Non-Vested Stock Option Activity (Detail) - Stock Option [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested stock options beginning balance | shares	775,994
Granted | shares	268,538
Vested | shares	(219,872)
Forfeited | shares	(97,961)
Non-vested stock options ending balance | shares	726,699
Non-Vested Stock Options Begining Balance, Weighted Average Grant Date Fair Value | $ / shares	$ 30.47
Non-Vested Stock Options Granted, Weighted Average Grant Date Fair Value | $ / shares	37.21
Non-Vested Stock Options Vested, Weighted Average Grant Date Fair Value | $ / shares	29.55
Non-Vested Stock Options Forfeited, Weighted Average Grant Date Fair Value | $ / shares	35.38
Non-Vested Stock Options Ending Balance, Weighted Average Grant Date Fair Value | $ / shares	$ 32.58