Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Hedge derivative expiration period	1 month
Proceeds from the sales and maturities of securities available-for-sale	$ 69,500	$ 35,200	$ 17,600
Net realized gains on corporate debt trading securities	12
Net unrealized losses on corporate debt trading securities	$ (200)