Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of income (loss) before income taxes
Domestic		$ 313,203	$ 224,058	$ 172,276
Foreign		(26,359)	(2,486)	6,057
Income before income taxes		286,844	221,572	178,333
Current benefit (provision):
Federal		(4,788)	(165)	(2,593)
State		(305)	(9,601)	9,006
Foreign		(2,911)	(6,303)	(5,455)
Total current benefit (provision)		(8,004)	(16,069)	958
Deferred benefit (provision):
Federal		(93,681)	(62,572)	(31,905)
State		(10,023)	4,818	(1,283)
Foreign		5,556	1,622	1,446
Total deferred provision		(98,148)	(56,132)	(31,742)
Total income tax provision, net	$ 23,200	$ (106,152)	$ (72,201)	$ (30,784)
Actual tax provision reconciliation to the amounts computed by applying statutory Federal tax rate to income (loss) before taxes
Statutory rate		35.00%	35.00%	35.00%
State income taxes, net of Federal benefit		4.60%	2.10%	(0.20%)
Permanent differences		3.20%	3.60%	0.60%
Tax credits		(6.20%)	(10.10%)	(18.60%)
Valuation allowance		0.00%	2.80%	(0.90%)
Other		0.40%	(0.80%)	1.40%
Total effective tax rate		37.00%	32.60%	17.30%
Deferred tax assets:
Net operating losses, credit and other carryforwards	178,925	$ 178,925	$ 315,924
Unrealized losses on investments, net	47,737	47,737	47,678
Accrued expenses	39,596	39,596	34,037
Stock-based compensation	14,389	14,389	13,345
Other assets	15,008	15,008	9,534
Total deferred tax assets	295,655	295,655	420,518
Valuation allowance	(75,372)	(75,372)	(72,131)
Deferred tax assets after valuation allowance	220,283	220,283	348,387
Deferred tax liabilities:
Depreciation and amortization	(962,838)	(962,838)	(993,326)
Other liabilities	(1,319)	(1,319)	(1,412)
Total deferred tax liabilities	(964,157)	(964,157)	(994,738)
Total net deferred tax liabilities	(743,874)	(743,874)	(646,351)
Deferred Taxes by classification
Noncurrent portion of net deferred tax liabilities	(743,874)	(743,874)	(646,351)
Total net deferred tax liabilities	(743,874)	(743,874)	(646,351)
Net operating loss carryforwards	351,300	351,300
Net operating loss carryforwards attributable to stock-based compensation	38,400	38,400
Undistributed earnings of foreign subsidiaries	0	0
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance as of beginning of period		62,366	44,839	$ 43,319
Additions based on tax positions related to the current year		2,132	11,748	3,806
Additions based on tax positions related to prior years		3	5,779	4,643
Reductions based on tax positions related to prior years		(734)	0	(81)
Reductions based on tax settlements		(265)	0	(6,848)
Balance as of end of period	63,502	63,502	62,366	$ 44,839
Unrecognized tax benefits if recognized, could affect our effective tax rate	63,500	63,500	$ 62,400
Foreign
Deferred Taxes by classification
Net operating loss carryforwards	115,900	115,900
Federal
Deferred Taxes by classification
Tax credit available to offset future tax liabilities	117,100	117,100
State
Deferred Taxes by classification
Tax credit available to offset future tax liabilities	$ 52,600	$ 52,600