Other Receivables (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Other Receivables
Other receivables	$ 45,425	$ 17,808
Loans to customers to finance vehicle purchases
Other Receivables
Other receivables	3,646	4,151
Capital lease receivables
Other Receivables
Other receivables	311	308
Accrued customer billings
Other Receivables
Other receivables	6,088	6,934
Fuel tax and carbon credits
Other Receivables
Other receivables	32,867	2,780
Other
Other Receivables
Other receivables	$ 2,513	$ 3,635