Consolidated Balance Sheets - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 253,860	$ 386,948
Interest-bearing bank deposits	61,288	92,157
Federal funds sold	253	227
Securities available for sale, at fair value (amortized cost of $3,008,951 and $2,949,057)	2,915,648	2,910,869
Securities held to maturity (fair value of $2,952,295 and $2,962,010)	3,014,428	2,977,511
Loans held for sale	21,827	39,865
Loans	19,092,504	19,004,163
Less: allowance for loan losses	(210,713)	(217,308)
Loans, net	18,881,791	18,786,855
Property and equipment, net of accumulated depreciation of $218,540 and $214,998	334,254	333,663
Prepaid expense	29,669	28,015
Other real estate, net	13,963	14,862
Accrued interest receivable	80,812	82,191
Goodwill	745,523	745,523
Other intangible assets, net	85,021	90,640
Life insurance contracts	544,427	541,081
Deferred tax asset, net	52,735	53,979
Other assets	261,838	251,700
Total assets	27,297,337	27,336,086
Deposits
Noninterest-bearing	8,230,060	8,307,497
Interest-bearing	14,255,662	13,945,705
Total deposits	22,485,722	22,253,202
Short-term borrowings	1,452,097	1,703,890
Long-term debt	300,443	305,513
Accrued interest payable	11,801	8,680
Other liabilities	151,236	179,852
Total liabilities	24,401,299	24,451,137
Stockholders' equity:
Common Stock	292,716	292,716
Capital surplus	1,723,689	1,718,117
Retained earnings	1,060,182	1,008,518
Accumulated other comprehensive loss, net	(180,549)	(134,402)
Total stockholders' equity	2,896,038	2,884,949
Total liabilities and stockholders' equity	$ 27,297,337	$ 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	85,285	85,200