Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Cash Flows from Operating Activities
Net income	$ 96,007	$ 75,028
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	8,100	8,643
Deferred tax (benefit)/ provision	(7,293)	3,118
Depreciation and amortization	2,054	2,112
Amortization of right-of-use asset	2,405	2,443
Change in operating lease liabilities	81	(1,744)
Net gains on sale and transfer of other real estate owned	0	(6)
Loss on sales or disposal of fixed assets	6	25
Amortization on alternative energy partnerships, venture capital and other investments	15,594	8,287
Net gain on sale of equity securities	(15)	(100)
Amortization/accretion of security premiums/discounts, net	(1,324)	1,494
Unrealized gain on equity securities	(4,853)	(5,874)
Write-off of AFS debt securities	3,000	0
Stock-based compensation and stock issued to officers as compensation	1,511	1,614
Net change in accrued interest receivable and other assets	15,623	(13,309)
Net change in other liabilities	(9,730)	4,726
Net cash provided by operating activities	121,166	86,457
Cash Flows from Investing Activities
Purchase of investment securities available-for-sale	(156,597)	(204,882)
Proceeds from repayments, maturities and calls of investment securities available-for-sale	104,669	45,393
Proceeds from sale of equity securities	0	553
Purchase of Federal Home Loan Bank stock	(680)	0
Redemption of Federal Home Loan Bank stock	680	0
Net increase in loans	(68,133)	(413,721)
Purchase of premises and equipment	(295)	(1,276)
Proceeds from sales of other real estate owned	0	307
Net (increase)/decrease in investment in affordable housing and alternative energy partnerships	(8,078)	902
Acquisition, net of cash acquired	0	(73,882)
Net cash used for investing activities	(128,434)	(646,606)
Cash Flows from Financing Activities
Increase/(decrease) in deposits	143,633	(573,720)
Advances from Federal Home Loan Bank	(125,000)	0
Cash dividends paid	(24,605)	(25,515)
Purchases of treasury stock	(16,736)	(32,896)
Proceeds from shares issued under Dividend Reinvestment Plan	918	945
Taxes paid related to net share settlement of RSUs	(14)	(285)
Net cash used by financing activities	(21,804)	(631,471)
Decrease in cash, cash equivalents, and restricted cash	(29,072)	(1,191,620)
Cash, cash equivalents, and restricted cash, beginning of the period	1,162,402	2,449,704	$ 2,449,704
Cash, cash equivalents, and restricted cash, end of the period	1,133,330	1,258,084	$ 1,162,402
Supplemental disclosure of cash flow information
Interest	86,785	12,896
Income taxes paid	0	1,281
Non-cash investing and financing activities:
Net change in unrealized holding gain/(loss) on securities available-for-sale, net of tax	11,659	(45,966)
Net unrealized gain (1)	$ (441)	$ 3,054