Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest income
Loans and leases	$ 876,472	$ 874,892	$ 700,525
Investment securities:
U. S. Treasury	11,837	15,353	11,656
Government agency	2,883	6,843	7,410
Residential mortgage-backed securities	79,336	65,815	36,492
Corporate bonds	1,783	0	255
State, county and municipal	1	33	13
Other	911	206	385
Total investment securities interest and dividend income	96,751	88,250	56,211
Overnight investments	14,534	6,067	3,712
Total interest income	987,757	969,209	760,448
Interest expense
Deposits	18,169	21,230	24,786
Short-term borrowings	1,965	4,660	9,177
Long-term obligations	22,948	18,414	16,388
Total interest expense	43,082	44,304	50,351
Net interest income (loss)	944,675	924,905	710,097
Provision for loan and lease losses	32,941	20,664	640
Net interest income after provision for loan and lease losses	911,734	904,241	709,457
Noninterest income
Gain on acquisitions	5,831	42,930	0
Cardholder services	83,417	77,342	59,607
Merchant services	95,774	84,207	64,075
Service charges on deposit accounts	89,359	90,546	69,100
Wealth management services	80,221	82,865	66,115
Fees from processing services	71	180	17,989
Securities gains (losses)	26,673	10,817	29,096
Other service charges and fees	26,940	23,807	17,760
Mortgage income	20,348	18,168	5,828
Insurance commissions	11,150	11,757	11,129
ATM income	7,283	7,119	5,388
Adjustments to FDIC receivable	(9,725)	(19,009)	(32,151)
Net impact from FDIC shared-loss termination	16,559	0	0
Other	34,170	36,359	29,277
Total noninterest income	488,071	467,088	343,213
Noninterest expense
Salaries and wages	428,351	429,742	349,279
Employee benefits	104,518	113,309	79,898
Occupancy expense	102,609	98,191	86,775
Equipment expense	92,501	92,639	79,084
Merchant processing	65,440	58,231	42,661
Cardholder processing	24,474	21,735	15,133
FDIC insurance expense	20,967	18,340	12,979
Foreclosure-related expenses	4,490	2,662	17,368
Merger-related expenses	5,341	14,174	13,064
Other	200,047	189,892	152,835
Total noninterest expense	1,048,738	1,038,915	849,076
Income before income taxes	351,067	332,414	203,594
Income taxes	125,585	122,028	65,032
Income taxes	92,439	121,478	98,371
Net income	$ 225,482	$ 210,386	$ 138,562
Average shares outstanding (in shares)	12,010,405	12,010,405	10,221,721
Cash dividends (in dollars per share)	$ 1.20	$ 1.20	$ 1.20
Net income per share	$ 18.77	$ 17.52	$ 13.56