Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities
Net income	$ 46,163,000	$ 35,980,000
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Credit for loan losses	(10,500,000)	(5,000,000)
Provision for losses on other real estate owned	128,000	181,000
Deferred tax liability	13,315,000	6,840,000
Depreciation and amortization	1,923,000	1,929,000
Net losses on sale and transfer of other real estate owned		154,000
Net gains on sale of loans	(102,000)	(596,000)
Proceeds from sales of loans	3,391,000	10,360,000
Originations of loans held-for-sale	(3,289,000)	(8,791,000)
Amortization on alternative energy partnerships, venture capital and other investments	1,304,000	224,000
Net losses on sales and calls of securities		21,000
Amortization/accretion of security premiums/discounts, net	1,527,000	502,000
Write-down on impaired securities	206,000
Excess tax short-fall from share-based payment arrangements		4,395,000
Stock based compensation and stock issued to officers as compensation	1,578,000	1,570,000
Net change in accrued interest receivable and other assets	(7,328,000)	6,631,000
Net change in other liabilities	(7,207,000)	1,379,000
Net cash provided by operating activities	41,109,000	55,779,000
Cash Flows from Investing Activities
Decrease/(increase) in short-term investments	104,496,000	(129,112,000)
Purchase of investment securities available-for-sale	(25,898,000)	(703,305,000)
Proceeds from sale of investment securities available-for-sale		741,992,000
Proceeds from repayments, maturities and calls of investment securities available-for-sale	143,464,000	12,102,000
Redemptions of Federal Home Loan Bank stock		5,785,000
Net increase in loans	(174,402,000)	(305,651,000)
Purchase of premises and equipment	(1,063,000)	(562,000)
Proceeds from sales of other real estate owned		1,043,000
Investment in affordable housing and alternative energy partnerships	(22,326,000)	(1,351,000)
Net cash provided by/(used in) investing activities	24,271,000	(379,059,000)
Cash Flows from Financing Activities
Net (decrease)/increase in deposits	(184,803,000)	329,724,000
Net decrease in federal funds purchased and securities sold under agreements to repurchase		(50,000,000)
Advances from Federal Home Loan Bank	450,000,000	2,242,000,000
Repayment of Federal Home Loan Bank borrowings	(250,000,000)	(2,182,000,000)
Cash dividends paid	(14,183,000)	(7,983,000)
Purchase of treasury stock	(54,441,000)
Proceeds from shares issued under Dividend Reinvestment Plan	545,000	1,289,000
Proceeds from exercise of stock options	49,000	88,000
Taxes paid related to net share settlement of RSUs	(35,000)	(114,000)
Excess tax short-fall from share-based payment arrangements		(4,395,000)
Net cash provided by/(used in) financing activities	(52,868,000)	328,609,000
Increase in cash and cash equivalents	12,512,000	5,329,000
Cash and cash equivalents, beginning of the period	180,130,000	176,830,000
Cash and cash equivalents, end of the period	192,642,000	182,159,000
Cash paid during the period:
Interest	20,310,000	17,370,000
Income taxes paid	4,789,000	11,884,000
Non-cash investing and financing activities:
Net change in unrealized holding gain on securities available-for-sale, net of tax	10,473,000	6,511,000
Net change in unrealized holding loss on cash flow hedge derivatives	(3,120,000)	(1,588,000)
Transfers to other real estate owned from loans held for investment	2,698,000	$ 701,000
Loans transferred from held for sale to held for investment, net	$ 6,676,000