Stockholders' Equity - Summary of Shares Repurchased Under Stock Purchase Program (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016	Dec. 31, 2014
Summary Of Shares Repurchased Under Stock Purchase Program [Abstract]
Number of shares repurchased	100,000	28,447
Average price of shares repurchased	$ 55.23	$ 58.19
Shares remaining to be repurchased	150,000	166,276	150,000	194,723