SIGNIFICANT ACCOUNTING POLICIES - Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Apr. 01, 2018	Dec. 31, 2017	Sep. 24, 2017	Dec. 31, 2017
Valuation Allowance [Line Items]
Statutory rate (as a percent)	21.00%			35.00%
Measurement period				1 year
Number of years of pre-tax losses		3 years	3 years
Decrease in valuation allowance	$ 14.3
Valuation allowance against majority of deferred tax assets		$ 109.7		$ 109.7
Cumulative impact of establishing valuation allowance	$ (124.0)
Income Tax (benefit) expense
Valuation Allowance [Line Items]
Decrease in valuation allowance		$ 192.3	$ 192.3