Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets
Cash and due from banks	$ 128,341	$ 142,502
Federal funds sold	304	309
Interest bearing deposits in banks	494,279	329,636
Total cash and cash equivalents	622,924	472,447
Investment securities:
Available-for-sale	1,955,436	2,016,864
Held-to-maturity (estimated fair values of $166,932 and $161,877 at March 31, 2012 and December 31, 2011, respectively)	158,070	152,781
Total investment securities	2,113,506	2,169,645
Loans held for investment	4,099,936	4,133,028
Mortgage loans held for sale	58,680	53,521
Total loans	4,158,616	4,186,549
Less allowance for loan losses	115,902	112,581
Net loans	4,042,714	4,073,968
Premises and equipment, net of accumulated depreciation	185,230	184,771
Goodwill	183,673	183,673
Company-owned life insurance	75,342	74,880
Other real estate owned (OREO)	44,756	37,452
Accrued interest receivable	30,407	31,974
Mortgage servicing rights, net of accumulated amortization and impairment reserve	11,833	11,555
Deferred tax asset, net	9,571	9,628
Core deposit intangibles, net of accumulated amortization	7,002	7,357
Other assets	67,348	68,177
Total assets	7,394,306	7,325,527
Deposits:
Non-interest bearing	1,284,823	1,271,709
Interest bearing	4,626,011	4,555,262
Total deposits	5,910,834	5,826,971
Securities sold under repurchase agreements	491,058	516,243
Accounts payable and accrued expenses	43,972	42,248
Accrued interest payable	8,255	8,123
Long-term debt	37,191	37,200
Other borrowed funds	6	7
Subordinated debentures held by subsidiary trusts	123,715	123,715
Total liabilities	6,615,031	6,554,507
Stockholders' equity:
Nonvoting noncumulative preferred stock without par value; authorized 100,000 shares; issued and outstanding 5,000 shares as of March 31, 2012 and December 31, 2011	50,000	50,000
Common stock	268,411	266,842
Retained earnings	441,370	435,144
Accumulated other comprehensive income, net	19,494	19,034
Total stockholders' equity	779,275	771,020
Total liabilities and stockholders' equity	$ 7,394,306	$ 7,325,527