Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax provision on comprehensive income	$ (8,080)	$ (94)
Reclassifications out of other comprehensive income (loss) | Retirement plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of gain/loss and settlement loss	2,042	247
Income tax provision on comprehensive income	(776)	(94)
Total	$ 1,266	$ 153