Accumulated Other Comprehensive Income (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Tax Expense (Benefit)	$ (15,971)	$ (16,662)
Income Before Provision for Income Taxes	51,951	60,472
Reclassifications for the Period, Net of Tax	35,980	43,810
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications for the Period, Net of Tax	1,800
Amortization of Holding Gains on Investment Securities Transferred from Available-for-Sale to Held-to-Maturity [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of Unrealized Holding Gains on Investment Securities Transferred from Available-for-Sale to Held-to-Maturity	3,307
Tax Expense (Benefit)	(1,304)
Reclassifications for the Period, Net of Tax	2,003
Amortization of Defined Benefit Pension Items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Tax Expense (Benefit)	131
Income Before Provision for Income Taxes	(334)
Amortization of Defined Benefit Pension Items, Prior Service Credit, before tax	80
Amortization of Defined Benefit Pension Items, Net Actuarial Losses, before tax	(414)
Reclassifications for the Period, Net of Tax	$ (203)