Fair Value of Assets and Liabilities (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financial assets
Cash and cash equivalents	$ 187,040	$ 128,032
Investment securities, available-for-sale	3,683,005	3,126,743
Loans held for sale	145,501	95,457
Loans receivable, net of ALLL	3,266,571	3,328,619
Accrued interest receivable	37,770	34,961
Non-marketable equity securities	48,812	49,694
Total financial assets	7,368,699	6,763,506
Financial liabilities
Deposits	5,364,461	4,821,213
FHLB advances	997,013	1,069,046
Repurchase agreements and other borrowed funds	299,540	268,638
Subordinated debentures	125,418	125,275
Accrued interest payable	4,675	5,825
Interest Rate Swaps	16,832	8,906
Total financial liabilities	6,807,939	6,298,903
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets
Cash and Cash Equivalents, Fair Value Disclosure	187,040	128,032
Loans Held-for-sale, Fair Value Disclosure	145,501	95,457
Accrued interest receivable, Fair Value Disclosure	37,770	34,961
Total financial assets	370,311	258,450
Financial liabilities
Deposits, Fair Value Disclosure	3,585,126	3,132,261
Accrued interest payable, Fair Value Disclosure	4,675	5,825
Total financial liabilities	3,589,801	3,138,086
Significant Other Observable Inputs (Level 2) [Member]
Financial assets
Available-for-sale Securities, Fair Value Disclosure	3,683,005	3,126,743
Loans Receivable, net of ALLL, Fair Value Disclosure	3,184,987	3,146,502
Non-marketable equity securities, Fair Value Disclosure	48,812	49,694
Total financial assets	6,916,804	6,322,939
Financial liabilities
Deposits, Fair Value Disclosure	1,789,134	1,698,382
FHLB advances, Fair Value Disclosure	1,027,101	1,099,699
Repurchase agreements and other borrowed funds, Fair Value Disclosure	299,540	268,642
Subordinated debentures, Fair Value Disclosure	70,895	65,903
Interest Rate Swaps, Fair Value Disclosure	16,832	8,906
Total financial liabilities	3,203,502	3,141,532
Significant Unobservable Inputs (Level 3) [Member]
Financial assets
Loans Receivable, net of ALLL, Fair Value Disclosure	186,201	239,831
Total financial assets	186,201	239,831
Financial liabilities
Subordinated debentures, Fair Value Disclosure	0	0
Total financial liabilities	$ 0	$ 0