Mergers and Acquisitions (Details 5) (USD $)	12 Months Ended		0 Months Ended		2 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Oct. 27, 2010 CBT item	Jan. 29, 2010 CBT item	Jun. 30, 2010 CBT item	Dec. 31, 2010 CBT	Dec. 31, 2012 CBT
Mergers and Acquisitions
Number of locations operated				38
Number of branches operated				36
Number of production offices operated				1
Number of trust offices operated				1
Discount received on the assets acquired				$ 158,000,000
Percentage of loan and foreclosed real estate losses covered by FDIC				80.00%
Maximum amount of loan and foreclosed real estate losses covered by FDIC				233,000,000
Percentage of loan and foreclosed real estate losses covered by FDIC that exceeds specified amount				95.00%
Period of loss sharing and bank reimbursement to FDIC applicable to single family assets (loans and OREO)				10 years
FDIC loss sharing period applicable to commercial assets (loans and OREO)				5 years
Period of bank reimbursement to FDIC applicable to commercial assets (loans and OREO)				8 years
FDIC loss sharing period applicable to single family loans				10 years
Period of bank reimbursement to FDIC applicable to single family loans				10 years
Number of bank facilities acquired			7
Appraised value of facilities acquired			10,900,000
Value of furniture or equipment purchased			700,000
Number of locations retained by the bank related to which furniture or equipments were purchased			27
Number of branches closed					10
Number of trust office closed by the entity					1
Pre-tax gain on acquisition	16,529,000	98,081,000				98,100,000
Merger-related expense						5,500,000
Excess of actual losses over current estimated losses required for elimination of "true-up"							$ 19,000,000