Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets
Cash and due from banks	$ 124,275	$ 142,502
Federal funds sold	1,215	309
Interest bearing deposits in banks	485,845	329,636
Total cash and cash equivalents	611,335	472,447
Investment securities:
Available-for-sale	1,979,154	2,016,864
Held-to-maturity (estimated fair values of $199,078 and $161,877 at September 30, 2012 and December 31, 2011, respectively)	187,573	152,781
Total investment securities	2,166,727	2,169,645
Loans held for investment	4,107,171	4,133,028
Mortgage loans held for sale	72,880	53,521
Total loans	4,180,051	4,186,549
Less allowance for loan losses	99,006	112,581
Net loans	4,081,045	4,073,968
Premises and equipment, net of accumulated depreciation	188,851	184,771
Goodwill	183,673	183,673
Company-owned life insurance	76,371	74,880
Other real estate owned (OREO)	39,971	37,452
Accrued interest receivable	33,416	31,974
Mortgage servicing rights, net of accumulated amortization and impairment reserve	12,334	11,555
Deferred tax asset, net	1,638	9,628
Core deposit intangibles, net of accumulated amortization	6,291	7,357
Other assets	59,500	68,177
Total assets	7,461,152	7,325,527
Deposits:
Non-interest bearing	1,443,773	1,271,709
Interest bearing	4,591,959	4,555,262
Total deposits	6,035,732	5,826,971
Securities sold under repurchase agreements	460,805	516,243
Accounts payable and accrued expenses	40,386	42,248
Accrued interest payable	6,706	8,123
Long-term debt	37,170	37,200
Other borrowed funds	6	7
Subordinated debentures held by subsidiary trusts	82,477	123,715
Total liabilities	6,663,282	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	270,553	266,842
Retained earnings	458,506	435,144
Accumulated other comprehensive income, net	18,811	19,034
Total stockholders' equity	797,870	771,020
Total liabilities and stockholders' equity	$ 7,461,152	$ 7,325,527