Leased Properties (Details Textual) (USD $)			12 Months Ended
	Dec. 31, 2011	Jun. 30, 2003	Dec. 31, 2011 Operating Lease Expense [Member]	Dec. 31, 2010 Operating Lease Expense [Member]	Dec. 31, 2009 Operating Lease Expense [Member]
Leased Properties Rent Expense (Textual) [Abstract]
Rental expense under operating leases			$ 154,500,000	$ 147,886,000	$ 153,523,000
Leased Properties (Textual) [Abstract]
Lessee construction and lease agreement		85,000,000
Purchase of property including closing costs	$ 72,814,000