Financial Guarantees - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Financial Guarantees [Line Items]
Term of standby letters of credit, years	1 year
Notional amount of standby letters of credit	$ 68.7	$ 62.0
Carrying value of letters of credit	0.4	0.4
Interest rate swap, notional amount	539.5	464.5
Interest Rate Swap [Member]
Financial Guarantees [Line Items]
Interest rate swap, notional amount	$ 8.0