Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Stock-based compensation expense	$ 1.9	$ 2.3	$ 9.1	$ 10.1
Stock-based compensation expense realized tax benefits from the excess of deductible amounts over expense recognized	$ 0.1	$ 1.0	$ 0.2	$ 2.2
Additional common shares issued under deferred and stock compensation arrangements			326,205
TREASURY STOCK, AT COST:
Equity, Class of Treasury Stock [Line Items]
Treasury shares purchased	0		1,100,000