Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities
Net income	$ 211,758	$ 207,237
Adjustments to reconcile net income to net cash provided by operating activities:
Reversal for credit losses	(2,000)	(4,500)
Provision for losses on other real estate owned	494	0
Deferred tax liability	9,911	2,342
Depreciation and amortization	5,009	5,593
Amortization of right-of-use asset	6,248	0
Change in operating lease liabilities	(5,298)	0
Net gains on sale and transfer of other real estate owned	(193)	(567)
Net gains on sale of held-for-sale loans	(795)	0
Proceeds from sales of held-for sale loans	38,742	8,000
Amortization on alternative energy partnerships, venture capital and other investments	27,009	5,384
Net (gain)/loss on sales and calls of securities	108	14
Amortization/accretion of security premiums/discounts, net	2,376	2,371
Loss on sales or disposal of fixed assets	0	107
Unrealized (gain)/loss on equity securities	(7,764)	4,580
Stock based compensation and stock issued to officers as compensation	5,597	5,976
Net change in accrued interest receivable and other assets	(31,640)	(7,863)
Gain on acquisition	0	(340)
Net change in other liabilities	64,186	10,998
Net cash provided by operating activities	323,748	239,332
Cash Flows from Investing Activities
Decrease in interest-bearing deposits	0	5,000
Purchase of investment securities available-for-sale	(539,979)	(448,805)
Proceeds from sale of investment securities available-for-sale	149,725	99,644
Proceeds from repayments, maturities and calls of investment securities available-for-sale	233,058	346,328
Purchase of Federal Home Loan Bank stock	(975)	(5,430)
Redemptions of Federal Home Loan Bank stock	975	11,265
Net increase in loans	(803,291)	(771,290)
Purchase of premises and equipment	(5,125)	(4,496)
Proceeds from sales of other real estate owned	1,905	3,302
Net increase in investment in affordable housing and alternative energy partnerships	(35,952)	(36,666)
Net cash used for investing activities	(999,659)	(801,148)
Cash Flows from Financing Activities
Net increase in deposits	955,679	890,823
Net decrease in federal funds purchased and securities sold under agreements to repurchase	0	(100,000)
Advances from Federal Home Loan Bank	3,610,000	4,495,000
Repayment of Federal Home Loan Bank borrowings	(3,540,000)	(4,610,000)
Cash dividends paid	(74,422)	(58,498)
Repayment of other borrowings	(39,918)	(37,117)
Proceeds from other borrowings	25,507	29,554
Purchases of treasury stock	(36,301)	0
Proceeds from shares issued under Dividend Reinvestment Plan	2,522	1,982
Proceeds from exercise of stock options	0	838
Taxes paid related to net share settlement of RSUs	(2,300)	(3,550)
Net cash provided by financing activities	900,767	609,032
Decrease in cash, cash equivalents, and restricted cash	224,856	47,216
Cash, cash equivalents, and restricted cash, beginning of the period	600,290	534,801
Cash, cash equivalents, and restricted cash, end of the period	825,146	582,017
Supplemental disclosure of cash flow information
Interest	137,422	79,877
Income taxes paid	43,507	48,072
Non-cash investing and financing activities:
Net change in unrealized holding loss on securities available-for-sale, net of tax	21,292	(16,793)
Net change in unrealized holding loss on cash flow hedge derivatives	(4,119)	4,595
Transfers to other real estate owned from loans held for investment	860	1,646
Loans transferred from held for investment to held for sale, net	$ 75,285	$ 0