Income Taxes (Income Tax Expense (Benefit)) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current income tax expense
State and local	$ 4,504	$ 1,678	$ 2,422
Total current income tax	4,504	1,678	2,422
Deferred tax benefit
Federal	(157,277)	(19,496)	(48,123)
State and local	(10,953)	(8,336)	(139)
Total deferred tax	(168,230)	(27,832)	(48,262)
Net income tax benefit	$ (163,726)	$ (26,154)	$ (45,840)