Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	Dec. 26, 2021	Dec. 27, 2020
Deferred tax assets:
Stock-based compensation	$ 9.7	$ 7.9
Payroll related accruals	9.2	11.7
Lease accruals	21.8	21.7
Net operating loss carryforwards	58.1	66.0
Tax credit carryforwards	13.1	11.7
Deferred Tax Assets, Tax Deferred Expense	10.8	5.7
Other	16.5	12.8
Gross deferred tax assets	139.2	137.5
Valuation allowance	(9.0)	(7.4)
Total deferred tax assets, net of valuation allowance	130.2	130.1
Deferred tax liabilities:
Unearned revenue	(4.3)	(10.7)
Operating lease right-of-use assets	(19.6)	(19.7)
Other intangibles	(28.0)	(24.6)
Property and equipment, principally due to differences in depreciation	(7.1)	(7.0)
Other	(1.6)	(1.5)
Total deferred tax liabilities	(60.6)	(63.5)
Net deferred tax asset	$ 69.6	$ 66.6