Employee Retirement Plans and Postretirement Benefits - Projected Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in projected benefit obligation
Projected benefit obligation, beginning of year	$ 33,178	$ 34,498
Acquisition	48,350	1,063
Service cost	272	841
Interest cost	1,211	802	$ 809
Actuarial loss	(193)	(988)
Benefits paid	(1,779)	(1,113)
Translation adjustment	2,223	(1,925)
Projected benefit obligation, end of year	83,262	33,178	34,498
Changes in fair value of plan assets
Fair value of plan assets, beginning of year	13,433	14,181
Acquisitions	102	981
Actual return on plan assets	380	675
Contributions	644	828
Benefits paid	(1,176)	(1,086)
Actuarial gain	1,064	(1,357)
Translation adjustment	456	(789)
Fair value of plan assets, end of year	14,903	13,433	$ 14,181
Funded status of plan	$ (68,359)	$ (19,745)