Income Taxes (As Restated) - Additional Information (Detail) - USD ($) $ / shares in Units, $ 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 expense (benefit)	$ (15,234)	$ 55,084	$ 110,379	$ (106,189)	$ (91,056)	$ (54,630)	$ 23,120	$ (18,670)	$ 44,040	$ (141,236)	$ (9,012)
Valuation allowance should have been higher	346,199				2,999				346,199	2,999	3,096
Reduction in net deferred tax assets balance	0				(108,050)				0	(108,050)
Increase to net deferred tax liabilities	4,774				0				4,774	0
Increase in accumulated deficit	621,804				(212,054)				621,804	(212,054)
Net loss increased	(42,074)	213,267	489,963	$ 172,702	117,135	$ 76,928	$ 38,119	$ 31,008	$ 833,858	$ 263,190	$ 110,328
Increase in loss per share									$ 23.18	$ 7.00	$ 2.93
Total operating loss carryforwards	294,600								$ 294,600
Net operating loss carryforwards	112,600								112,600
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
Expiration date of tax credit carryforwards									Dec. 31, 2036
Restatement Adjustment [Member] | Deferred Tax Asset Valuation Allowance Adjustments [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	(64,300)	$ 111,400	$ 257,600						$ 304,700
Valuation allowance should have been higher	304,700								304,700
Reduction in net deferred tax assets balance	299,926								299,926
Increase to net deferred tax liabilities	4,774								4,774
Increase in accumulated deficit	$ 304,700								304,700
Net loss increased									$ 304,700
Increase in loss per share									$ 8.47