Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets
Cash and due from banks	$ 143,041	$ 141,663
Federal funds sold	562	672
Interest bearing deposits in banks	466,928	392,492
Total cash and cash equivalents	610,531	534,827
Investment securities:
Available-for-sale	1,893,652	1,947,706
Held-to-maturity (estimated fair values of $205,443 and $205,926 at March 31, 2014 and December 31, 2013, respectively)	201,436	203,837
Total investment securities	2,095,088	2,151,543
Loans held for investment	4,326,367	4,303,992
Mortgage loans held for sale	38,471	40,861
Total loans	4,364,838	4,344,853
Less allowance for loan losses	81,371	85,339
Net loans	4,283,467	4,259,514
Premises and equipment, net of accumulated depreciation	179,942	179,690
Goodwill	183,673	183,673
Company-owned life insurance	138,027	122,175
Other real estate owned (OREO)	16,594	15,504
Accrued interest receivable	27,135	26,450
Mortgage servicing rights, net of accumulated amortization and impairment reserve	13,474	13,546
Deferred tax asset, net	3,895	12,154
Core deposit intangibles, net of accumulated amortization	4,165	4,519
Other assets	61,834	61,056
Total assets	7,617,825	7,564,651
Deposits:
Non-interest bearing	1,458,460	1,491,683
Interest bearing	4,676,677	4,642,067
Total deposits	6,135,137	6,133,750
Securities sold under repurchase agreements	488,898	457,437
Accounts payable and accrued expenses	43,808	47,523
Accrued interest payable	4,953	4,963
Long-term debt	36,905	36,917
Other borrowed funds	9	3
Subordinated debentures held by subsidiary trusts	82,477	82,477
Total liabilities	6,792,187	6,763,070
Stockholders' equity:
Nonvoting noncumulative preferred stock without par value; authorized 100,000 shares; no shares issued and outstanding as of March 31, 2014 or December 31, 2013	0	0
Common stock	286,553	285,535
Retained earnings	546,444	532,087
Accumulated other comprehensive income, net	(7,359)	(16,041)
Total stockholders' equity	825,638	801,581
Total liabilities and stockholders' equity	$ 7,617,825	$ 7,564,651