Operating Leases - Additional Information (Details) (Leased Vehicles [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Property Subject to or Available for Operating Lease [Line Items]
Term of non-cancellable pick-up leases	1 year
Aggregate residual value guarantee	$ 62,418
Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Average pick-up lease term	28 months
Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Renewal options for non-cancellable pick-up leases, maximum	72 months
Average pick-up lease term	36 months