Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities
Net income	$ 80,994,000	$ 81,180,000
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Credit for loan losses	(15,650,000)	(7,150,000)
Provision for losses on other real estate owned	383,000	368,000
Deferred tax liability	7,098,000	8,797,000
Depreciation and amortization	3,861,000	6,864,000
Net gains on sale and transfer of other real estate owned	(228,000)	(2,003,000)
Net gains on sale of loans	(201,000)	(763,000)
Proceeds from sales of loans	6,065,000	19,170,000
Originations of loans held-for-sale	(8,789,000)	(17,433,000)
Amortization on alternative energy partnerships, venture capital and other investments	25,264,000	327,000
Net gain on sales and calls of securities	(1,655,000)	(522,000)
Amortization/accretion of security premiums/discounts, net	3,404,000	1,770,000
Write-down on impaired securities	206,000	3,875,000
Excess tax short-fall from share-based payment arrangements		5,619,000
Stock based compensation and stock issued to officers as compensation	2,623,000	2,738,000
Net change in accrued interest receivable and other assets	(4,690,000)	(15,041,000)
Net change in other liabilities	(7,212,000)	(1,423,000)
Net cash provided by operating activities	91,473,000	86,373,000
Cash Flows from Investing Activities
Decrease/(increase) in short-term investments	(170,047,000)	440,903,000
Purchase of investment securities available-for-sale	(290,901,000)	(1,223,504,000)
Proceeds from sale of investment securities available-for-sale	241,844,000	958,656,000
Proceeds from repayments, maturities and calls of investment securities available-for-sale	415,656,000	36,512,000
Redemptions of Federal Home Loan Bank stock		13,535,000
Net increase in loans	(350,810,000)	(581,379,000)
Purchase of premises and equipment	(1,857,000)	(1,383,000)
Proceeds from sales of other real estate owned	828,000	10,139,000
Investment in affordable housing and alternative energy partnerships	(47,420,000)	(19,590,000)
Net cash used in investing activities	(202,707,000)	(366,111,000)
Cash Flows from Financing Activities
Net (decrease)/increase in deposits	(37,711,000)	555,369,000
Net decrease in federal funds purchased and securities sold under agreements to repurchase		(50,000,000)
Advances from Federal Home Loan Bank	1,755,000,000	4,632,000,000
Repayment of Federal Home Loan Bank borrowings	(1,475,000,000)	(4,847,000,000)
Cash dividends paid	(28,375,000)	(19,170,000)
Purchases of treasury stock	(54,441,000)
Proceeds from shares issued under Dividend Reinvestment Plan	1,096,000	2,752,000
Proceeds from exercise of stock options	49,000	1,713,000
Taxes paid related to net share settlement of RSUs	(103,000)	(204,000)
Excess tax short-fall from share-based payment arrangements		(5,619,000)
Net cash provided by financing activities	160,515,000	269,841,000
Increase/(decrease) in cash and cash equivalents	49,281,000	(9,897,000)
Cash and cash equivalents, beginning of the period	180,130,000	176,830,000
Cash and cash equivalents, end of the period	229,411,000	166,933,000
Supplemental disclosure of cash flow information
Interest	40,740,000	34,505,000
Income taxes paid	30,698,000	43,534,000
Non-cash investing and financing activities:
Net change in unrealized holding gain on securities available-for-sale, net of tax	13,970,000	2,046,000
Net change in unrealized holding loss on cash flow hedge derivatives	4,402,000	740,000
Transfers to other real estate owned from loans held for investment	2,698,000	866,000
Loans transferred from held for sale to held for investment, net	$ 3,751,000