Fair Value Measurements Quantitiative Information about Level 3 Non-Recurring Assets (Details) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified						3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012		Mar. 31, 2013 Loans Receivable [Member] Weighted Average [Member]	Dec. 31, 2012 Loans Receivable [Member] Weighted Average [Member]	Mar. 31, 2013 Loans Receivable [Member] Minimum [Member]	Dec. 31, 2012 Loans Receivable [Member] Minimum [Member]	Mar. 31, 2013 Loans Receivable [Member] Maximum [Member]	Dec. 31, 2012 Loans Receivable [Member] Maximum [Member]	Dec. 31, 2012 Other Real Estate Owned [Member] Weighted Average [Member]	Dec. 31, 2012 Other Real Estate Owned [Member] Minimum [Member]	Dec. 31, 2012 Other Real Estate Owned [Member] Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure	$ 4,494	[1]	$ 16,797	$ 4,894	[2]
Other Real Estate Owned, Fair Value Disclosure			$ 379	$ 198	[3]
Fair Value Inputs, Discount Rate						7.00%	8.00%	0.00%	6.00%	12.00%	13.00%	8.00%	8.00%	8.00%
Fair Value Inputs, Comparability Adjustments						17.00%	23.00%	0.00%	0.00%	25.00%	59.00%	8.00%	8.00%	8.00%

[1] (1)Collateral-dependent impaired loans held at March 31, 2013 that had write-downs in fair value or whose specific reserve changed during the first three months of 2013.

[2] (1)Collateral-dependent impaired loans held at March 31, 2012 that had write-downs in fair value or whose specific reserve changed during the first three months of 2012.

[3] (2)One OREO property held at March 31, 2012 had a write-down during the first three months of 2012.