Accounting for Uncertainty in Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Liability for unrecognized tax		$ 8.2		$ 10.5
Unrecognized tax favorable impact on effective tax rate		3.6		3.8
Accrued interest and penalties applied to uncertain tax positions		3.1	7.9
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 6.1