Shareholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	2 Months Ended	12 Months Ended
	Feb. 22, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 21, 2017
Class Of Stock [Line Items]
Number of shares repurchased			5,000	294,000
Shares repurchased aggregate purchase price		$ 112,699	$ 645	$ 22,817
Subsequent Event
Class Of Stock [Line Items]
Number of shares repurchased	42,000
Shares repurchased aggregate purchase price	$ 6,200
Number of shares authorized to be repurchased					2,000,000