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Reportable Segments - Summarized Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues	$ 132,598	$ 131,032	$ 127,974	$ 117,335	$ 115,344	$ 104,185	$ 104,018	$ 94,534	$ 508,938	$ 418,081	$ 333,034
Segment income before taxes	5,329	$ 7,403	$ 9,140	$ 7,060	9,806	$ 9,523	$ 8,700	$ 5,690	28,932	33,719	24,633
Assets	893,137				439,421				893,137	439,421
INF
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues									331,161	254,723
BTS
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues									177,777	163,358
Operating Segments \| INF
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues									334,458	257,353	185,238
Segment income before taxes									54,583	43,832	32,245
Assets	776,835				228,979				776,835	228,979
Operating Segments \| BTS
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues									178,419	164,739	152,304
Segment income before taxes									28,138	26,656	21,018
Assets	23,976				155,112				23,976	155,112
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Gross revenues									(3,939)	(4,011)	(4,508)
Segment income before taxes									82,721	70,488	53,263
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment income before taxes									(53,789)	(36,769)	$ (28,630)
Assets	$ 92,326				$ 55,330				$ 92,326	$ 55,330