Leases (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Credit risk profile by creditworthiness category of direct financing lease receivables
Credit risk profile by creditworthiness category of direct financing lease receivables, Total	$ 428,142	$ 379,952
Very low risk to low risk [Member]
Credit risk profile by creditworthiness category of direct financing lease receivables
Credit risk profile by creditworthiness category of direct financing lease receivables, Total	193,123	121,836
Moderate [Member]
Credit risk profile by creditworthiness category of direct financing lease receivables
Credit risk profile by creditworthiness category of direct financing lease receivables, Total	177,400	190,070
Moderately high to High risk [Member]
Credit risk profile by creditworthiness category of direct financing lease receivables
Credit risk profile by creditworthiness category of direct financing lease receivables, Total	$ 57,619	$ 68,046