CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Operating activities
Net income	$ 36,418	$ 66,924	$ 47,150
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses		6,038	834
Depreciation and amortization		10,208	6,354
Stock-based compensation expense		3,446	2,966
Pension expense (income)	338	182	(637)
Net amortization (accretion) on investment securities		5,178	4,998
Net (gains) losses on sales of investment securities		30	(1,354)
Originations of loans held for sale		(54,041)	(75,543)
Net gains from sales of loans held for sale	(2,316)	(2,904)	(2,543)
Proceeds from sales of loans held for sale		50,004	78,771
Deferred income taxes		(12,104)	3,987
Decrease (increase) cash surrender value of life insurance		(398)	116
Decrease (increase) in interest receivable		(565)	(1,397)
Decrease (increase) in indemnification asset		(1,900)	(2,418)
(Decrease) increase in interest payable		2,596	148
Decrease (increase) in other assets		26,646	(18,472)
(Decrease) increase in other liabilities		10,724	(5,571)
Net cash provided by (used in) operating activities		114,660	41,993
Investing activities
Proceeds from sales of securities available-for-sale		216,197	125,606
Proceeds from calls, paydowns and maturities of securities available-for-sale		161,733	102,893
Purchases of securities available-for-sale		(444,686)	(464,543)
Proceeds from calls, paydowns and maturities of securities held-to-maturity		26,834	72,078
Payments to Acquire Held-to-maturity Securities		14,014	14,441
Net decrease (increase) in interest-bearing deposits with other banks		(3,941)	52,611
Net decrease (increase) in loans and leases		(83,617)	(121,944)
Proceeds from disposal of other real estate owned	618	2,840	2,292
Purchases of premises and equipment		(13,662)	(4,247)
Net cash (paid) acquired from business combinations		64,887	0
Net cash paid for branch divestitures		(41,197)
Net cash provided by (used in) investing activities		(128,626)	(249,695)
Financing activities
Net (decrease) increase in total deposits		(55,757)	(56,879)
Net (decrease) increase in short-term borrowings		178,143	280,421
Payments of long-term debt		51,985	0
Proceeds from FHLB borrowings		50,000	0
Cash dividends paid on common stock		(40,685)	(20,243)
Proceeds from exercise of stock options		267	283
Net cash provided by (used in) financing activities		79,983	203,582
Cash and due from banks:
Change in cash and due from banks		66,017	(4,120)
Cash and due from banks at beginning of period		150,650	121,598	$ 121,598
Cash and due from banks at end of period	216,667	216,667	117,478	150,650
Supplemental schedule for investing activities
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets, Net Of Purchase Consideration	3,328,802	3,328,802		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ 4,007,743	4,007,743		0
Goodwill		$ 678,941	$ 0	$ 0