Accumulated Other Comprehensive Income (Loss) - Reclassifications of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	$ 71	$ (474)	$ (1,671)	$ (2,901)
Prior service cost
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI before tax	114	0	352	0
Actuarial losses
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI before tax	0	(730)	(3,058)	(4,462)
Pension and Postretirement Plans
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI before tax	114	(730)	(2,706)	(4,462)
Income tax expense	(43)	256	1,035	1,561
Total reclassifications for the period	$ 71	$ (474)	$ (1,671)	$ (2,901)