Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Cash and cash equivalents:
Cash and due from banks	$ 250,106	$ 255,775	$ 225,259
Interest-bearing deposits with banks	73,013	117,635	185,472
Federal funds sold and securities purchased under agreements to resell	73,730	4,217	21,159
Total cash and cash equivalents	396,849	377,627	431,890
Investment securities:
Securities held to maturity (fair value of $503, $2,556 and $4,248, respectively)	499	2,529	4,166
Securities available for sale, at fair value	1,577,999	1,648,193	1,340,427
Other investments	19,229	23,047	14,301
Total investment securities	1,597,727	1,673,769	1,358,894
Loans held for sale	36,968	70,890	65,995
Loans:
Loans, net	10,778,068	10,575,417	8,140,706
Other real estate owned	17,222	11,203	14,430
Premises and equipment, net	245,288	255,565	201,539
Bank owned life insurance	227,588	225,132	150,476
Deferred tax assets	48,853	45,902	39,921
Mortgage servicing rights	35,107	31,119	29,930
Core deposit and other intangibles	69,975	73,789	52,966
Goodwill	1,002,722	999,586	595,817
Other assets	110,121	126,590	71,877
Total assets	14,566,488	14,466,589	11,154,441
Deposits:
Noninterest-bearing	3,152,828	3,047,432	2,635,147
Interest-bearing	8,485,461	8,485,334	6,396,507
Total deposits	11,638,289	11,532,766	9,031,654
Federal funds purchased and securities sold under agreements to repurchase	331,969	286,857	334,018
Other borrowings	115,754	216,385	98,147
Other liabilities	132,109	121,661	85,137
Total liabilities	12,218,121	12,157,669	9,548,956
Shareholders' equity:
Common stock - $2.50 par value; authorized 80,000,000, 80,000,000 and 40,000,000 shares, respectively; 36,825,556, 36,759,656 and 29,259,264 shares issued and outstanding, respectively	92,064	91,899	73,148
Surplus	1,811,446	1,807,601	1,134,328
Retained earnings	480,928	419,847	401,706
Accumulated other comprehensive loss	(36,071)	(10,427)	(3,697)
Total shareholders' equity	2,348,367	2,308,920	1,605,485
Total liabilities and shareholders' equity	14,566,488	14,466,589	11,154,441
Acquired credit impaired loans
Loans:
Loans, net	551,979	618,803	602,481
Total loans	556,405	623,430	606,222
Acquired non-credit impaired loans
Loans:
Loans, net	3,076,424	3,507,907	1,585,981
Total loans	3,076,424	3,507,907	1,585,981
Non-acquired loans
Loans:
Total loans	7,197,539	6,492,155	5,992,393
Less allowance for non-acquired loan losses	(47,874)	(43,448)	(40,149)
Loans, net	$ 7,149,665	$ 6,448,707	$ 5,952,244