Income Tax Provision - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rates	10.20%	33.90%
Federal income tax rate	35.00%	35.00%
Excess tax benefit	$ 10,100	$ 1,200
Income tax payments	$ 161	$ 71