Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Income tax benefit	$ (49,069)	$ 56,357	$ 147,183	$ 106,189	$ 91,056	$ 54,630	$ (23,120)	$ 18,670	$ 260,660	$ 141,236	$ 9,012
Amount of gross deferred tax assets expected to be realized	100,000								100,000
Valuation allowance recorded in period									38,500	0
Total operating loss carryforwards	294,600								294,600
Net operating loss carryforwards	112,600								$ 112,600
Expiration date of tax credit carryforwards									Dec. 31, 2036
Unrecognized tax benefits that would impact effective tax rate if recognized	2,900				8,300				$ 2,900	8,300
Interest and penalties expense for unrecognized tax benefits liability									(2,400)	200	$ 1,800
Accrued interest and penalties on unrecognized tax benefits liability	4,000				$ 6,400				$ 4,000	$ 6,400
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of net operating loss carryforwards									Dec. 31, 2028
Minimum [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination									2012
Minimum [Member] | Various States [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination									2001
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of net operating loss carryforwards									Dec. 31, 2036
Maximum [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination									2016
Maximum [Member] | Various States [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination									2016
Capital Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	8,200								$ 8,200
Expiration date of tax credit carryforwards									Dec. 31, 2021
Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 3,700								$ 3,700