Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 44,546	$ 37,356	$ 53,863
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Provision for loan losses	58,151	66,900	45,300
Net loss on disposal of property and equipment	28	672	306
Depreciation and amortization	17,368	20,136	22,286
Net premium amortization on investment securities	10,353	6,762	1,293
Net gains on investment securities transactions	(1,544)	(170)	(137)
Net gains on sales of mortgage loans held for sale	(14,443)	(15,321)	(18,315)
Net gain on sale of student loan portfolio	0	(374)	0
Net loss on sale of mortgage servicing rights	0	1,525	48
Write-down of OREO	7,464	6,724	5,545
Write-down of equipment pending disposal	0	0	350
Loss on early extinguishment of debt	0	306	0
Mortgage servicing rights impairment (recovery)	1,275	(787)	(7,224)
Deferred income tax expense (benefit)	2,405	(17,257)	5,547
Net increase in cash surrender value of company-owned life insurance policies	(1,824)	(1,682)	(1,859)
Stock-based compensation expense	2,111	1,764	1,067
Tax benefits from stock-based compensation expense	204	239	742
Excess tax benefits from stock-based compensation	(124)	(225)	(719)
Originations of loans held for sale	4,466	1,121	19,280
Changes in operating assets and liabilities:
Decrease in accrued interest receivable	1,654	3,495	1,571
Decrease (increase) in other assets	12,487	7,450	(36,120)
Decrease in accrued interest payable	(5,055)	(4,407)	(2,946)
Increase (decrease) in accounts payable and accrued expenses	3,579	(4,969)	(8,043)
Net cash provided by operating activities	143,101	109,258	81,835
Purchases of investment securities:
Held-to-maturity	(18,846)	(33,118)	(9,910)
Available-for-sale	(1,166,364)	(1,317,938)	(868,917)
Proceeds from maturities, paydowns and calls of investment securities:
Held-to-maturity	12,682	15,134	19,785
Available-for-sale	943,490	833,910	493,389
Proceeds from sales of mortgage servicing rights, net of acquisitions	596	2,480	2,051
Extensions of credit to customers, net of repayments	90,548	71,762	146,943
Proceeds from sale of student loan portfolio	0	25,032	0
Recoveries of loans charged-off	5,231	2,889	2,392
Proceeds from sales of OREO	15,896	20,336	10,849
Capital expenditures, net of sales	(9,172)	(7,998)	(26,393)
Net cash used in investing activities	(125,939)	(387,511)	(229,811)
Cash flows from financing activities:
Net (decrease) increase in deposits	(98,742)	101,657	649,797
Net decrease in federal funds purchased	0	0	(30,625)
Net (decrease) increase in repurchase agreements	(103,911)	146,013	(51,360)
Net decrease in short-term borrowings	(4,984)	(432)	(73,793)
Repayments of long-term debt	(302)	(35,851)	(10,795)
Debt issuance costs	0	0	(261)
Proceeds from issuance of common stock	385	167,400	3,914
Common stock issuance costs	0	(13,597)	0
Excess tax benefits from stock-based compensation	124	225	719
Purchase and retirement of common stock	(248)	(3,699)	(11,052)
Dividends paid to common stockholders	(19,233)	(17,905)	(15,694)
Dividends paid to preferred stockholders	(3,422)	(3,422)	(3,422)
Net cash provided by (used in) financing activities	(230,333)	340,389	457,428
Net increase (decrease) in cash and cash equivalents	(213,171)	62,136	309,452
Cash and cash equivalents at beginning of period	685,618	623,482	314,030
Cash and cash equivalents at end of year	472,447	685,618	623,482
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	16,640	37,325	25,813
Cash paid during the period for interest expense	47,086	67,514	87,844
Retained Earnings [Member]
Cash flows from operating activities:
Net income	$ 44,546	$ 37,356	$ 53,863