Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Cash and cash equivalents:
Cash and due from banks	$ 225,865	$ 251,411	$ 227,264
Interest-bearing deposits with banks	723,726	124,895	362,773
Federal funds sold and securities purchased under agreements to resell		32,677	54,467
Total cash and cash equivalents	949,591	408,983	644,504
Investment securities:
Securities held to maturity (fair value of $0 and $1,284, respectively)			1,274
Securities available for sale, at fair value	1,466,249	1,517,067	1,640,837
Other investments	40,624	25,604	23,479
Total investment securities	1,506,873	1,542,671	1,665,590
Loans held for sale	33,297	22,925	42,690
Loans:
Loans, net	11,089,600	10,962,037	10,589,521
Other real estate owned	11,297	11,410	11,073
Premises and equipment, net	322,553	241,076	253,605
Bank owned life insurance	230,629	230,105	226,222
Deferred tax assets	31,884	37,128	46,736
Mortgage servicing rights	32,415	34,727	34,196
Core deposit and other intangibles	59,619	62,900	70,376
Goodwill	1,002,900	1,002,900	999,592
Other assets	136,229	119,466	105,004
Total assets	15,406,887	14,676,328	14,689,109
Deposits:
Noninterest-bearing	3,219,864	3,061,769	3,120,818
Interest-bearing	8,699,107	8,585,164	8,542,280
Total deposits	11,918,971	11,646,933	11,663,098
Federal funds purchased and securities sold under agreements to repurchase	276,891	270,649	357,574
Other borrowings	616,250	266,084	215,589
Other liabilities	218,298	126,366	130,269
Total liabilities	13,030,410	12,310,032	12,366,530
Shareholders' equity:
Common stock - $2.50 par value; authorized 80,000,000 shares; 35,368,521, 35,829,549 and 36,783,438 shares issued and outstanding, respectively	88,421	89,574	91,958
Surplus	1,719,396	1,750,495	1,807,989
Retained earnings	582,034	551,108	452,982
Accumulated other comprehensive loss	(13,374)	(24,881)	(30,350)
Total shareholders' equity	2,376,477	2,366,296	2,322,579
Total liabilities and shareholders' equity	15,406,887	14,676,328	14,689,109
Acquired credit impaired loans
Loans:
Loans, net	452,258	485,119	597,274
Total loans	456,772	489,723	601,358
Acquired non-credit impaired loans
Loans:
Total loans	2,378,737	2,594,826	3,274,938
Non-acquired loans
Loans:
Total loans	8,310,613	7,933,286	6,762,512
Less allowance for non-acquired loan losses	(52,008)	(51,194)	(45,203)
Loans, net	$ 8,258,605	$ 7,882,092	$ 6,717,309