Condensed Consolidated Statements of Earnings - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income:
Loans and leases	$ 260,300	$ 251,085	$ 234,618	$ 511,385	$ 458,796
Investment securities	27,730	26,138	24,689	53,868	47,728
Deposits in financial institutions	484	552	237	1,036	429
Total interest income	288,514	277,775	259,544	566,289	506,953
Interest expense:
Deposits	16,367	13,818	10,205	30,185	18,582
Borrowings	2,649	920	1,066	3,569	2,084
Subordinated debentures	7,166	6,537	5,800	13,703	11,362
Total interest expense	26,182	21,275	17,071	47,457	32,028
Net interest income	262,332	256,500	242,473	518,832	474,925
Provision for credit losses	17,500	4,000	11,499	21,500	36,227
Net interest income after provision for credit losses	244,832	252,500	230,974	497,332	438,698
Noninterest income:
Service charges on deposit accounts	4,265	4,174	3,510	8,439	7,268
Other commissions and fees	11,767	10,265	10,583	22,032	20,973
Leased equipment income	9,790	9,587	11,635	19,377	21,110
Gain on sale of loans and leases	106	4,569	649	4,675	1,361
Gain on sale of securities	253	6,311	1,651	6,564	1,552
Other income	13,457	3,653	7,254	17,110	18,132
Total noninterest income	39,638	38,559	35,282	78,197	70,396
Noninterest expense:
Compensation	69,913	71,023	65,288	140,936	130,168
Occupancy	13,575	13,223	11,811	26,798	23,419
Data processing	6,896	6,659	6,337	13,555	13,352
Other professional services	5,257	4,439	3,976	9,696	7,354
Insurance and assessments	5,330	5,727	4,856	11,057	9,647
Intangible asset amortization	5,587	6,346	3,065	11,933	6,129
Leased equipment depreciation	5,237	5,375	5,232	10,612	10,857
Foreclosed assets income, net	(61)	(122)	(157)	(183)	(14)
Acquisition, integration and reorganization costs	0	0	1,700	0	2,200
Loan expense	3,058	2,271	3,884	5,329	7,271
Other expense	11,657	12,454	11,715	24,111	23,868
Total noninterest expense	126,449	127,395	117,707	253,844	234,251
Earnings before income taxes	158,021	163,664	148,549	321,685	274,843
Income tax expense	(42,286)	(45,388)	(54,902)	(87,674)	(102,528)
Net earnings	$ 115,735	$ 118,276	$ 93,647	$ 234,011	$ 172,315
Earnings per share:
Net earnings (usd per share)	$ 0.92	$ 0.93	$ 0.77	$ 1.85	$ 1.42
Net earnings (usd per share)	0.92	0.93	0.77	1.85	1.42
Dividends declared per share (usd per share)	$ 0.60	$ 0.50	$ 0.50	$ 1.10	$ 1