Disclosure About Fair Value of Financial Instruments - Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized gain/(loss) (in AOCL)	$ (234)	$ 177	$ (293)
Amount by which outstanding principal amount exceeds estimated fair value	(2,308)	(2,543)
Tax Increment Financing Bond [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	15,699	16,871
Principal repayments	(1,145)	(995)
Unrealized gain/(loss) (in AOCL)	234	(177)
Ending balance	14,788	15,699
Maturity date	Dec. 20, 2020
Amount by which outstanding principal amount exceeds estimated fair value	2,308
Decrease in fair value of bond if yield-to-maturity was 100 basis points higher	600
Increase in fair value of bond if yield-to-maturity was 100 basis points lower	$ 600