Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Reconciliation [Line Items]
Estimated effective income tax rate	30.00%	55.00%	29.00%
Effective tax rate impacted by net tax benefit	$ 0	$ 0	$ 15,505,000
Recognized tax benefit from uncertain tax positions			31,000,000
Increase (reduction) in the available loss deduction			(15,500,000)
Valuation allowance for deferred tax assets	5,731,000	10,855,000
Deferred tax assets related to net operating losses for federal income tax purposes	$ 20,272,000	20,591,000
Ownership percentage	50.00%
Percentage increasing ownership	5.00%
Pre-tax net operating loss carryovers	$ 21,400,000
Built-in losses annual limitation	1,600,000
Interest or penalties related to unrecognized tax benefits	0	0	0
Excess tax benefits (tax deficiencies) from stock-based compensation	(1,298,000)	$ 1,098,000	$ 24,805,000
Federal [Member]
Income Tax Reconciliation [Line Items]
Deferred tax assets related to net operating losses for federal income tax purposes	14,100,000
State [Member]
Income Tax Reconciliation [Line Items]
Deferred tax assets related to net operating losses for federal income tax purposes	$ 6,200,000