Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Cash paid for income taxes	$ 819	$ 1,062	$ 858
Deferred tax assets, valuation allowance	$ 584	1,466
Deferred tax assets, charitable contributions expiration date	2016
Net expense related to nondeductible equity compensation awards	$ 8,806
Net expense (benefit) resulting from adjustment for revaluation of state net operating loss carryforwards	$ 632	(1,817)	$ (2,977)
Charitable Contribution Carryforwards [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance		$ 900
Minimum [Member]
Income Tax Disclosure [Line Items]
Year federal net operating loss carryforwards begin to expire	2029
Ownership shift due to the secondary offering	50.00%
Federal Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 709,000
State Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	1,105,000
Deferred tax assets, valuation allowance	$ 600