Stock Plans and Other Incentives - Changes in RSUs (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2016 USD ($) Employee $ / shares shares	Jun. 30, 2015 USD ($) Employee $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing stock price | $ / shares	$ 24.90	$ 22.18
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock used to settle minimum employee withholding tax obligations	32,760	41,136
Number of employees withholding tax obligations | Employee	29	28
Employee withholding tax obligations approximate amount | $	$ 701,000	$ 993,000
Common stock delivered, net	52,421	64,834