Income Taxes - Components of Net Deferred Tax Asset (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred federal income tax asset:
Net operating loss carryforward	$ 2,104,944	$ 2,102,482	$ 2,098,597
Accruals and reserves	2,177	3,481	4,531
Derivative liability		19,117
Restricted stock grants	157	160
As filed adjustments			214
Net unrealized loss on investments	23	16
Capital loss carryforward	52,475	52,490	52,603
Total deferred federal income tax asset	2,159,776	2,177,746	2,155,945
Deferred federal income tax liabilities:
Net unrealized gain on investments			154
Losses and loss adjustments expense	500	411	102
Derivative asset	51,407
Total deferred federal income tax liabilities	51,907	411	256
Less: Valuation allowance	2,107,869	2,177,335	2,155,689
Net deferred federal income tax asset	$ 0	$ 0	$ 0