Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stockholders Equity Note [Line Items]
Stock-based compensation expense	$ 7.5	$ 5.8
Stock-based compensation expense realized tax benefits from the excess of deductible amounts over expense recognized	$ 1.3	$ 0.7
Additional common shares issued under deferred and stock compensation arrangements	406,457