Accumulated Other Comprehensive Income (Loss), Effect on Net Income of Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 4,619		$ 5,749	$ 6,275
Income tax provision	5,286		5,383	5,042
Prior service credits	(944)		7,230	161
Actuarial loss	(1,255)		(1,544)	1,205
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications of period, net of tax	(124)
Gains and Losses on Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	106
Income tax provision	43
Net of tax	63
Amortization of Benefit Pension Items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credits	944	[1]
Actuarial loss	(1,255)	[1]
Total before tax	(311)
Income tax provision	124
Net of tax	$ (187)

[1] These accumulated other comprehensive income components are included in the computation of net periodic benefit cost. See Note 10 "Employee Retirement Benefits."