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets  
Foreign Exchange Contract [Member] | Level 1 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities  
Foreign Exchange Contract [Member] | Level 2 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 16  
Foreign Exchange Contract [Member] | Level 2 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets 9  
Foreign Exchange Contract [Member] | Level 2 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities   1
Foreign Exchange Contract [Member] | Level 3 [Member] | Other Current Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets  
Foreign Exchange Contract [Member] | Level 3 [Member] | Other Noncurrent Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Assets, Gross assets  
Foreign Exchange Contract [Member] | Level 3 [Member] | Other Current Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Risk Management Liabilities, Gross liabilities