Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Cash and cash equivalents:
Cash and due from banks	$ 251,631	$ 251,411	$ 250,106
Interest-bearing deposits with banks	500,340	124,895	73,013
Federal funds sold and securities purchased under agreements to resell	100,000	32,677	73,730
Total cash and cash equivalents	851,971	408,983	396,849
Investment securities:
Securities held to maturity (fair value of $0, $0 and $503, respectively)			499
Securities available for sale, at fair value	1,717,276	1,517,067	1,577,999
Other investments	49,124	25,604	19,229
Total investment securities	1,766,400	1,542,671	1,597,727
Loans held for sale	47,796	22,925	36,968
Loans:
Loans, net	11,167,979	10,962,037	10,778,068
Other real estate owned	14,506	11,410	17,222
Premises and equipment, net	321,348	241,076	245,288
Bank owned life insurance	231,708	230,105	227,588
Deferred tax assets	28,240	37,128	48,853
Mortgage servicing rights	30,332	34,727	35,107
Core deposit and other intangibles	56,351	62,900	69,975
Goodwill	1,002,900	1,002,900	1,002,722
Other assets	163,806	119,466	110,121
Total assets	15,683,337	14,676,328	14,566,488
Deposits:
Noninterest-bearing	3,255,906	3,061,769	3,152,828
Interest-bearing	8,666,374	8,585,164	8,485,461
Total deposits	11,922,280	11,646,933	11,638,289
Federal funds purchased and securities sold under agreements to repurchase	298,029	270,649	331,969
Other borrowings	816,414	266,084	115,754
Other liabilities	272,636	126,366	132,109
Total liabilities	13,309,359	12,310,032	12,218,121
Shareholders' equity:
Common stock - $2.50 par value; authorized 80,000,000 shares; 34,735,587, 35,829,549 and 36,825,556 shares issued and outstanding, respectively	86,839	89,574	92,064
Surplus	1,676,229	1,750,495	1,811,446
Retained earnings	609,444	551,108	480,928
Accumulated other comprehensive income (loss)	1,466	(24,881)	(36,071)
Total shareholders' equity	2,373,978	2,366,296	2,348,367
Total liabilities and shareholders' equity	15,683,337	14,676,328	14,566,488
Acquired credit impaired loans
Loans:
Loans, net	419,961	485,119	551,979
Total loans	424,584	489,723	556,405
Acquired non-credit impaired loans
Loans:
Total loans	2,180,281	2,594,826	3,076,424
Non-acquired loans
Loans:
Total loans	8,621,327	7,933,286	7,197,539
Less allowance for non-acquired loan losses	(53,590)	(51,194)	(47,874)
Loans, net	$ 8,567,737	$ 7,882,092	$ 7,149,665