Reclassifications Out of Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Income Note [Line Items]
Unrealized (losses) gains on available-for-sale securities	$ (116)	$ (557)
Amortization of gains included in net income on available-for-sale securities transferred to held to maturity	(319)	(413)
Gains included in net income on derivative financial instruments accounted for as cash flow hedges	(538)	(1,600)
Prior service cost	90
Net gain/loss	42
Reclassification of unamortized prior service cost and actuarial losses, Before-tax Amount	132	154
Interest Rate Contracts | Loan Interest Revenue
Other Comprehensive Income Note [Line Items]
Gains included in net income on derivative financial instruments accounted for as cash flow hedges	(537)
Interest Rate Contracts | Other Fee Revenue
Other Comprehensive Income Note [Line Items]
Gains included in net income on derivative financial instruments accounted for as cash flow hedges	$ (1)