Consolidated Balance Sheets (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
ASSETS
Cash and due from banks	$ 355,541us-gaap_CashAndDueFromBanks	$ 444,113us-gaap_CashAndDueFromBanks
Interest-bearing deposits in other financial institutions	488,426us-gaap_InterestBearingDepositsInBanks	571,924us-gaap_InterestBearingDepositsInBanks
Federal funds sold and securities purchased under agreements to resell	3,380	16,030
Investment securities held to maturity, at amortized cost	438,047us-gaap_HeldToMaturitySecurities	404,455us-gaap_HeldToMaturitySecurities
Investment securities available for sale, at fair value	5,358,310us-gaap_AvailableForSaleSecurities	5,396,812us-gaap_AvailableForSaleSecurities
Federal Home Loan Bank and Federal Reserve Bank stocks, at cost	189,222	189,107
Loans held for sale	159,963us-gaap_LoansReceivableHeldForSaleNet	154,935us-gaap_LoansReceivableHeldForSaleNet
Loans	17,979,032	17,593,846
Allowance for loan losses	(265,268)	(266,302)
Loans, net	17,713,764	17,327,544
Premises and equipment, net	274,591us-gaap_PropertyPlantAndEquipmentNet	274,688us-gaap_PropertyPlantAndEquipmentNet
Goodwill	968,774us-gaap_Goodwill	929,168us-gaap_Goodwill
Other intangible assets, net	77,984	67,582
Trading assets	42,336us-gaap_DerivativeAssets	35,163us-gaap_DerivativeAssets
Other assets	998,402us-gaap_OtherAssets	1,010,253us-gaap_OtherAssets
Total assets	27,068,740us-gaap_Assets	26,821,774us-gaap_Assets
LIABILITIES AND STOCKHOLDERS’ EQUITY
Noninterest-bearing demand deposits	4,570,872	4,505,272
Interest-bearing deposits	15,280,720	14,258,232
Total deposits	19,851,592us-gaap_Deposits	18,763,504us-gaap_Deposits
Federal funds purchased and securities sold under agreements to repurchase	587,272	493,991
Other short-term funding	75,265us-gaap_OtherShortTermBorrowings	574,297us-gaap_OtherShortTermBorrowings
Long-term funding	3,429,925us-gaap_LongTermDebt	3,930,117us-gaap_LongTermDebt
Trading liabilities	44,730us-gaap_DerivativeLiabilities	37,329us-gaap_DerivativeLiabilities
Accrued expenses and other liabilities	197,818us-gaap_OtherLiabilities	222,285us-gaap_OtherLiabilities
Total liabilities	24,186,602us-gaap_Liabilities	24,021,523us-gaap_Liabilities
Stockholders’ equity
Preferred equity	59,727	59,727
Common stock	1,674us-gaap_CommonStockValue	1,665us-gaap_CommonStockValue
Surplus	1,505,170	1,484,933
Retained earnings	1,509,967	1,497,818
Accumulated other comprehensive income (loss)	24,800	(4,850)
Treasury stock, at cost	(219,200)us-gaap_TreasuryStockValue	(239,042)us-gaap_TreasuryStockValue
Total stockholders’ equity	2,882,138us-gaap_StockholdersEquity	2,800,251us-gaap_StockholdersEquity
Total liabilities and stockholders’ equity	$ 27,068,740	$ 26,821,774
Preferred shares issued (in shares)	61,356us-gaap_PreferredStockSharesIssued	61,356us-gaap_PreferredStockSharesIssued
Preferred shares authorized (par value $1.00 per share)	750,000us-gaap_PreferredStockSharesAuthorized	750,000us-gaap_PreferredStockSharesAuthorized
Common shares issued (in shares)	167,429,351us-gaap_CommonStockSharesIssued	166,544,252us-gaap_CommonStockSharesIssued
Common shares authorized (par value $0.01 per share)	250,000,000us-gaap_CommonStockSharesAuthorized	250,000,000us-gaap_CommonStockSharesAuthorized
Treasury shares of common stock (in shares)	13,862,507us-gaap_TreasuryStockShares	15,002,318us-gaap_TreasuryStockShares

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669686-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e681-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3