Reclassifications Out of Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other Comprehensive Income Note [Line Items]
Unrealized (losses) gains on available-for-sale securities, securities gains, net, before tax		$ 6,490	$ 116	$ 7,047
Reclassification adjustment for gains included in net income, tax (expense) or benefit		(2,425)	(45)	(2,631)
Unrealized (losses) gains on available-for-sale securities, securities gains, net of tax		4,065	71	4,416
Amortization of gains included in net income on available-for-sale securities transferred to held to maturity, investment securities interest revenue, before tax	271	400	590	813
Amortization of gains included in net income on available-for-sale securities transferred to held to maturity, investment securities interest revenue, tax (expense) or benefit	(103)	(151)	(227)	(308)
Amortization of gains included in net income (loss) on available for sale securities transferred to held to maturity, Net of Tax Amount	168	249	363	505
Gains included in net income on derivative financial instruments accounted for as cash flow hedges, before tax	306	714	844	2,314
Gains included in net income on derivative financial instruments accounted for as cash flow hedges, tax (expense) or benefit	(119)	(278)	(328)	(900)
Gains included in net income on derivative financial instruments accounted for as cash flow hedges, tax (expense) or benefit, net of tax	187	436	516	1,414
Prior service cost	(91)		(181)
Actuarial losses	(42)		(84)
Amortization of prior service cost and actuarial losses included in net periodic pension cost for defined benefit pension plan, total before tax	(133)		(265)
Amortization of prior service cost and actuarial losses included in net periodic pension cost for defined benefit pension plan, tax (expense) or benefit	52		103
Amortization of prior service cost and actuarial losses included in net periodic pension cost for defined benefit pension plan, net of tax	(81)		(162)
Total reclassifications for the period	274		788
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, before tax	303		840
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, before tax	$ 3		$ 4