Credit Facilities Line of Credit Facilities (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Line of Credit Facility [Line Items]
Line of Credit Facilty - Canada Lease Warehouse Canadian Dollars New	$ 800,000,000
Amount of Cash Collected on Finance Receivables Pledged Excluded from Restricted Cash Pledged	29,100,000
U.S. Dollar [Member]
Line of Credit Facility [Line Items]
Line of Credit Facilty -Syndicated warehouse facility	2,500,000,000
Line of Credit Facilty - U.S. Lease Warehouse Facility	600,000,000
Line of Credit Facility - Canada Lease Warehouse Facility	588,553,000
Line of Credit Facility - Parent Company Revolving Credit Facility	300,000,000
U.S. Dollar [Member] | Line of Credit Facility Advances Outstanding [Member]
Line of Credit Facility [Line Items]
Line of Credit Facilty -Syndicated warehouse facility		621,257,000
Line of Credit Facilty - U.S. Lease Warehouse Facility
Line of Credit Facility - Canada Lease Warehouse Facility	308,033,000	181,314,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Line of Credit Facility - Medium-term note facility	215,202,000	293,528,000
Credit Facility Totals	523,235,000	1,099,391,000
U.S. Dollar [Member] | Line of Credit Facility Assets Pledged [Member]
Line of Credit Facility [Line Items]
Line of Credit Facilty -Syndicated warehouse facility
Line of Credit Facilty - U.S. Lease Warehouse Facility
Line of Credit Facility - Canada Lease Warehouse Facility	477,518,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Line of Credit Facility - Medium-term note facility	236,252,000
Credit Facility Totals	713,770,000
U.S. Dollar [Member] | Line of Credit Faciltiy Restricted Cash Pledged [Member]
Line of Credit Facility [Line Items]
Line of Credit Facilty -Syndicated warehouse facility	300,000
Line of Credit Facilty - U.S. Lease Warehouse Facility
Line of Credit Facility - Canada Lease Warehouse Facility	2,267,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Line of Credit Facility - Medium-term note facility	83,683,000
Credit Facility Totals	86,250,000
Canada, Dollar [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Canadian Dollar	600,000,000
Canada, Dollar [Member] | Line of Credit Facility Advances Outstanding [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Facility	314,000,000
Canada, Dollar [Member] | Line of Credit Facility Assets Pledged [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Facility	486,800,000
Canada, Dollar [Member] | Line of Credit Faciltiy Restricted Cash Pledged [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Facility	$ 2,300,000