Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Flows from Operating Activities
Net income	$ 48,941,000	$ 46,163,000
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Credit for loan losses	(2,500,000)	(10,500,000)
Provision for losses on other real estate owned	272,000	128,000
Deferred tax liability	14,283,000	13,315,000
Depreciation and amortization	1,769,000	1,923,000
Net gains on sale and transfer of other real estate owned	(219,000)
Net gains on sale of loans		(102,000)
Proceeds from sales of loans	7,500,000	3,391,000
Originations of loans held-for-sale		(3,289,000)
Amortization on alternative energy partnerships, venture capital and other investments	187,000	1,304,000
Net loss on sales and calls of securities	438,000
Amortization/accretion of security premiums/discounts, net	727,000	1,527,000
Write-down on impaired securities	28,000	206,000
Stock based compensation and stock issued to officers as compensation	1,183,000	1,578,000
Net change in accrued interest receivable and other assets	(5,617,000)	(7,328,000)
Net change in other liabilities	(12,926,000)	(7,207,000)
Net cash provided by operating activities	54,066,000	41,109,000
Cash Flows from Investing Activities
Decrease in short-term investments	337,009,000	104,496,000
Purchase of investment securities available-for-sale	(99,965,000)	(25,898,000)
Proceeds from sale of investment securities available-for-sale	99,541,000
Proceeds from repayments, maturities and calls of investment securities available-for-sale	85,439,000	143,464,000
Net increase in loans	(170,843,000)	(174,402,000)
Purchase of premises and equipment	(1,016,000)	(1,063,000)
Proceeds from sales of other real estate owned	878,000
Net decrease/(increase) in investment in affordable housing and alternative energy partnerships	565,000	(22,326,000)
Net cash provided by investing activities	251,608,000	24,271,000
Cash Flows from Financing Activities
Net decrease in deposits	(87,333,000)	(184,803,000)
Net decrease in federal funds purchased and securities sold under agreements to repurchase	(200,000,000)
Advances from Federal Home Loan Bank	250,000,000	450,000,000
Repayment of Federal Home Loan Bank borrowings	(275,000,000)	(250,000,000)
Cash dividends paid	(16,756,000)	(14,183,000)
Purchases of treasury stock		(54,441,000)
Proceeds from shares issued under Dividend Reinvestment Plan	617,000	545,000
Proceeds from exercise of stock options	422,000	49,000
Taxes paid related to net share settlement of RSUs	(5,118,000)	(35,000)
Net cash used in financing activities	(333,169,000)	(52,868,000)
(Decrease)/increase in cash and cash equivalents	(27,495,000)	12,512,000
Cash and cash equivalents, beginning of the period	218,017,000	180,130,000
Cash and cash equivalents, end of the period	190,522,000	192,642,000
Supplemental disclosure of cash flow information
Interest	20,495,000	20,310,000
Income taxes paid	15,896,000	4,789,000
Non-cash investing and financing activities:
Net change in unrealized holding gain on securities available-for-sale, net of tax	(226,000)	10,473,000
Net change in unrealized holding loss on cash flow hedge derivatives	299,000	(3,120,000)
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		6,676,000
Loans transferred from held for investment to held for sale, net	$ 5,835,000