Consolidated Balance Sheets - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 339,609	$ 386,948
Interest-bearing bank deposits	107,635	92,157
Federal funds sold	439	227
Securities available for sale, at fair value (amortized cost of $3,048,851 and $2,949,057)	2,918,185	2,910,869
Securities held to maturity (fair value of $2,975,455 and $2,962,010)	3,069,262	2,977,511
Loans held for sale	29,043	39,865
Loans	19,543,717	19,004,163
Less: allowance for loan losses	(214,550)	(217,308)
Loans, net	19,329,167	18,786,855
Property and equipment, net of accumulated depreciation of $221,295 and $214,998	343,833	333,663
Prepaid expenses	35,470	28,015
Other real estate and foreclosed assets, net	27,475	27,542
Accrued interest receivable	87,567	82,191
Goodwill	791,157	745,523
Other intangible assets, net	101,438	90,640
Life insurance contracts	550,261	541,081
Deferred tax asset, net	59,570	53,979
Other assets	308,064	239,020
Total assets	28,098,175	27,336,086
Deposits
Noninterest-bearing	8,140,530	8,307,497
Interest-bearing	14,277,277	13,945,705
Total deposits	22,417,807	22,253,202
Short-term borrowings	2,276,647	1,703,890
Long-term debt	215,912	305,513
Accrued interest payable	15,986	8,680
Other liabilities	192,945	179,852
Total liabilities	25,119,297	24,451,137
Stockholders' equity:
Common stock	292,716	292,716
Capital surplus	1,735,444	1,718,117
Retained earnings	1,170,897	1,008,518
Accumulated other comprehensive loss, net	(220,179)	(134,402)
Total stockholders' equity	2,978,878	2,884,949
Total liabilities and stockholders' equity	$ 28,098,175	$ 27,336,086
Common shares authorized (par value of 3.33 per share)	350,000	350,000
Common shares issued	87,903	87,903
Common shares outstanding	85,364	85,200