Other Financial Information - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions |
Sep. 30, 2020 |
Dec. 31, 2019 |
Sep. 30, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|---|---|---|---|
| Organization, Consolidation and Presentation of Financial Statements [Abstract] | ||||||
| Cash and cash equivalents | $ 324.3 | $ 223.5 | $ 215.1 | $ 388.0 | ||
| Restricted cash included in other current assets | 8.0 | 10.2 | ||||
| Total cash, cash equivalents, and restricted cash | $ 332.3 | $ 233.7 | $ 159.5 | $ 225.3 | $ 398.2 | $ 249.6 |