Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Cash Flows [Abstract]
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 36,064	$ 23,985
INVESTING ACTIVITIES
Net (increase) decrease in loans	(94,812)	3,446
Securities available-for-sale:
Proceeds from sales	560,676	3,155
Proceeds from maturities, prepayments and calls	52,783	53,631
Purchases of securities	(405,998)	(77,725)
Securities held-to-maturity:
Proceeds from maturities, prepayments and calls	9,430	12,325
Purchases of securities	(51,246)	(12,240)
Proceeds from bank-owned life insurance	1,185
Cash paid to acquire a business, net of cash acquired	(28,551)
Purchases of premises and equipment - net	(2,033)	(1,485)
Net cash provided by (used in) investing activities	41,434	(18,893)
FINANCING ACTIVITIES
Increase in deposits	120,954us-gaap_IncreaseDecreaseInDeposits	153,387us-gaap_IncreaseDecreaseInDeposits
Proceeds from Federal Home Loan Bank borrowings	325,000
Repayment of Federal Home Loan Bank borrowings	(507,982)	(16,181)
Decrease in other short-term borrowings	(9,060)	(37,682)
Decrease in federal funds purchased		(20,000)
Dividends paid to common shareholders	(6,446)us-gaap_PaymentsOfDividendsCommonStock	(5,833)us-gaap_PaymentsOfDividendsCommonStock
Treasury shares (purchased) sold - net	(992)	862
Net cash (used in) provided by financing activities	(78,526)	74,553
Net (decrease) increase in cash and cash equivalents	(1,028)	79,645
Cash and cash equivalents at beginning of the period	94,002	95,551
Cash and cash equivalents at end of the period	92,974	175,196
SUPPLEMENTAL DISCLOSURES
Interest paid on deposits and other borrowings	5,522us-gaap_InterestPaid	6,589us-gaap_InterestPaid
Income taxes paid	100us-gaap_IncomeTaxesPaid
Transfers of loans to other real estate owned	344us-gaap_TransferToOtherRealEstate	1,287us-gaap_TransferToOtherRealEstate
Non-cash transactions related to ESB acquisition	$ 301,933

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.