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New Accounting Pronouncements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019	Jan. 01, 2018	Jan. 01, 2016
New Accounting Pronouncement Early Adoption [Line Items]
Accumulated earnings	$ 4,504,684,000	$ 3,443,007,000
Cumulative adjustment to accumulated earnings	20,658,939,000	18,048,487,000	$ 16,830,004,000
Distributions from equity method investments reclassified from cash flows from investing activities to cash flows from operating activities	336,925,000	$ 211,855,000	195,702,000
5.00% Senior Notes [Member]
New Accounting Pronouncement Early Adoption [Line Items]
Deb instrument, redemption premium	$ 20,000,000
Debt Instrument Interest Rate Stated Percentage	5.00%	5.00%
Accounting Standards Update 2016-01
New Accounting Pronouncement Early Adoption [Line Items]
Cumulative adjustment to accumulated earnings					$ 4,000,000
Accounting Standards Update 2016-15
New Accounting Pronouncement Early Adoption [Line Items]
Distributions from equity method investments reclassified from cash flows from investing activities to cash flows from operating activities		$ 183,900,000	166,700,000
Cash paid for acquisitions reclassified from cash used in investing activities to cash used in financing activities		24,000,000	21,000,000
Accounting Standards Update 2016-15 \| 5.00% Senior Notes [Member]
New Accounting Pronouncement Early Adoption [Line Items]
Deb instrument, redemption premium	$ 20,000,000
Debt Instrument Interest Rate Stated Percentage	5.00%
Accounting Standards Update 2016-02 \| Subsequent Event [Member] \| Minimum [Member]
New Accounting Pronouncement Early Adoption [Line Items]
Lease liability				$ 1,200,000,000
Accounting Standards Update 2016-02 \| Subsequent Event [Member] \| Maximum [Member]
New Accounting Pronouncement Early Adoption [Line Items]
Lease liability				$ 1,400,000,000
Adoption of new revenue recognition guidance [Member] \| ASU 2014-09 [Member]
New Accounting Pronouncement Early Adoption [Line Items]
Accumulated earnings		94,622,000				$ 87,900,000
Cumulative adjustment to accumulated earnings		$ 5,600,000	$ 1,100,000