Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash Flows from Operating Activities
Interest and dividends received	$ 236,887	$ 200,495
Service charges and other fees received	22,642	18,083
Interest paid	(2,373)	(3,572)
Net cash paid to vendors, employees and others	(95,770)	(97,222)
Income taxes	(32,998)	(47,085)
Net cash provided by operating activities	128,388	70,699
Cash Flows from Investing Activities
Proceeds from redemption of FHLB stock	4,712
Net change in interest-earning balances from depository institutions	28,617	17,305
Proceeds from repayment of investment securities available-for-sale	282,175	424,999
Proceeds from maturity of investment securities available-for-sale	1,226
Purchases of investment securities available-for-sale	(1,092,577)	(949,645)
Proceeds from repayment and maturity of investment securities held-to-maturity	213,907	82,937
Purchases of investment securities held-to-maturity	(532,474)	(545,681)
Increase decrease (increase) in equity investments	511	(5,692)
Net (increase) decrease in loan and lease finance receivables	(20,423)	297,796
Proceeds from sale of building, net of selling costs	8,315	1,157
Purchase of premises and equipment	(2,307)	(2,299)
Purchase of BOLI		(25,000)
Proceeds from BOLI death benefit	3,096	11,121
Proceeds from sales of other real estate owned		3,869
Cash acquired from acquisition, net of cash paid	329,001
Net cash used in investing activities	(776,221)	(689,133)
Cash Flows from Financing Activities
Net (decrease) increase in other deposits	(38,815)	968,729
Net (decrease) increase in time deposits	(47,979)	(36,173)
Net decrease in other borrowings	(2,281)	(5,000)
Net (decrease) increase in customer repurchase agreements	(139,559)	138,801
Repayment of junior subordinated debentures		(25,774)
Cash dividends on common stock	(49,873)	(48,874)
Repurchase of common stock	(40,464)	(534)
Repurchase of common stock, ASR Plan	(70,000)
Proceeds from exercise of stock options	965	964
Net cash (used in) provided by financing activities	(388,006)	992,139
Net (decrease) increase in cash and cash equivalents	(1,035,839)	373,705
Cash and cash equivalents, beginning of period	1,732,548	1,958,160
Cash and cash equivalents, end of period	696,709	2,331,865
Reconciliation of Net Earnings to Net Cash Provided by Operating Activities
Net earnings	104,618	115,072
Adjustments to reconcile net earnings to net cash provided by operating activities:
Gain on sale of building, net	(2,717)	(189)
Gain on sale of other real estate owned		(477)
Increase in BOLI	(1,952)	(5,864)
Net amortization of premiums and discounts on investment securities	15,353	14,908
Accretion of discount for acquired loans, net	(3,693)	(7,511)
Provision for (recapture of) credit losses	6,100	(21,500)
(Recapture of) provision for unfunded loan commitments	0	(1,000)
Stock-based compensation	3,577	2,672
Depreciation and amortization, net	5,749	(4,838)
Change in other assets and liabilities	1,353	(20,574)
Total adjustments	23,770	(44,373)
Net cash provided by operating activities	128,388	70,699
Supplemental Disclosure of Non-cash Investing Activities
Securities purchased and not settled	80,230	110,430
Issuance of common stock for acquisition	$ 197,069