Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Stock-based compensation expense	$ 2.0	$ 2.2	$ 11.1	$ 12.3
Stock-based compensation expense realized tax benefits from the excess of deductible amounts over expense recognized	$ 0.1	$ 0.5	$ 0.3	$ 2.7
Additional common shares issued under deferred and stock compensation arrangements			413,806
TREASURY STOCK, AT COST:
Equity, Class of Treasury Stock [Line Items]
Treasury shares purchased			1,100,000