Fair Value Accounting and Measurement Fair Value Accounting and Measurement (Carrying Amounts and Estimated Fair Values of Selected Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Assets
Interest-earning deposits with banks	$ 389,353	$ 202,925
Securities available for sale	1,001,665	1,028,110
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Assets
Cash and due from banks	124,573	91,364
Interest-earning deposits with banks	389,353	202,925
Securities available for sale	1,001,665	1,028,110
FHLB stock	21,819	22,215
Loans held for sale	2,563	2,148
Loans	2,864,803	2,827,259
FDIC loss-sharing asset	96,354	175,071
Interest rate contracts	14,921	16,302
Liabilities
Deposits	4,042,085	3,815,529
FHLB Advances	6,644	119,009
Repurchase agreements	25,000	25,000
Interest rate contracts	14,921	16,302
Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and due from banks	124,573	91,364
Interest-earning deposits with banks	389,353	202,925
Securities available for sale	1,001,665	1,028,110
FHLB stock	21,819	22,215
Loans held for sale	2,563	2,148
Loans	2,944,317	2,957,345
FDIC loss-sharing asset	26,543	71,788
Interest rate contracts	14,921	16,302
Liabilities
Deposits	4,043,221	3,817,013
FHLB Advances	5,894	119,849
Repurchase agreements	26,464	26,580
Interest rate contracts	14,921	16,302
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and due from banks	0
Interest-earning deposits with banks	0
Securities available for sale	981,837
FHLB stock	21,819
Loans held for sale	2,563
Loans	0
FDIC loss-sharing asset	0
Interest rate contracts	14,921
Liabilities
Deposits	493,400
FHLB Advances	5,894
Repurchase agreements	26,464
Interest rate contracts	14,921
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and due from banks	0
Interest-earning deposits with banks	0
Securities available for sale	0
FHLB stock	0
Loans held for sale	0
Loans	2,944,317
FDIC loss-sharing asset	26,543
Interest rate contracts	0
Liabilities
Deposits	0
FHLB Advances	0
Repurchase agreements	0
Interest rate contracts	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and due from banks	124,573
Interest-earning deposits with banks	389,353
Securities available for sale	19,828
FHLB stock	0
Loans held for sale	0
Loans	0
FDIC loss-sharing asset	0
Interest rate contracts	0
Liabilities
Deposits	3,549,821
FHLB Advances	0
Repurchase agreements	0
Interest rate contracts	$ 0