Related Party Transactions - Additional Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Related Party Transaction [Line Items]
Reimbursement Agreements Termination Period	90 days
Insurance Program Renewal Period	5 years
Insurance Program Renewal Term Period	January 31, 2012 through January 31, 2017
Reimbursements [Member]
Related Party Transaction [Line Items]
Total amount paid (reimbursed)	$ 6.1	$ 13.3
Partial Pre Payment For Premiums Related To D And O Insurance Program		14.6
Costs reimbursed by related party		1.4
Receivable from Affiliate	$ 0		$ 0.3