Summary of Significant Accounting Policies - Additional Information 2 (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Counterparty	Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]
Bank over draft balance included in Accounts Payable	$ 50.2	$ 44.6
Gain loss as a result of the discontinuance of hedge accounting treatment for derivatives	3.9
Allowance for uncollectible receivables	2.5	2.4
Net derivative asset	$ 11.7
Number of counterparties	2
Number of secured lenders not in banking credit facility	2
Financial Institution
Summary Of Significant Accounting Policies [Line Items]
Number of counterparties	13