Carrying Amount and Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Carrying Amount
Financial Assets
Cash and Cash Equivalents	$ 155,657	$ 187,040
Investment securities, available-for-sale	3,222,829	3,683,005
Loans Held-for-sale	46,738	145,501
Loans Receivable, net of ALLL	3,932,487	3,266,571
Accrued interest receivable	41,898	37,770
Non-marketable Equity Securities	52,192	48,812
Interest rate swaps	1,896
Total Financial Assets	7,453,697	7,368,699
Financial Liabilities
Deposits	5,579,967	5,364,461
FHLB advances	840,182	997,013
Repurchase agreements and other borrowed funds	321,781	299,540
Subordinated debentures	125,562	125,418
Accrued interest payable	3,505	4,675
Interest rate swaps		16,832
Total financial liabilities	6,870,997	6,807,939
Estimated Fair Value | Level 1
Financial Assets
Cash and Cash Equivalents	155,657	187,040
Investment securities, available-for-sale	0	0
Loans Held-for-sale	46,738	145,501
Loans Receivable, net of ALLL	0	0
Accrued interest receivable	41,898	37,770
Non-marketable Equity Securities	0	0
Interest rate swaps	0
Total Financial Assets	244,293	370,311
Financial Liabilities
Deposits	4,258,213	3,585,126
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Accrued interest payable	3,505	4,675
Interest rate swaps		0
Total financial liabilities	4,261,718	3,589,801
Estimated Fair Value | Level 2
Financial Assets
Cash and Cash Equivalents	0	0
Investment securities, available-for-sale	3,222,829	3,683,005
Loans Held-for-sale	0	0
Loans Receivable, net of ALLL	3,807,993	3,184,987
Accrued interest receivable	0	0
Non-marketable Equity Securities	52,192	48,812
Interest rate swaps	1,896
Total Financial Assets	7,084,910	6,916,804
Financial Liabilities
Deposits	1,341,382	1,789,134
FHLB advances	857,551	1,027,101
Repurchase agreements and other borrowed funds	321,781	299,540
Subordinated debentures	71,501	70,895
Accrued interest payable	0	0
Interest rate swaps		16,832
Total financial liabilities	2,592,215	3,203,502
Estimated Fair Value | Level 3
Financial Assets
Cash and Cash Equivalents	0	0
Investment securities, available-for-sale	0	0
Loans Held-for-sale	0	0
Loans Receivable, net of ALLL	187,731	186,201
Accrued interest receivable	0	0
Non-marketable Equity Securities	0	0
Interest rate swaps	0
Total Financial Assets	187,731	186,201
Financial Liabilities
Deposits	0	0
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Accrued interest payable	0	0
Interest rate swaps		0
Total financial liabilities	$ 0	$ 0