Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Cash and cash equivalents:
Cash and due from banks	$ 258,357	$ 251,411	$ 234,011
Interest-bearing deposits with banks	460,837	124,895	25,950
Federal funds sold and securities purchased under agreements to resell		32,677	47,348
Total cash and cash equivalents	719,194	408,983	307,309
Investment securities:
Securities held to maturity (fair value of $0, $0 and $500, respectively)			500
Securities available for sale, at fair value	1,813,134	1,517,067	1,551,281
Other investments	49,124	25,604	19,229
Total investment securities	1,862,258	1,542,671	1,571,010
Loans held for sale	87,393	22,925	33,752
Loans:
Loans, net	11,229,892	10,962,037	10,855,344
Other real estate owned	13,415	11,410	12,119
Premises and equipment, net	323,506	241,076	241,909
Bank owned life insurance	233,206	230,105	229,075
Deferred tax assets	27,844	37,128	47,943
Mortgage servicing rights	28,674	34,727	36,056
Core deposit and other intangibles	53,083	62,900	66,437
Goodwill	1,002,900	1,002,900	1,002,900
Other assets	170,717	119,466	118,361
Total assets	15,752,082	14,676,328	14,522,215
Deposits:
Noninterest-bearing	3,307,532	3,061,769	3,157,478
Interest-bearing	8,716,255	8,585,164	8,456,397
Total deposits	12,023,787	11,646,933	11,613,875
Federal funds purchased and securities sold under agreements to repurchase	269,072	270,649	279,698
Other borrowings	815,771	266,084	115,919
Other liabilities	292,496	126,366	144,584
Total liabilities	13,401,126	12,310,032	12,154,076
Shareholders' equity:
Common stock - $2.50 par value; authorized 80,000,000 shares; 33,902,726, 35,829,549 and 36,723,238 shares issued and outstanding, respectively	84,757	89,574	91,808
Surplus	1,617,004	1,750,495	1,805,685
Retained earnings	646,325	551,108	515,155
Accumulated other comprehensive income (loss)	2,870	(24,881)	(44,509)
Total shareholders' equity	2,350,956	2,366,296	2,368,139
Total liabilities and shareholders' equity	15,752,082	14,676,328	14,522,215
Acquired credit impaired loans
Loans:
Loans, net	390,714	485,119	512,633
Total loans	396,032	489,723	516,601
Acquired non-credit impaired loans
Loans:
Total loans	1,965,603	2,594,826	2,786,102
Non-acquired loans
Loans:
Total loans	8,928,512	7,933,286	7,606,478
Less allowance for non-acquired loan losses	(54,937)	(51,194)	(49,869)
Loans, net	$ 8,873,575	$ 7,882,092	$ 7,556,609