Reportable Segments - Summarized Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 28, 2020	Mar. 30, 2019	Dec. 28, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	$ 165,480	$ 117,335
Segment income before taxes	5,594	7,060
Assets	891,418		$ 893,137
INF
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	84,426	77,273
BTS
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	43,112	40,062
GEO
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	37,942	0
Operating Segments \| INF
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	85,476	77,772
Segment income before taxes	13,340	12,574
Assets	306,061		303,239
Operating Segments \| BTS
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	43,525	40,274
Segment income before taxes	5,419	5,917
Assets	129,556		131,967
Operating Segments \| GEO
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	37,958	0
Segment income before taxes	7,613	0
Assets	366,933		365,605
Elimination of inter-segment revenues
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	(1,479)	(711)
Segment income before taxes	26,372	18,491
Assets	88,868		$ 92,326
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment income before taxes	$ (20,778)	$ (11,431)

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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