Fair Value (Details 3) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financial assets:
Loans held for sale	$ 73,055	$ 61,934	$ 56,407
Financial liabilities:
Federal funds purchased and securities sold under agreements to repurchase	287,903	221,541	280,595
Other borrowings	55,055	101,210	101,045
Fair Value.
Financial assets:
Cash and cash equivalents	593,382	417,869	589,523
Investment securities	860,806	827,517	817,317
Loans held for sale	73,055	61,934
Loans, net of allowance for loan losses	5,805,702	5,743,017	5,718,977
FDIC receivable for loss share agreements	2,615	7,150	18,619
Accrued interest receivable	16,643	16,366	15,667
Mortgage servicing rights	25,325	21,601	21,015
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage - banking related)	2,418	1,976	1,309
Financial liabilities:
Deposits	6,372,390	6,193,580	6,316,613
Federal funds purchased and securities sold under agreements to repurchase	287,903	221,541	280,595
Other borrowings	50,714	98,534	104,810
Accrued interest payable	2,489	4,311	4,282
Interest rate swap - cash flow hedge	806	856	942
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage banking related)	266	313	416
Fair Value. | Commitments to extend credit
Financial liabilities:
Off balance sheet financial instruments	31,401	14,759	19,872
Quoted Prices In Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	593,382	417,869	589,523
Investment securities	12,011	13,560	13,965
Significant Other Observable Inputs (Level 2)
Financial assets:
Investment securities	848,795	813,957	803,352
Loans held for sale	73,055	61,934	56,407
Accrued interest receivable	3,605	3,443	3,496
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage - banking related)	2,418	1,976	1,309
Financial liabilities:
Deposits	6,372,390	6,193,580	6,316,613
Federal funds purchased and securities sold under agreements to repurchase	287,903	221,541	280,595
Other borrowings	50,714	98,534	104,810
Accrued interest payable	2,489	4,311	4,282
Interest rate swap - cash flow hedge	806	856	942
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage banking related)	266	313	416
Significant Other Observable Inputs (Level 2) | Commitments to extend credit
Financial liabilities:
Off balance sheet financial instruments	31,401	14,759	19,872
Significant Unobservable Inputs (Level 3)
Financial assets:
Loans, net of allowance for loan losses	5,805,702	5,743,017	5,718,977
FDIC receivable for loss share agreements	2,615	7,150	18,619
Accrued interest receivable	13,038	12,923	12,171
Mortgage servicing rights	25,325	21,601	21,015
Carrying Amount
Financial assets:
Cash and cash equivalents	593,382	417,869	589,523
Investment securities	860,351	826,943	816,648
Loans held for sale	73,055	61,934	56,407
Loans, net of allowance for loan losses	5,749,270	5,680,688	5,634,122
FDIC receivable for loss share agreements	11,035	22,161	43,766
Accrued interest receivable	16,643	16,366	15,667
Mortgage servicing rights	25,325	21,601	21,015
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage - banking related)	2,418	1,976	1,309
Financial liabilities:
Deposits	6,667,528	6,461,045	6,576,138
Federal funds purchased and securities sold under agreements to repurchase	287,903	221,541	280,595
Other borrowings	55,055	101,210	101,045
Accrued interest payable	2,489	4,311	4,282
Interest rate swap - cash flow hedge	806	856	943
Interest rate swap - non-designated hedge	156	172	185
Other derivative financial instruments (Mortgage banking related)	$ 266	$ 313	$ 416