Accumulated Other Comprehensive Loss - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Unrecognized Net Defined Benefit and Postretirement Plan Costs
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification adjustment from AOCI on unrecognized net defined benefit and postretirement plan costs	$ 600,000	$ 700,000
Reclassification adjustment from AOCI on unrecognized net defined benefit and postretirement plan costs, tax	200,000	200,000
Change in Fair Value of Derivatives Products
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification adjustment from AOCI on derivatives, net gains (losses)	(600,000)	3,400,000
Reclassification adjustment from AOCI on derivatives, tax	$ 0	$ 1,200,000