Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income
Loans and leases	$ 272,215	$ 246,260	$ 785,283	$ 708,622
Investment securities and dividend income	38,770	29,706	110,969	89,863
Overnight investments	4,721	8,367	15,932	19,247
Total interest income	315,706	284,333	912,184	817,732
Interest expense
Deposits	5,147	3,839	13,424	12,407
Short-term borrowings	685	1,429	2,940	3,185
Long-term obligations	2,512	5,890	7,802	17,013
Total interest expense	8,344	11,158	24,166	32,605
Net interest income	307,362	273,175	888,018	785,127
Provision (credit) for loan and lease losses	840	7,946	16,883	28,501
Net interest income after provision for loan and lease losses	306,522	265,229	871,135	756,626
Noninterest income
Gain on acquisitions	0	0	0	134,745
Revenue from contract with customers	87,436	87,538	266,657	254,520
Securities gains (losses), net	0	1,337	0	4,664
Marketable equity securities gain (loss), net	3,854	0	9,265	0
Gain (Loss) on Extinguishment of Debt	703	0	26,517	0
Other	2,538	7,187	15,703	19,421
Total noninterest income	94,531	96,062	318,142	413,350
Noninterest expense
Salaries and wages	133,867	124,888	392,911	363,076
Employee benefits	28,850	25,416	90,656	77,976
Occupancy expense	26,632	26,594	80,686	77,415
Equipment expense	25,880	23,887	76,021	73,129
FDIC insurance expense	5,186	5,449	16,411	16,747
Collection and foreclosure-related expenses	4,269	3,443	12,389	9,582
Merger-related expenses	1,126	562	4,136	8,248
Other	41,727	47,403	128,383	123,216
Total noninterest expense	267,537	257,642	801,593	749,389
Income before income taxes	133,516	103,649	387,684	420,587
Income taxes	16,198	36,585	76,844	151,242
Net income	$ 117,318	$ 67,064	$ 310,840	$ 269,345
Average shares outstanding (in shares)	11,971,460	12,010,405	11,997,281	12,010,405
Net income per share	$ 9.80	$ 5.58	$ 25.91	$ 22.43
Cardholder services, net
Noninterest income
Revenue from contract with customers	$ 14,678	$ 15,487	$ 44,385	$ 42,848
Merchant services, net
Noninterest income
Revenue from contract with customers	5,857	5,528	18,512	17,085
Service charges on deposit accounts
Noninterest income
Revenue from contract with customers	25,994	25,951	78,489	73,955
Wealth management services
Noninterest income
Revenue from contract with customers	24,459	21,234	73,543	64,116
Other service charges and fees
Noninterest income
Revenue from contract with customers	7,651	7,073	22,887	21,302
Mortgage income
Noninterest income
Revenue from contract with customers	4,123	6,775	13,063	19,317
Insurance commissions
Noninterest income
Revenue from contract with customers	2,755	2,894	9,471	9,015
ATM income
Noninterest income
Revenue from contract with customers	$ 1,919	$ 2,596	$ 6,307	$ 6,882