Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets
Cash and due from banks	$ 128,452	$ 177,978
Federal funds sold	786	730
Interest bearing deposits in banks	238,979	622,624
Total cash and cash equivalents	368,217	801,332
Investment securities:
Available-for-sale	1,923,216	1,995,258
Held-to-maturity (estimated fair values of $199,078 and $161,877 at September 30, 2012 and December 31, 2011, respectively)	215,323	208,223
Total investment securities	2,138,539	2,203,481
Loans held for investment	4,223,078	4,157,470
Mortgage loans held for sale	74,286	66,442
Total loans	4,297,364	4,223,912
Less allowance for loan losses	98,528	100,511
Net loans	4,198,836	4,123,401
Premises and equipment, net of accumulated depreciation	181,940	187,565
Goodwill	183,673	183,673
Company-owned life insurance	77,602	76,729
Other real estate owned (OREO)	22,782	32,571
Accrued interest receivable	29,272	28,869
Mortgage servicing rights, net of accumulated amortization and impairment reserve	13,304	12,653
Deferred tax asset, net	15,397	2,597
Core deposit intangibles, net of accumulated amortization	5,228	5,937
Other assets	56,718	62,953
Total assets	7,291,508	7,721,761
Deposits:
Non-interest bearing	1,393,732	1,495,309
Interest bearing	4,536,600	4,745,102
Total deposits	5,930,332	6,240,411
Securities sold under repurchase agreements	421,314	505,785
Accounts payable and accrued expenses	44,054	48,208
Accrued interest payable	6,236	6,502
Long-term debt	37,139	37,160
Other borrowed funds	2	32
Preferred stock pending redemption	0	50,000
Subordinated debentures held by subsidiary trusts	82,477	82,477
Total liabilities	6,521,554	6,970,575
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	0	0
Common stock	279,232	271,335
Retained earnings	499,761	463,860
Accumulated other comprehensive income, net	(9,039)	15,991
Total stockholders' equity	769,954	751,186
Total liabilities and stockholders' equity	$ 7,291,508	$ 7,721,761