Share-Based Compensation - Schedule of Stock Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding - Beginning Balance, Shares	448,687	727,378	812,160
Granted, Shares			5,538
Exercised, Shares	(82,228)	(77,918)	(32,610)
Cancelled, Shares	(35,988)	(200,773)	(57,710)
Expired, Shares	(100,938)
Options outstanding - Ending Balance, Shares	229,533	448,687	727,378
Number of options exercisable, Shares	229,533	195,402	273,320
Options outstanding - Beginning Balance, Weighted Average Exercise Price	$ 33.31	$ 33.81	$ 33.70
Granted, Weighted Average Exercise Price			45.89
Exercised, Weighted Average Exercise Price	24.94	24.11	24.43
Cancelled, Weighted Average Exercise Price	38.69	38.71	38.74
Expired, Weighted Average Exercise Price	31.13
Options outstanding - Ending Balance, Weighted Average Exercise Price	36.42	33.31	33.81
Number of options exercisable, Weighted Average Exercise Price	$ 36.42	$ 26.11	$ 25.54