v3.8.0.1
Other Comprehensive Income and Accumulated Other Comprehensive Income (Changes in AOCI) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     $ 60 $ 62
Other comprehensive income before reclassifications     (79) (45)
Amounts reclassified from other comprehensive income     (18) (33)
Other comprehensive loss, net of tax $ (23) $ (16) (97) (78)
Ending Balance (37) (16) (37) (16)
Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (7) (10)
Other comprehensive income before reclassifications     0 1
Amounts reclassified from other comprehensive income     0 0
Other comprehensive loss, net of tax     0 1
Ending Balance (7) (9) (7) (9)
Accumulated Net Unrealized Investment Gain (Loss) [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (1) (1)
Other comprehensive income before reclassifications     0 2
Amounts reclassified from other comprehensive income     1 0
Other comprehensive loss, net of tax     1 2
Ending Balance 0 1 0 1
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     92 93
Other comprehensive income before reclassifications     (88) (51)
Amounts reclassified from other comprehensive income     (19) (33)
Other comprehensive loss, net of tax     (107) (84)
Ending Balance (15) 9 (15) 9
Accumulated Translation Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (24) (20)
Other comprehensive income before reclassifications     9 3
Amounts reclassified from other comprehensive income     0 0
Other comprehensive loss, net of tax     9 3
Ending Balance $ (15) $ (17) $ (15) $ (17)