Fair Value Quantitative Information about Level 3 Fair Value Measurements (Details) (Level 3, USD $) In Thousands, unless otherwise specified													6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Recurring Basis	Dec. 31, 2011 Recurring Basis	Jun. 30, 2012 Nonrecurring Basis		Dec. 31, 2011 Nonrecurring Basis	Jun. 30, 2012 Agricultural Portfolio Segment Nonrecurring Basis		Jun. 30, 2012 Residential Portfolio Segment Nonrecurring Basis		Jun. 30, 2012 Consumer Portfolio Segment Nonrecurring Basis		Jun. 30, 2012 Z-Tranche Securities Recurring Basis	Jun. 30, 2012 Z-Tranche Securities Minimum Recurring Basis	Jun. 30, 2012 Z-Tranche Securities Maximum Recurring Basis	Jun. 30, 2012 Z-Tranche Securities Weighted Average Recurring Basis	Jun. 30, 2012 Commercial Commercial Portfolio Segment Nonrecurring Basis		Jun. 30, 2012 Commercial Real Estate Commercial Portfolio Segment Nonrecurring Basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Securities available for sale	$ 3,134	$ 3,134	$ 3,243										$ 3,134
Collateral dependent impaired loans				80,208		94,961	13,437	[1]	5,874	[1]	3,322	[1]					6,979	[1]	50,596	[1]
Other real estate owned				$ 37,941	[1]	$ 44,387
Pretax discount rate													15.00%
Actual defaults														13.94%	20.94%	15.52%
Actual deferrals														6.30%	23.71%	11.32%

[1] Not Meaningful. Third party appraisals are obtained as to the value of the underlying asset, but disclosure of this information would not provide meaningful information, as the range will vary widely from loan to loan. Types of discounts considered included age of the appraisal, local market conditions, current condition of the property, and estimated sales costs. These discounts will also vary from loan to loan, thus providing range would not be meaningful.