Condensed Consolidating Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	$ 226,148	$ 196,362	$ 547,605	$ 645,362
Net cash used in investing activities	(47,232)	(167,332)	(102,878)	(226,466)
Net cash provided by (used in) financing activities	14,205	(30,207)	(184,246)	(94,439)
Increase (decrease) in cash and equivalents	193,121	(1,177)	260,481	324,457
Cash and equivalents at beginning of period	908,843	1,052,666	841,483	727,032
Cash and equivalents at end of period	1,101,964	1,051,489	1,101,964	1,051,489
Parent
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities			126,267	282,918
Net cash used in investing activities			(48,799)	(143,427)
Net cash provided by (used in) financing activities			220,346	196,242
Increase (decrease) in cash and equivalents			297,814	335,733
Cash and equivalents at beginning of period			766,685	636,877
Cash and equivalents at end of period	1,064,499	972,610	1,064,499	972,610
Guarantors
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities			434,450	358,657
Net cash used in investing activities			(50,975)	(81,983)
Net cash provided by (used in) financing activities			(405,184)	(297,596)
Increase (decrease) in cash and equivalents			(21,709)	(20,922)
Cash and equivalents at beginning of period			54,677	81,976
Cash and equivalents at end of period	32,968	61,054	32,968	61,054
Combined Non-Guarantors
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities			(17,762)	52
Net cash used in investing activities			(7,006)	(3,935)
Net cash provided by (used in) financing activities			9,144	13,529
Increase (decrease) in cash and equivalents			(15,624)	9,646
Cash and equivalents at beginning of period			20,121	8,179
Cash and equivalents at end of period	$ 4,497	$ 17,825	4,497	17,825
Consolidating Adjustments
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities			4,650	3,735
Net cash used in investing activities			3,902	2,879
Net cash provided by (used in) financing activities			$ (8,552)	$ (6,614)