Credit Facilities Line of Credit Facilities (Details) (USD $)	Dec. 31, 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	11,900,000
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	803,455,000
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	354,203,000	181,314,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Credit Facility Totals	354,203,000	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	540,399,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Credit Facility Totals	540,399,000
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	2,609,000
Line of Credit Facility - Parent Company Revolving Credit Facility
Credit Facility Totals	2,909,000
Canada, Dollar [Member] | Line of Credit Facility Advances Outstanding [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Facility	352,700,000
Canada, Dollar [Member] | Line of Credit Facility Assets Pledged [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility - Canada Lease Warehouse Facility	538,100,000
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	$ 2,600,000