Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Net income	$ 150,102,000	$ 127,084,000
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Reversal for loan losses	(2,500,000)	(15,650,000)
Provision for losses on other real estate owned	889,000	176,000
Deferred tax liability	10,319,000	22,483,000
Depreciation and amortization	5,416,000	5,684,000
Net gains on sale and transfer of other real estate owned	(394,000)	(476,000)
Net gains on sale of loans		(285,000)
Proceeds from sales of loans	7,500,000	13,525,000
Originations of loans held-for-sale		(12,665,000)
Amortization on alternative energy partnerships, venture capital and other investments	2,778,000	27,282,000
Net loss/(gain) on sales and calls of securities	438,000	(3,347,000)
Amortization/accretion of security premiums/discounts, net	990,000	5,193,000
Loss on sales or disposal of fixed assets		19,000
Write-down on impaired securities		206,000
Stock based compensation and stock issued to officers as compensation	4,449,000	3,804,000
Net change in accrued interest receivable and other assets	(51,776,000)	2,101,000
Gain on acquisition	(5,440,000)
Net change in other liabilities	828,000	(4,537,000)
Net cash provided by operating activities	123,599,000	170,597,000
Cash Flows from Investing Activities
Decrease/(increase) in short-term investments	516,008,000	(254,877,000)
Purchase of investment securities available-for-sale	(450,745,000)	(690,966,000)
Proceeds from sale of investment securities available-for-sale	99,541,000	415,543,000
Proceeds from repayments, maturities and calls of investment securities available-for-sale	389,829,000	585,285,000
Purchase of Federal Home Loan Bank stock		(1,650,000)
Redemptions of Federal Home Loan Bank stock	6,459,000
Net increase in loans	(686,225,000)	(853,453,000)
Purchase of premises and equipment	(976,000)	(3,166,000)
Proceeds from sales of premises and equipment		11,000
Proceeds from sales of other real estate owned	2,186,000	6,713,000
Net increase in investment in affordable housing and alternative energy partnerships	(20,867,000)	(59,844,000)
Acquisition, net of cash acquired	(14,309,000)
Net cash used for investing activities	(159,099,000)	(856,404,000)
Cash Flows from Financing Activities
Net (decrease)/increase in deposits	73,120,000	429,976,000
Net decrease in federal funds purchased and securities sold under agreements to repurchase	(250,000,000)	(50,000,000)
Advances from Federal Home Loan Bank	2,608,000,000	2,730,000,000
Repayment of Federal Home Loan Bank borrowings	(2,393,000,000)	(2,305,000,000)
Cash dividends paid	(50,491,000)	(42,570,000)
Purchases of treasury stock		(54,441,000)
Proceeds from shares issued under Dividend Reinvestment Plan	1,849,000	1,643,000
Proceeds from exercise of stock options	1,018,000	49,000
Taxes paid related to net share settlement of RSUs	(5,127,000)	(103,000)
Net cash (used in) provided by financing activities	(14,631,000)	709,554,000
(Decrease)/increase in cash and cash equivalents	(50,131,000)	23,747,000
Cash and cash equivalents, beginning of the period	218,017,000	180,130,000
Cash and cash equivalents, end of the period	167,886,000	203,877,000
Supplemental disclosure of cash flow information
Interest	58,416,000	61,212,000
Income taxes paid	62,296,000	31,717,000
Non-cash investing and financing activities:
Net change in unrealized holding gain on securities available-for-sale, net of tax	3,592,000	13,927,000
Net change in unrealized holding loss on cash flow hedge derivatives	(94,000)	(3,598,000)
Transfers to other real estate owned from loans held for investment	726,000	2,698,000
Loans transferred from held for sale to held for investment, net		1,351,000
Loans to facilitate the sale of other real estate owned		2,616,000
Issuance of stock related to acquisition