Subsequent Event - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 29, 2014 Subsequent Event	Feb. 21, 2014 Subsequent Event Accelerated Share Repurchase Contract
Subsequent Event [Line Items]
Stock repurchase program, authorized amount				$ 500	$ 140
Stock purchases, shares	0.9				2.0
Stock purchases, aggregate cost	50
Payment for share repurchase	$ 50.1	$ 250.4	$ 80.2		$ 140.0