CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net income	$ 98,203	$ 66,021
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(251)	45,677
Depreciation and amortization	16,281	14,790
Stock-based compensation expense	5,335	3,733
Pension expense (income)	1,695	926
Net amortization (accretion) on investment securities	18,989	8,372
Net (gain) loss on sales of investment securities	431	57
Originations of loans held for sale	(423,914)	(385,371)
Net gains from sales of loans held for sale	(17,943)	(19,493)
Proceeds from sales of loans held for sale	447,255	374,594
Deferred income taxes	5,863	(9,752)
Amortization of operating leases	3,701	4,001
Payments for operating leases	(3,437)	(3,873)
Decrease (increase) cash surrender value of life insurance	647	1,098
Decrease (increase) in interest receivable	2,102	(11,611)
(Decrease) increase in interest payable	(1,720)	(3,240)
Decrease (increase) in other assets	93,861	(330,020)
(Decrease) increase in other liabilities	(39,569)	180,120
Net cash provided by (used in) operating activities	205,962	(66,219)
Investing activities
Proceeds from sales of securities available-for-sale	212,246	41,303
Proceeds from calls, paydowns and maturities of securities available-for-sale	550,239	401,771
Purchases of securities available-for-sale	(1,394,143)	(456,917)
Proceeds from calls, paydowns and maturities of securities held-to-maturity	20,371	15,664
Payments to Acquire Other Investments	5,401	18,659
Net decrease (increase) in interest-bearing deposits with other banks	(18,305)	18,103
Net decrease (increase) in loans and leases	378,739	(982,748)
Proceeds from disposal of other real estate owned	1,036	977
Purchases of premises and equipment	(5,163)	(9,758)
Net cash provided by (used in) investing activities	(251,941)	(990,264)
Financing activities
Net (decrease) increase in total deposits	274,177	1,491,186
Net (decrease) increase in short-term borrowings	306,197	(1,161,834)
Payments of long-term debt	463,382	90,133
Proceeds from (Repayments of) Other Long-term Debt	0	811,772
Proceeds from Issuance of Subordinated Long-term Debt	0	150,000
Cash dividends paid on common stock	(44,337)	(44,946)
Treasury stock purchase	50,846	16,686
Proceeds from exercise of stock options	34	72
Net cash provided by (used in) financing activities	21,843	1,139,431
Cash and due from banks:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(24,136)	82,948
Cash and due from banks at beginning of period	231,054	200,691
Cash and due from banks at end of period	206,918	283,639
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Equity Securities, FV-NI, Unrealized Gain (Loss)	(273)	(52)
Payments to Acquire Held-to-maturity Securities	(1,000)	0
Proceeds from Maturities, Prepayments and Calls of Other Investments	9,440	0
Interest Paid, Excluding Capitalized Interest, Operating Activities	18,341	46,247
Income Taxes Paid	$ 10,938	$ 6,297