Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Cash and cash equivalents:
Cash and due from banks	$ 225,259	$ 201,966	$ 182,875
Interest-bearing deposits with banks	185,472	36,241	8,055
Federal funds sold and securities purchased under agreements to resell	21,159	136,241	290,982
Total cash and cash equivalents	431,890	374,448	481,912
Investment securities:
Securities held to maturity (fair value of $4,248, $6,250 and $8,231, respectively)	4,166	6,094	7,921
Securities available for sale, at fair value	1,341,652	999,405	989,610
Other investments	13,076	9,482	9,529
Total investment securities	1,358,894	1,014,981	1,007,060
Loans held for sale	65,995	50,572	48,926
Loans:
Loans, net	8,140,706	6,643,326	6,380,657
Other real estate owned (covered of $0, $0 and $4,222, respectively; non-covered of $20,007, $18,316 and $21,731, respectively)	14,430	18,316	22,427
Premises and equipment, net	201,539	183,510	177,950
Bank owned life insurance	150,476	104,148	102,815
Deferred tax assets	39,921	31,123	25,915
Mortgage servicing rights	29,930	29,037	22,350
Core deposit and other intangibles	52,966	39,848	43,629
Goodwill	595,817	338,340	338,340
Other assets	71,877	72,943	72,012
Total assets	11,154,441	8,900,592	8,723,993
Deposits:
Noninterest-bearing	2,635,147	2,199,046	2,117,246
Interest-bearing	6,396,507	5,135,377	5,046,680
Total deposits	9,031,654	7,334,423	7,163,926
Federal funds purchased and securities sold under agreements to repurchase	334,018	313,773	341,064
Other borrowings	98,147	55,358	55,254
Other liabilities	85,137	62,450	59,406
Total liabilities	9,548,956	7,766,004	7,619,650
Shareholders' equity:
Preferred stock - $.01 par value; authorized 10,000,000 shares; no shares issued and outstanding
Common stock - $2.50 par value; authorized 40,000,000 shares; 29,259,264, 24,230,392 and 24,195,226 shares issued and outstanding, respectively	73,148	60,576	60,488
Surplus	1,134,328	711,307	703,445
Retained earnings	401,706	370,916	333,900
Accumulated other comprehensive income (loss)	(3,697)	(8,211)	6,510
Total shareholders' equity	1,605,485	1,134,588	1,104,343
Total liabilities and shareholders' equity	11,154,441	8,900,592	8,723,993
Acquired credit impaired loans
Loans:
Loans, net	602,481	602,546	658,835
Total loans	606,222		662,587
Non-acquired loans
Loans:
Total loans	5,992,393	5,241,041	4,816,875
Less allowance for non-acquired loan losses	(40,149)	(36,960)	(36,939)
Loans, net	5,952,244	5,204,081	4,779,936
Acquired non-credit impaired loans
Loans:
Loans, net	1,585,981	$ 836,699	941,886
Total loans	$ 1,585,981		$ 941,886