Income Taxes - Components of the Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (68,601)	$ 60,079	$ 21,632
State and local	515	6,322	6,702
Foreign	2,742	2,034	1,235
Total current expense (benefit)	(65,344)	68,435	29,569
Deferred:
Federal	(10,370)	82,455	149,583
State and local	8,760	3,691	6,031
Total deferred expense (benefit)	(1,610)	86,146	155,614
Total income tax expense (benefit)	$ (66,954)	$ 154,581	$ 185,183