Income Taxes - Summary of Differences In Effective Tax Rate and Federal Statutory Rate Due to State Income Taxes and Other Tax Items (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Total (loss) income before income taxes	$ (199,692)	$ (55,676)	$ 210,015	$ (545,848)
U.S. federal statutory rate	35.00%	35.00%	35.00%	35.00%
Total tax (benefit) expense at statutory rate	$ (69,892)	$ (19,487)	$ 73,505	$ (191,047)
State and local income taxes, net of federal benefit	(6,537)	(2,007)	6,591	(17,963)
Non-deductible executive compensation	296	446	436	1,128
Non-deductible transaction costs	0	4,838	0	4,838
Tax less than book equity compensation	56	44	4,808	5,374
Change in valuation allowances:
Federal net operating loss carryforwards & other	69	0	3,487	0
State net operating loss carryforwards & other	4,286	2,815	10,498	10,514
Rabbi trust and other	(508)	(620)	(1,561)	1,656
Permanent differences and other	238	266	290	331
Total (benefit) expense for income taxes	$ (71,992)	$ (13,705)	$ 98,054	$ (185,169)
Effective tax rate	36.10%	24.60%	46.70%	33.90%