Changes in Accumulated Other Comprehensive Loss by Component (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net	$ 2,130	$ 2,080	$ 6,190	$ 6,304
Tax expense (benefit)	91	745	1,304	3,525
Reclassification net of tax	(594)	(2,327)	(3,063)	(7,000)
Other Postretirement Benefit Liability | Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses			(129)
Tax expense (benefit)			48
Reclassification net of tax			(81)
Pension Liability | Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses			905
Tax expense (benefit)			(336)
Reclassification net of tax			569
Realized losses on cash flow hedges | Interest rate swap | Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net			222
Tax expense (benefit)			(82)
Reclassification net of tax			$ 140