INCOME TAXES - Earnings (loss) before income taxes from continuing operations (Details) - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2020 |
Sep. 30, 2019 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Income Tax Disclosure [Abstract] | |||||
| United States | $ (201.1) | $ (351.4) | $ (427.9) | ||
| Non-U.S. | 96.8 | 80.4 | 20.8 | ||
| Income (loss) before income taxes | $ (206.0) | $ (76.0) | $ (104.3) | $ (271.0) | $ (407.1) |