Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income
Loans and leases	$ 261,086	$ 235,732	$ 513,068	$ 462,362
Investment securities:
Total investment securities interest and dividend income	37,179	30,406	72,199	60,157
Overnight investments	5,612	6,404	11,211	10,880
Total interest income	303,877	272,542	596,478	533,399
Interest expense
Deposits	4,521	4,132	8,277	8,568
Short-term borrowings	821	1,176	2,255	1,756
Long-term obligations	2,316	5,625	5,290	11,123
Total interest expense	7,658	10,933	15,822	21,447
Net interest income	296,219	261,609	580,656	511,952
Provision (credit) for loan and lease losses	8,438	12,324	16,043	20,555
Net interest income after provision for loan and lease losses	287,781	249,285	564,613	491,397
Noninterest income
Gain on acquisitions	0	122,728	0	134,745
Revenue from contract with customers	90,486	84,770	179,221	166,981
Securities gains (losses), net	0	3,351	0	3,327
Marketable equity securities gain (loss), net	4,440	0	5,411	0
Net Impact from FDIC shared-loss termination	0	0	0	(45)
Gain (Loss) on Extinguishment of Debt	0	0	25,814	0
Other	6,001	6,792	13,165	12,279
Total noninterest income	100,927	217,641	223,611	317,287
Noninterest expense
Salaries and wages	129,841	121,826	259,044	238,188
Employee benefits	29,715	25,383	61,806	52,560
Occupancy expense	26,100	26,059	54,054	50,821
Equipment expense	25,167	24,654	50,141	49,242
Merchant processing				20,800
Cardholder processing				6,800
FDIC insurance expense	5,492	5,705	11,225	11,298
Foreclosure-related expenses	3,974	2,376	8,120	6,139
Merger-related expenses	2,412	6,853	3,010	7,686
Other	43,292	42,191	86,656	75,812
Total noninterest expense	265,993	255,047	534,056	491,746
Income before income taxes	122,715	211,879	254,168	316,938
Income taxes	29,424	77,219	60,646	114,657
Net income	$ 93,291	$ 134,660	$ 193,522	$ 202,281
Average shares outstanding (in shares)	12,010,405	12,010,405	12,010,405	12,010,405
Net income per share	$ 7.77	$ 11.21	$ 16.11	$ 16.84
Cardholder services, net
Noninterest income
Revenue from contract with customers	$ 14,925	$ 14,518	$ 29,707	$ 27,361
Merchant services, net
Noninterest income
Revenue from contract with customers	6,478	5,800	12,655	11,556
Service charges on deposit accounts
Noninterest income
Revenue from contract with customers	25,952	25,862	52,495	48,004
Wealth management services
Noninterest income
Revenue from contract with customers	25,515	21,920	49,084	42,882
Other service charges and fees
Noninterest income
Revenue from contract with customers	7,756	6,628	15,236	14,229
Mortgage income
Noninterest income
Revenue from contract with customers	4,703	4,966	8,940	12,542
Insurance commissions
Noninterest income
Revenue from contract with customers	2,940	2,563	6,716	6,121
ATM income
Noninterest income
Revenue from contract with customers	$ 2,217	$ 2,513	$ 4,388	$ 4,286