Business Segments - Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income from Operations
Total segment profit	$ 36,514	$ 38,913
Interest expense - net	(4,920)	(6,154)
Other (expense) income	(4,492)	461
Concrete Tie Settlement expense (Note 18)	0	(43,400)
Corporate expense and other unallocated charges	(9,705)	(16,531)
Income (loss) before income taxes	17,397	(26,711)
Assets
Segment Assets	405,171	383,249
Depreciation/Amortization
Depreciation/Amortization	17,631	18,593
Expenditures for Long-Lived Assets
Expenditures for Long-Lived Assets	8,831	5,251
Operating Segments
Income from Operations
Total segment profit	36,514	38,913
Assets
Segment Assets	346,692	363,239
Depreciation/Amortization
Depreciation/Amortization	16,303	17,328
Expenditures for Long-Lived Assets
Expenditures for Long-Lived Assets	8,479	4,949
Unallocated corporate assets
Assets
Segment Assets	58,479	20,010
Depreciation/Amortization
Depreciation/Amortization	1,328	1,265
Expenditures for Long-Lived Assets
Expenditures for Long-Lived Assets	$ 352	$ 302