Accounting Policies - Narrative Remaining Performance Obligations (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01	Dec. 31, 2020
One Year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected period of satisfaction	12 months
Expected period of satisfaction, percentage	50.00%
Two Years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected period of satisfaction	24 months
Expected period of satisfaction, percentage	75.00%