Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount
Income tax provision (benefit) calculated using the federal statutory income tax rate	$ (532,121)	$ (2,214,094)	$ 357,895
State income taxes, net of federal income tax benefit	(25,351)	(117,624)	25,368
Impairment of goodwill with no related tax basis	0	363,666	0
Tax shortfall on stock-based compensation deduction	9,557	0	0
Valuation allowance	2,910	33,600	0
Other	835	(6,082)	3,803
Total income tax expense (benefit)	$ (544,170)	$ (1,940,534)	$ 387,066