Significant Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 26, 2021	Dec. 27, 2020	Dec. 29, 2019
Revenue, Major Customer [Line Items]
Revenue	$ 811.5	$ 747.7	$ 717.5
KGS
Revenue, Major Customer [Line Items]
Revenue	579.6	560.7
U.S. Government | KGS
Revenue, Major Customer [Line Items]
Revenue	$ 571.1	$ 546.4	$ 507.4
U.S. Government | KGS | Revenue Benchmark | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Sales to the U.S. Government, percentage of total revenue (percent)	70.00%	73.00%	71.00%