Business Segments - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information
Assets	$ 359,803	$ 370,395
Operating Segments \| Rail Technologies and Services
Segment Reporting Information
Assets	169,242	161,485
Operating Segments \| Infrastructure Solutions
Segment Reporting Information
Assets	119,184	137,519
Unallocated corporate assets
Segment Reporting Information
Assets	$ 71,377	$ 71,391

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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+ Details