Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation Allowance [Line Items]
Deferred tax assets, valuation allowance	$ 288,408	$ 662,909
Liabilities for unrecognized tax benefits	0	0	$ 0
Interest and penalty charges	0	0	$ 0
Federal
Valuation Allowance [Line Items]
Operating loss carryforwards	$ 120,300
Federal | Minimum
Valuation Allowance [Line Items]
Operating loss carryforward expiration year	2032
Federal | Maximum
Valuation Allowance [Line Items]
Operating loss carryforward expiration year	2036
State and Local Jurisdiction
Valuation Allowance [Line Items]
Operating loss carryforwards	$ 69,600
Operating loss carryforwards, valuation allowance	$ 288,400
State and Local Jurisdiction | Minimum
Valuation Allowance [Line Items]
Operating loss carryforward expiration year	2024
State and Local Jurisdiction | Maximum
Valuation Allowance [Line Items]
Operating loss carryforward expiration year	2036
Federal, State and Local Tax Jurisdictions
Valuation Allowance [Line Items]
Deferred tax assets, valuation allowance		$ 662,900
Federal and state valuation allowance established against net deferred tax assets	$ 374,500