Business Segments - Additional Information (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) segment	Dec. 31, 2018 USD ($) segment
Segment Reporting Information [Line Items]
Total identifiable assets	$ 45,701	$ 41,685
Number of operating segments | segment	2	2
Operating Segments | ATG
Segment Reporting Information [Line Items]
Total identifiable assets	$ 36,339	$ 31,639
Operating Segments | CPG
Segment Reporting Information [Line Items]
Total identifiable assets	$ 9,362	$ 10,046