Credit Facilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Credit Facilities Summary [Line Items]
Line of Credit Facility, Amount Outstanding	$ 2,719,134	$ 354,203
U.S. Dollar [Member]
Credit Facilities Summary [Line Items]
Line of Credit Facilty -Syndicated warehouse facility	2,500,000
Line of Credit Facilty - U.S. Lease Warehouse Facility	1,200,000
Line of Credit Facility - Canada Lease Warehouse Facility	787,440
Line of Credit Facility - US FLoorplan facility	1,000,000
U.S. Dollar [Member] | Line of Credit Facility Advances Outstanding [Member]
Credit Facilities Summary [Line Items]
Line of Credit Facilty -Syndicated warehouse facility	948,272
Line of Credit Facilty - U.S. Lease Warehouse Facility	863,721
Line of Credit Facility - Canada Lease Warehouse Facility	407,141	354,203
Line of Credit Facility - US FLoorplan facility	500,000
Credit Facility Totals	$ 2,719,134	$ 354,203