Commitments (Future Minimum Lease Payments for Operating Leases) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
2012	$ 226,458
2013	210,590
2014	190,225
2015	162,098
2016	135,875
Thereafter	725,709
Total	1,650,955
Related Parties [Member]
2012	4,406
2013	4,346
2014	4,257
2015	3,587
2016	3,119
Thereafter	12,555
Total	32,270
Non-Related Parties [Member]
2012	222,052
2013	206,244
2014	185,968
2015	158,511
2016	132,756
Thereafter	713,154
Total	$ 1,618,685