Debt - Credit Facility (Details) (USD $)	Jun. 30, 2011
Line of Credit Facility [Line Items]
Receivables program maximum capacity	$ 105,000,000
Line of credit facility, letters of credit outstanding	21,700,000
Receivables facility amount outstanding	400,000
Receivables facility, letters credit outstanding	4,600,000
Receivables facility remaining borrowing capacity	100,000,000
Line of credit facility, amount outstanding	0.00
Line of credit facility, remaining borrowing capacity	188,300,000
Line of credit facility, maximum borrowing capacity	$ 210,000,000