Restructuring Charges - By segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Restructuring charges
Restructuring charges	$ 743	$ 1,640
Pandemic Restructuring
Restructuring charges
Restructuring charges	605	1,493
2020 Property Restructuring
Restructuring charges
Restructuring charges	7	16
Other Restructuring
Restructuring charges
Restructuring charges	131	131
Corporate
Restructuring charges
Restructuring charges	285	879
Corporate | Pandemic Restructuring
Restructuring charges
Restructuring charges	147	732
Corporate | 2020 Property Restructuring
Restructuring charges
Restructuring charges	7	16
Corporate | Other Restructuring
Restructuring charges
Restructuring charges	131	131
Contract Operations | Operating
Restructuring charges
Restructuring charges	337	616
Contract Operations | Operating | Pandemic Restructuring
Restructuring charges
Restructuring charges	337	616
Aftermarket Services | Operating
Restructuring charges
Restructuring charges	121	145
Aftermarket Services | Operating | Pandemic Restructuring
Restructuring charges
Restructuring charges	$ 121	$ 145