Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash Flows from Operating Activities
Interest and dividends received	$ 301,634	$ 331,953
Service charges and other fees received	29,918	31,441
Interest paid	(10,975)	(16,155)
Net cash paid to vendors, employees and others	(136,948)	(140,482)
Income taxes	(45,610)	(59,347)
Net cash provided by operating activities	138,019	147,410
Cash Flows from Investing Activities
Net change in interest-earning balances from depository institutions	(41,436)	1,997
Proceeds from sale of investment securities held-for-sale	0	152,644
Proceeds from repayment of investment securities available-for-sale	426,684	268,766
Proceeds from maturity of investment securities available-for-sale	3,506	6,059
Purchases of investment securities available-for-sale	(870,934)	(225,416)
Proceeds from repayment and maturity of investment securities held-to-maturity	106,491	81,001
Purchases of investment securities held-to-maturity	(11,210)	(42,917)
Net increase in equity investments	(2,890)	(3,511)
Net (increase) decrease in loan and lease finance receivables	(815,151)	289,490
Proceeds on eminent domain condemnation, net	0	5,685
Proceeds from sale of building, net of selling costs	2,131	5,487
Purchase of premises and equipment	(2,444)	(3,061)
Proceeds from BOLI death benefit	4,589	1,509
Proceeds from sales of other real estate owned	0	523
Net cash (used in) provided by investing activities	(1,200,664)	538,256
Cash Flows from Financing Activities
Net increase in other deposits	2,465,066	37,061
Net decrease in time deposits	(1,160)	(70,221)
Net increase (decrease) in other borrowings	10,000	(275,086)
Net increase (decrease) in customer repurchase agreements	54,761	(34,405)
Cash dividends on common stock	(74,068)	(70,092)
Repurchase of common stock	(92,687)	(1,535)
Proceeds from exercise of stock options	168	2,212
Net cash provided by (used in) financing activities	2,362,080	(412,066)
Net increase in cash and cash equivalents	1,299,435	273,600
Cash and cash equivalents, beginning of period	185,518	163,948
Cash and cash equivalents, end of period	1,484,953	437,548
Reconciliation of Net Earnings to Net Cash Provided by Operating Activities
Net earnings	127,103	156,546
Adjustments to reconcile net earnings to net cash provided by operating activities:
Gain on sale of investment securities, net	0	(5)
Gain on eminent domain condemnation, net	0	(5,685)
Gain on sale of building, net	(1,680)	(4,545)
Gain on sale of other real estate owned	0	(105)
Increase in BOLI	(4,028)	(5,592)
Net amortization of premiums and discounts on investment securities	10,181	7,593
Accretion of discount for acquired loans, net	(13,106)	(22,369)
Provision for credit losses	23,500	5,000
Valuation allowance on other real estate owned	700	0
Stock-based compensation	4,373	3,792
Depreciation and amortization, net	2,173	16,993
Change in other assets and liabilities	(11,197)	(4,213)
Total adjustments	10,916	(9,136)
Net cash provided by operating activities	138,019	147,410
Supplemental Disclosure of Non-cash Investing Activities
Transfer of loans to other real estate owned	$ 0	$ 9,450