Debt (Schedule of Long term debt) (Details) - USD ($) $ in Millions	Dec. 27, 2019	Dec. 28, 2018	Feb. 13, 2018
Current maturities of long-term debt:
Long-term Debt, Current Maturities	$ 634.5	$ 22.7
Debt Issuance Costs, Current, Net	0.9	0.3
Long-term debt:
Long-term Debt, Gross	4,788.3	6,134.0
Debt, Long-term and Short-term, Combined Amount	5,422.8	6,156.7
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	48.0	65.1
Long-term Debt, Including Current Maturities		6,156.7
Long-term Debt [Member]
Long-term debt:
Debt Issuance Costs, Net	47.1	64.8
Senior Notes | 4.75% senior notes due April 2023
Long-term debt:
Long-term Debt, Gross		500.2
Debt Issuance Costs, Net	0.8	3.5
Debt, Long-term and Short-term, Combined Amount	133.7	500.2
Senior Notes | 5.75% senior notes due August 2022
Long-term debt:
Long-term Debt, Gross		835.2
Debt Issuance Costs, Net	3.7	7.0
Debt, Long-term and Short-term, Combined Amount	610.3	835.2
Debentures | Four Point Eight Eight Percent Notes [Member]
Current maturities of long-term debt:
Long-term Debt, Current Maturities	614.8	0.0
Debt Issuance Costs, Current, Net	0.6	0.0
Long-term debt:
Long-term Debt, Gross	0.0	700.0
Debt Issuance Costs, Net	0.0	3.2
Debt, Long-term and Short-term, Combined Amount	614.8	700.0
Debentures | Five Point Six Two Five Percent Note
Long-term debt:
Long-term Debt, Gross		731.4
Debt Issuance Costs, Net	4.4	8.0
Debt, Long-term and Short-term, Combined Amount	514.7	731.4
Debentures | Five Point Five Percent Notes [Member]
Long-term debt:
Long-term Debt, Gross		692.1
Debt Issuance Costs, Net	3.6	7.7
Debt, Long-term and Short-term, Combined Amount	387.2	692.1
Debentures | Ten Point Zero Percent Notes [Member]
Long-term debt:
Long-term Debt, Gross		0.0
Debt Issuance Costs, Noncurrent, Net	9.9	0.0
Debt, Long-term and Short-term, Combined Amount	322.9	0.0
Debentures | 2017 Revolving Credit Facility
Long-term debt:
Long-term Debt, Gross		220.0	$ 900.0
Debt Issuance Costs, Net	3.1	4.5
Debt, Long-term and Short-term, Combined Amount	900.0	220.0
Debentures | Other Loan
Current maturities of long-term debt:
Long-term Debt, Current Maturities	0.0	0.3
Debt Issuance Costs, Current, Net	0.0	0.0
Long-term debt:
Long-term Debt, Gross	0.0	1.9
Debt Issuance Costs, Noncurrent, Net	0.0	0.0
Secured Debt | Receivable securitization, Maturity Date of July 2020 [Member]
Long-term debt:
Long-term Debt, Gross		250.0
Debt Issuance Costs, Net	0.0	0.4
Debt, Long-term and Short-term, Combined Amount	0.0	250.0
Secured Debt | Ten Point Zero Percent Notes [Member]
Long-term debt:
Debt Issuance Costs, Net	10.1
Secured Debt | Term Loan due Sept 2024 [Member]
Current maturities of long-term debt:
Long-term Debt, Current Maturities	15.6	16.4
Debt Issuance Costs, Current, Net	0.2	0.2
Long-term debt:
Long-term Debt, Gross	1,505.2	1,597.4
Debt Issuance Costs, Noncurrent, Net	15.5	19.8
Secured Debt | Term Loan due 2025 [Member]
Current maturities of long-term debt:
Long-term Debt, Current Maturities	4.1	6.0
Debt Issuance Costs, Current, Net	0.1	0.1
Long-term debt:
Long-term Debt, Gross	399.5	591.0
Debt Issuance Costs, Noncurrent, Net	6.1	10.7
Debentures | 8.00% debentures due March 2023
Long-term debt:
Long-term Debt, Gross		4.4
Debt Issuance Costs, Net	0.0	0.0
Debt, Long-term and Short-term, Combined Amount	4.4	4.4
Debentures | 9.50% debentures due May 2022
Long-term debt:
Long-term Debt, Gross		10.4
Debt Issuance Costs, Net	0.0	0.0
Debt, Long-term and Short-term, Combined Amount	$ 10.4	$ 10.4