Debt - Debt Acquired in Acquisition (Details) - USD ($) $ in Millions		12 Months Ended
	Sep. 16, 2008	Dec. 31, 2017	Dec. 25, 2016
Debt Instrument [Line Items]
Carrying amount		$ 294.3	$ 432.0
10-year term loan
Debt Instrument [Line Items]
Maturity period (in years)	10 years
Carrying amount		0.8	$ 1.8
Quarterly installment payment - principal		$ 0.3
Basis spread on variable rate (percent)			1.50%