Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Interest expense	$ 1,139	$ 1,411
Selling, general and administrative expenses	7,449	6,706
Income tax provision	1,094	1,567
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Net of tax	83
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	21
Income tax provision	(8)
Net of tax	13
Amortization of Benefit Pension Items [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Selling, general and administrative expenses	116
Income tax provision	(46)
Net of tax	70
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
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)