Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Leased Assets [Line Items]
Operating Lease Expirations, Minimum	2012
Operating Lease Expirations, Maximum	2096
Operating Leases, Future Minimum Payments Due, Current	$ 5,444,000
Operating Leases, Rent Expense	6,100,000	5,300,000	5,200,000
Operating Leases, Future Minimum Payments, Due in Two Years	4,672,000
Operating Leases, Future Minimum Payments, Due in Three Years	4,353,000
Operating Leases, Future Minimum Payments, Due in Four Years	4,224,000
Operating Leases, Future Minimum Payments, Due in Five Years	4,227,000
Operating Leases, Future Minimum Payments, Due Thereafter	188,526,000
Operating Leases, Future Minimum Payments Due	$ 211,446,000