Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 58,224	$ 44,546	$ 37,356
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Provision for loan losses	40,750	58,151	66,900
Net loss (gain) on disposal of property and equipment	(424)	28	672
Depreciation and amortization	17,112	17,368	20,136
Net premium amortization on investment securities	11,700	10,353	6,762
Net gain on investment securities transactions	(348)	(1,544)	(170)
Net gain on sales of mortgage loans held for sale	(29,606)	(14,443)	(15,321)
Net gain on sales of student loan portfolio	0	0	(374)
Net (gain) loss on sale of mortgage servicing rights	(19)	0	1,525
Net gain on sale of OREO	(1,041)	(552)	(708)
Write-down of OREO	6,724	7,464	6,724
Loss on early extinguishment of debt	428	0	306
Mortgage servicing rights impairment (recovery)	(771)	1,275	(787)
Deferred income tax expense (benefit)	8,762	2,405	(17,257)
Net increase in cash surrender value of company-owned life insurance policies	(1,849)	(1,824)	(1,682)
Stock-based compensation expense	2,485	2,111	1,764
Tax benefits from stock-based compensation	360	204	239
Excess tax benefits from stock-based compensation	(273)	(124)	(225)
Originations of loans held for sale, net	12,122	4,466	1,121
Changes in operating assets and liabilities:
Decrease in accrued interest receivable	3,105	1,654	3,495
Decrease in other assets	4,089	13,039	8,158
Decrease in accrued interest payable	(1,621)	(5,055)	(4,407)
Increase (decrease) in accounts payable and accrued expenses	5,913	3,579	(4,969)
Net cash provided by operating activities	135,822	143,101	109,258
Purchases of investment securities:
Held-to-maturity	(68,305)	(18,846)	(33,118)
Available-for-sale	(1,246,068)	(1,166,364)	(1,317,938)
Proceeds from maturities, paydowns and calls of investment securities:
Held-to-maturity	12,192	12,682	15,134
Available-for-sale	1,252,266	943,490	833,910
Proceeds from sales of mortgage servicing rights	907	596	2,480
Extensions of credit to customers, net of repayments	(128,919)	90,548	71,762
Proceeds from sale of student loan portfolio	0	0	25,032
Recoveries of loans charged-off	8,116	5,231	2,889
Proceeds from sales of OREO	42,814	15,896	20,336
Capital contribution to equity method investment	(900)	0	0
Capital distribution from unconsolidated subsidiary	1,238	0	0
Capital expenditures, net of proceeds from sales	(14,420)	(9,172)	(7,998)
Net cash used in investing activities	(141,079)	(125,939)	(387,511)
Cash flows from financing activities:
Net increase (decrease) in deposits	413,440	(98,742)	101,657
Net increase (decrease) in repurchase agreements	(10,458)	(103,911)	146,013
Net increase (decrease) in short-term borrowings	25	(4,984)	(432)
Repayments of long-term debt	(40)	(302)	(35,851)
Repayment of junior subordinated debentures held by subsidiary trusts	(41,238)	0	0
Proceeds from issuance of common stock	1,911	385	167,400
Common stock issuance costs	0	0	(13,597)
Excess tax benefits from stock-based compensation	273	124	225
Purchase and retirement of common stock	(263)	(248)	(3,699)
Dividends paid to common stockholders	(26,208)	(19,233)	(17,905)
Dividends paid to preferred stockholders	(3,300)	(3,422)	(3,422)
Net cash provided by (used in) financing activities	334,142	(230,333)	340,389
Net increase (decrease) in cash and cash equivalents	328,885	(213,171)	62,136
Cash and cash equivalents at beginning of year	472,447	685,618	623,482
Cash and cash equivalents at end of year	801,332	472,447	685,618
Supplemental disclosures of cash flow information:
Cash paid during the year for income taxes	17,540	16,640	37,325
Cash paid during the year for interest expense	$ 31,735	$ 47,086	$ 67,514