Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
ASSETS
SECURITIES HELD TO MATURITY	$ 188,450	$ 204,956
Held-to-maturity Securities, Fair Value	196,199	211,494
LOANS, NET OF ALLOWANCE FOR LOAN LOSSES	3,932,386	3,746,130
TIME CERTIFICATES OF DEPOSITS [Member]
LIABILITIES
Financial Liabilities, Book Value	639,535	630,162
Accrued Liabilities, Fair Value Disclosure		639,333
FEDERAL HOME LOAN BANK ADVANCES [Member]
LIABILITIES
Financial Liabilities, Book Value	189,522	229,701
Accrued Liabilities, Fair Value Disclosure		233,880
WHOLESALE AND CUSTOMER REPURCHASE AGREEMENTS [Member]
LIABILITIES
Financial Liabilities, Book Value	194,838	216,128
Accrued Liabilities, Fair Value Disclosure		219,857
JUNIOR SUBORDINATED DEBENTURES [Member]
LIABILITIES
Financial Liabilities, Book Value	61,857	61,857
Accrued Liabilities, Fair Value Disclosure		60,620
SUBORDINATED DEBENTURES [Member]
LIABILITIES
Financial Liabilities, Book Value	30,000	30,000
Accrued Liabilities, Fair Value Disclosure		27,217
U.S. Treasury Securities [Member]
ASSETS
SECURITIES HELD TO MATURITY	1,014	1,014
Held-to-maturity Securities, Fair Value	1,138	1,117
Agency Mortgage-Backed Securities [Member]
ASSETS
SECURITIES HELD TO MATURITY	91,385	109,553
Held-to-maturity Securities, Fair Value	96,273	113,959
Agency Collateralized Mortgage Obligations [Member]
ASSETS
SECURITIES HELD TO MATURITY	81,147	77,804
Held-to-maturity Securities, Fair Value	83,714	80,298
State County and Municipal Securities [Member]
ASSETS
SECURITIES HELD TO MATURITY	1,939	3,576
Held-to-maturity Securities, Fair Value	1,953	3,610
Single Issuer Trust Preferred Securities Issued by Banks [Member]
ASSETS
SECURITIES HELD TO MATURITY	7,957	8,000
Held-to-maturity Securities, Fair Value	7,937	7,346
Corporate Debt Securities [Member]
ASSETS
SECURITIES HELD TO MATURITY	5,008	5,009
Held-to-maturity Securities, Fair Value	5,184	5,164
Loans Net Of Allowance For Loan Loses [Member]
ASSETS
LOANS, NET OF ALLOWANCE FOR LOAN LOSSES	3,932,386	3,746,130
Loans Receivable, Fair Value Disclosure		3,807,938
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
ASSETS
Loans Receivable, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | TIME CERTIFICATES OF DEPOSITS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | FEDERAL HOME LOAN BANK ADVANCES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | WHOLESALE AND CUSTOMER REPURCHASE AGREEMENTS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | JUNIOR SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency Mortgage-Backed Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency Collateralized Mortgage Obligations [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | State County and Municipal Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Single Issuer Trust Preferred Securities Issued by Banks [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Debt Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Other Observable Inputs (Level 2) [Member]
ASSETS
Loans Receivable, Fair Value Disclosure
Significant Other Observable Inputs (Level 2) [Member] | TIME CERTIFICATES OF DEPOSITS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	644,674
Significant Other Observable Inputs (Level 2) [Member] | FEDERAL HOME LOAN BANK ADVANCES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	185,902
Significant Other Observable Inputs (Level 2) [Member] | WHOLESALE AND CUSTOMER REPURCHASE AGREEMENTS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Significant Other Observable Inputs (Level 2) [Member] | JUNIOR SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	57,218	60,620
Significant Other Observable Inputs (Level 2) [Member] | SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value	1,138	1,117
Significant Other Observable Inputs (Level 2) [Member] | Agency Mortgage-Backed Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value	96,273	113,959
Significant Other Observable Inputs (Level 2) [Member] | Agency Collateralized Mortgage Obligations [Member]
ASSETS
Held-to-maturity Securities, Fair Value	83,714	80,298
Significant Other Observable Inputs (Level 2) [Member] | State County and Municipal Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value	1,953	3,610
Significant Other Observable Inputs (Level 2) [Member] | Single Issuer Trust Preferred Securities Issued by Banks [Member]
ASSETS
Held-to-maturity Securities, Fair Value	7,937	7,346
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value	5,184	5,164
Significant Unobservable Inputs (Level 3) [Member]
ASSETS
Loans Receivable, Fair Value Disclosure	3,938,702	3,807,938
Significant Unobservable Inputs (Level 3) [Member] | TIME CERTIFICATES OF DEPOSITS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure		639,333
Significant Unobservable Inputs (Level 3) [Member] | FEDERAL HOME LOAN BANK ADVANCES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure		233,880
Significant Unobservable Inputs (Level 3) [Member] | WHOLESALE AND CUSTOMER REPURCHASE AGREEMENTS [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	197,095	219,857
Significant Unobservable Inputs (Level 3) [Member] | JUNIOR SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure
Significant Unobservable Inputs (Level 3) [Member] | SUBORDINATED DEBENTURES [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	25,954	27,217
Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Unobservable Inputs (Level 3) [Member] | Agency Mortgage-Backed Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Unobservable Inputs (Level 3) [Member] | Agency Collateralized Mortgage Obligations [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Unobservable Inputs (Level 3) [Member] | State County and Municipal Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Unobservable Inputs (Level 3) [Member] | Single Issuer Trust Preferred Securities Issued by Banks [Member]
ASSETS
Held-to-maturity Securities, Fair Value
Significant Unobservable Inputs (Level 3) [Member] | Corporate Debt Securities [Member]
ASSETS
Held-to-maturity Securities, Fair Value