Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Cash Flows from Operating Activities
Net income	$ 46,852	$ 66,679
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	25,000	0
Provision for losses on other real estate owned	336	72
Deferred tax provision	(149)	4,333
Depreciation and amortization	1,797	1,626
Amortization of right-of-use asset	2,115	2,071
Change in operating lease liabilities	(1,083)	(1,802)
Net (gains)/loss on sale and transfer of other real estate owned	(4,538)	19
Net gains on sale of loans	(3)	0
Proceeds from sales of loans	239	0
Originations of loans held for sale	(236)	0
Amortization on alternative energy partnerships, venture capital and other investments	13,923	10,812
Net gain on sales and calls of securities	(6)	0
Amortization/accretion of security premiums/discounts, net	1,676	439
Unrealized loss/(gain) on equity securities	6,102	(4,163)
Stock based compensation and stock issued to officers as compensation	1,543	1,534
Net change in accrued interest receivable and other assets	4,126	14,787
Net change in other liabilities	(2,661)	(9,209)
Net cash provided by operating activities	95,033	87,198
Cash Flows from Investing Activities
Purchase of investment securities available-for-sale	(89,989)	(154,924)
Proceeds from sale of investment securities available-for-sale	74,935	0
Proceeds from sale of equity securities	3,113	0
Proceeds from repayments, maturities and calls of investment securities available-for-sale	126,878	74,637
Purchase of Federal Home Loan Bank stock	0	(975)
Redemptions of Federal Home Loan Bank stock	840	975
Net increase in loans	(458,616)	(281,193)
Purchase of premises and equipment	(867)	(1,502)
Proceeds from sales of other real estate owned	881	61
Net increase in investment in affordable housing and alternative energy partnerships	(18,696)	(10,744)
Net cash used for investing activities	(361,521)	(373,665)
Cash Flows from Financing Activities
Net increase in deposits	397,669	383,883
Advances from Federal Home Loan Bank	1,065,000	1,910,000
Repayment of Federal Home Loan Bank borrowings	(1,240,000)	(2,020,000)
Cash dividends paid	(24,659)	(24,967)
Repayment of other borrowings	58	(15,000)
Purchases of treasury stock	(12,880)	(8,601)
Repayment of short-term borrowings	(12,785)	0
Proceeds from shares issued under Dividend Reinvestment Plan	846	835
Taxes paid related to net share settlement of RSUs	(523)	(1,593)
Net cash provided by financing activities	172,726	224,557
Decrease in cash, cash equivalents, and restricted cash	(93,762)	(61,910)
Cash, cash equivalents, and restricted cash, beginning of the period	593,778	600,290	$ 600,290
Cash, cash equivalents, and restricted cash, end of the period	500,016	538,380	$ 593,778
Supplemental disclosure of cash flow information
Interest	51,248	41,754
Income taxes paid	2,642	2,500
Non-cash investing and financing activities:
Net change in unrealized holding loss on securities available-for-sale, net of tax	11,853	8,799
Net change in unrealized holding loss on cash flow hedge derivatives	$ (4,278)	$ (1,224)