Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized share-based compensation awards	$ 0.4	$ 0.5	$ 1.3	$ 1.2
Weighted-average fair value of stock options granted			$ 4.53	$ 6.92
Expected Volatility Rate			45.00%	56.00%
Expected Term Period			6 years 4 months 24 days	6 years 2 months 12 days
Risk-Free Interest Rate			1.90%	2.20%
Expected dividend rate			2.30%	1.60%
Cash received from employees and directors stock option exercised			$ 0.1	$ 0.9
Intrinsic value of option exercised			$ 0.2	$ 1.5
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of restricted stock unit granted			$ 9.48	$ 14.41