Business and Significant Accounting Policies - Revenue Remaining Performance Obligation (Details) $ in Millions	Dec. 31, 2018 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, remaining performance obligation	$ 2,700.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, remaining performance obligation	1,620.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, remaining performance obligation	874.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, remaining performance obligation	$ 186.5