Changes in AOCLoss - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net	$ 2,872	$ 2,454
Tax expense (benefit)	3,328	220
Reclassification net of tax	(5,208)	(378)
Other Postretirement Benefit Liability | Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses	(32)	(17)
Tax expense (benefit)	12	6
Reclassification net of tax	(20)	(11)
Pension Liability | Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses	181	255
Tax expense (benefit)	(68)	(96)
Reclassification net of tax	113	$ 159
Unrealized Net Loss on Interest Rate Swap | Interest rate swap
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net	97
Tax expense (benefit)	(37)
Reclassification net of tax	$ 60