Operating Leases (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Operating Leases, Future Minimum Payments Receivable [Abstract]
Operating Leases, Future Minimum Payments Receivable, Current	$ 459,966
Operating Leases, Future Minimum Payments Receivable, in Two Years	436,239
Operating Leases, Future Minimum Payments Receivable, in Three Years	399,759
Operating Leases, Future Minimum Payments Receivable, in Four Years	347,574
Operating Leases, Future Minimum Payments Receivable, in Five Years	283,268
Operating Leases, Future Minimum Payments Receivable, Thereafter	$ 1,099,690