Summary of Significant Accounting Policies - Remaining Performance Obligation (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 $ in Millions |
12 Months Ended |
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Dec. 31, 2018
USD ($)
| |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
Revenue, remaining performance obligation | $ 41.6 |
Revenue, remaining performance obligation, expected timing of satisfaction, period |