Accumulated Other Comprehensive Income (Loss) (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
Accumulated Other Comprehensive Income Loss [Line Items]
Interest expense	$ 1,131	$ 1,599	$ 2,270	$ 3,010
Income tax provision	1,567	1,164	2,661	2,731
Selling, general and administrative expenses	7,047	7,441	14,496	14,147
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Net of tax	85		168
Gains and Losses on Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest expense	25		46
Income tax provision	(10)		(18)
Net of tax	15		28
Amortization of Benefit Pension Items [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Income tax provision	(46)		(92)
Selling, general and administrative expenses	116		232
Net of tax	70		140
Amortization of Benefit Pension Items [Member] | Prior Service Costs [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Selling, general and administrative expenses	236		472
Amortization of Benefit Pension Items [Member] | Actuarial Gains (Losses) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Selling, general and administrative expenses	$ (120)		$ (240)