Summary of Accounting Policies Summary of Accounting Policies - Effects of Adopting ASC 842 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	$ 76.7	$ 75.3
Other long-term assets	103.6	22.9
Accrued liabilities and other		258.0
Other long-term liabilities	$ 392.4	266.5
Balances Without Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		74.8
Other long-term assets		92.5
Accrued liabilities and other		279.4
Other long-term liabilities		314.2
Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		(0.5)
Other long-term assets		69.6
Accrued liabilities and other		21.4
Other long-term liabilities		$ 47.7