Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities
Net income	$ 123,735	$ 118,043	$ 100,755
Adjustments to reconcile net income to net cash provided by operating activities:
(Reversal)/Provision for credit losses	(3,000)	(9,000)	27,000
(Reversal)/Provision for losses on other real estate owned	(2,122)	10,668	10,385
Deferred tax (benefit)/liability	(15,114)	4,784	13,808
Depreciation	6,690	5,939	6,079
Net gains on sale and transfers of other real estate owned	(1,793)	(369)	(5,243)
Net gains on sale of loans	(879)	(633)	(3,354)
Net gains on sale of loans held for sale			(88)
Proceeds from sale of loans	42,573	59,589	46,377
Originations of loans held for sale	(41,694)	(58,930)	(14,027)
Decrease in unrealized loss from interest rate swaps		(2,634)	(3,874)
Purchase of trading securities	(234)	(163)	(745)
Write-down on venture capital and other investments	409	309	379
Write-down on impaired securities		181	200
Gain on sales and calls of securities	(27,362)	(18,025)	(21,131)
Other non-cash interest expense/(income)	1,100	(200)	(480)
Amortization of security premiums, net	4,425	5,306	4,233
Amortization of other intangible assets	4,657	5,798	5,965
Excess tax short-fall from stock options	2,509	620	290
Stock based and stock issued to officers compensation expense	3,213	2,850	1,758
Noncontrolling interest	(592)	(605)	(605)
Net change in accrued interest receivable and other assets	23,525	43,304	2,622
Net change in other liabilities	(4,973)	(2,256)	3,746
Net cash provided by operating activities	115,073	164,576	174,050
Cash Flows from Investing Activities
Increase in short-term investments	(104,955)	(117,027)	(88,634)
Decrease in securities purchased under agreements to resell			110,000
Purchase of investment securities available-for-sale	(350,130)	(517,513)	(571,093)
Proceeds from maturity and call of investment securities available-for-sale	180,088	552,099	435,000
Proceeds from sale of investment securities available-for-sale	575,358	60,951	524,958
Purchase of mortgage-backed securities available-for-sale	(676,529)	(680,388)	(541,356)
Proceeds from repayment and sale of mortgage-backed securities available-for-sale	669,658	619,169	868,023
Purchase of mortgage-backed securities held-to-maturity			(480,083)
Proceeds from maturity and call of investment securities held-to-maturity	50,973	376,981	163,855
Redemption of Federal Home Loan Bank stock	16,272	11,717	10,884
Net increase in loans	(676,245)	(395,743)	(362,054)
Purchase of premises and equipment	(6,182)	(3,108)	(2,888)
Proceeds from sales of other real estate owned	19,411	47,866	61,406
Net increase in investment in affordable housing	(9,525)	(1,540)	(968)
Net cash (used in)/provided by investing activities	(311,806)	(46,536)	127,050
Cash Flows from Financing Activities
Net change in deposits	596,964	154,275	237,768
Net decrease in federal funds purchased and securities sold under agreements to repurchase	(450,000)	(150,000)	(161,000)
Advances from Federal Home Loan Bank	2,402,000	531,200	4,734,000
Repayment of Federal Home Loan Bank borrowings	(2,027,000)	(610,000)	(5,059,000)
Cash dividends	(12,606)	(16,049)	(16,046)
Redemption of noncontrolling interest	(8,638)
Repayment of subordinated debt	(50,000)
Repayment of other borrowings		(880)	(7,584)
Proceeds from shares issued to Dividend Reinvestment Plan	605	291	287
Proceeds from exercise of stock options	14,755	764	1,306
Excess tax short-fall from share-based payment arrangements	(2,509)	(620)	(290)
Net cash provided by/(used in) financing activities	205,571	(91,019)	(270,559)
Increase in cash and cash equivalents	8,838	27,021	30,541
Cash and cash equivalents, beginning of the year	144,909	117,888	87,347
Cash and cash equivalents, end of the year	153,747	144,909	117,888
Cash paid during the year for:
Interest	84,848	112,411	142,644
Income taxes	55,521	36,083	53,148
Non-cash investing and financing activities:
Net change in unrealized holding (loss)/gain on securities available-for-sale, net of tax	(30,194)	9,197	(7,710)
Transfers to other real estate owned from loans held for investment	22,171	14,389	83,941
Transfers to other real estate owned from loans held for sale			2,874
Loans transferred to loans held for sale		15,986	4,399
Loans transferred to loans held for investment from held for sale		500
Loans to facilitate the sale of other real estate owned	75	1,785	7,472
Loans to facilitate the sale of loans			6,094
Series B Preferred Stock [Member]
Cash Flows from Financing Activities
Redemption of Series B preferred stock	(258,000)
Available-for-sale Securities [Member]
Non-cash investing and financing activities:
Transfers to investment securities available-for-sale at fair value	$ 722,466