Income Taxes - Activities Related to Gross Unrecognized Tax Benefits (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 52.1	$ 52.5	$ 48.4
Increase in balance related to tax positions taken during current year	5.4	0.6	6.6
Decrease in balance as a result of a lapse of the applicable statues of limitations	(1.3)	(0.9)	(2.1)
Decrease in balance due to settlement with tax authorities	(32.1)	0	0
Increase in balance related to tax positions taken during prior years	0.1	0	0
Decrease in balance related to tax positions taken during prior years	0	(0.1)	(0.4)
Balance at end of period	$ 24.2	$ 52.1	$ 52.5