Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 335,515	$ 333,559
Other comprehensive income before reclassifications	$ (244)	$ (47)	(2,422)	143
Amounts reclassified from accumulated other comprehensive income	410	0	(199)	293
Other comprehensive income (loss), net of tax	166	(47)	(2,621)	436	[1]
Ending balance	337,898	340,669	337,898	340,669
Pension and Other Postretirement Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,963)	(1,715)	(2,249)	(2,198)
Other comprehensive income before reclassifications	0	(47)	0	143
Amounts reclassified from accumulated other comprehensive income	288	0	(426)	293
Other comprehensive income (loss), net of tax	288	(47)	(426)	436
Ending balance	(2,675)	(1,762)	(2,675)	(1,762)
Changes in Fair Value of Effective Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,840)	0	(767)	0
Other comprehensive income before reclassifications	(244)	0	(2,422)	0
Amounts reclassified from accumulated other comprehensive income	122	0	227	0
Other comprehensive income (loss), net of tax	(122)	0	(2,195)	0
Ending balance	(2,962)	0	(2,962)	0
Accumulated Other Comprehensive Income/(Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,803)	(1,715)	(3,016)	(2,198)
Other comprehensive income (loss), net of tax			(2,621)	436	[1]
Ending balance	$ (5,637)	$ (1,762)	$ (5,637)	$ (1,762)

[1] Includes the impact of ASU 2018-02, which transferred those amounts from accumulated other comprehensive income (loss) to retained earnings. See Note 16 to the Condensed Consolidated Financial Statements.