Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Expenses [Line Items]
Valuation allowance	$ 14,800	$ 13,000	$ 7,800
U.S. federal, net operating loss carryforwards	180,400
State net operating loss carryforwards	85,200
Excess tax benefits from stock options included in deferred tax assets for federal net operating losses	49,900
Excess tax benefits from stock options included in deferred tax assets for state net operating losses	29,500
Accumulated unremitted earnings	9,700	13,600	12,900
Unrecognized tax benefits	2,282	1,154	$ 672	$ 353
Accrued interest on income tax expense	$ 200	$ 100
Maximum [Member] | State [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2036
Maximum [Member] | Federal [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2036
Minimum [Member] | State [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2017
Minimum [Member] | Federal [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2022