Disclosure About Fair Value of Financial Instruments - Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized gain/(loss) (in AOCL)	$ 287,000	$ (135,000)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Amount by which outstanding principal amount exceeds estimated fair value	2,022,000	2,678,000	2,309,000	2,543,000
Tax Increment Financing Bond [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	14,788,000	15,699,000
Unrealized gain/(loss) (in AOCL)	287,000	(135,000)
Ending balance	15,075,000	15,564,000
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Maturity date	Dec. 20, 2020
Amount by which outstanding principal amount exceeds estimated fair value	2,000,000
Decrease in fair value of bond if yield-to-maturity was 100 basis points higher	600,000
Increase in fair value of bond if yield-to-maturity was 100 basis points lower	600,000
Fair value of Level 3 asset	$ 15,075,000	$ 15,564,000
Discount rate (in hundredths)	10.71%