Accumulated Other Comprehensive Income (Loss) (AOCI Reclass to IS) (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (46,897)	$ (48,675)
Income Before Provision for Income Taxes	54,454	51,951
Tax Benefit (Expense)	(15,862)	(15,971)
Net Income	38,592	35,980
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net Income	46	1,800
Amortization of Holding Gains on Investment Securities Transferred from Available-for-Sale to Held-to-Maturity | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Investment Income, Interest	333	3,307
Tax Benefit (Expense)	(131)	(1,304)
Net Income	202	2,003
Amortization of Defined Benefit Pension Items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Income Before Provision for Income Taxes	(258)	(334)
Tax Benefit (Expense)	102	131
Net Income	(156)	(203)
Prior Service Credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	81	80
Net Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Benefits	$ (339)	$ (414)