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
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Total income (loss) before income taxes	$ 282,506	$ (135,748)
U.S. federal statutory rate	35.00%	35.00%
Total tax expense (benefit) at statutory rate	$ 98,877	$ (47,512)
State and local income taxes, net of federal benefit	8,982	(4,432)
Non-deductible executive compensation	140	236
Tax less than book equity compensation	2,524	5,266
Change in valuation allowances:
Federal net operating loss carryforwards & other	856
State net operating loss carryforwards & other	2,086	4,490
Rabbi trust	(1,122)	(51)
Permanent differences and other	52	27
Total income tax expense (benefit)	$ 112,395	$ (41,976)
Effective tax rate	39.80%	30.90%