Pension and Other Postretirement Benefits - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss (gain), beginning of year	$ 48,395
Amortization of actuarial gain (loss)	(1,432)
Actuarial loss	39,329
Asset gain	(30,197)
Settlement gain recognized	(7)	$ (1,300)
Currency impact	644
Net actuarial loss (gain), end of year	56,746	48,395
Prior service cost, beginning of year	2,725
Amortization of prior service cost	(169)	42	$ 41
Currency impact	105
Prior service cost, end of year	2,661	2,725
Other Benefits
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss (gain), beginning of year	(3,047)
Amortization of actuarial gain (loss)	133
Actuarial loss	2,374
Asset gain	0
Settlement gain recognized	0
Currency impact	(60)
Net actuarial loss (gain), end of year	(600)	(3,047)
Prior service cost, beginning of year	0
Amortization of prior service cost	0		$ 0
Currency impact	0
Prior service cost, end of year	$ 0	$ 0