Accumulated Other Comprehensive Loss (Reclassifications out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Long-term obligations	$ 204,882		$ 220,952
Securities gains (losses)	58		(45)
Amounts reclassified from accumulated other comprehensive income, net of tax	3,076	[1]	2,151	[1]
Unrealized Loss on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Long-term obligations	(813)	[1]	(749)	[1]
Income taxes	321	[1]	296	[1]
Amounts reclassified from accumulated other comprehensive income, net of tax	492	[1],[2]	453	[1],[2]
Unrealized Gains on Investment Securities Available for Sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Securities gains (losses)	58	[1]
Income taxes	(23)	[1]
Amounts reclassified from accumulated other comprehensive income, net of tax	(35)	[1],[2]	0	[2]
Defined Benefit Pension Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Employee Benefits, prior service costs	(52)	[1]	(53)	[1]
Employee Benefits, actuarial gains	(4,252)	[1]	(2,737)	[1]
Total before taxes	(4,304)		(2,790)	[1]
Income taxes	1,685	[1]	1,092	[1]
Amounts reclassified from accumulated other comprehensive income, net of tax	$ 2,619	[1],[2]	$ 1,698	[1],[2]

[1] Amounts in parentheses indicate debits to profit/loss.

[2] All amounts are net of tax. Amounts in parentheses indicate debits.