SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Rollforward of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions |
3 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2020 |
Mar. 31, 2019 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Accounts Receivable, Allowance for Credit Loss [Roll Forward] | ||||
| Allowance for doubtful accounts, beginning of period | $ 13.4 | $ 12.5 | $ 11.2 | $ 10.9 |
| Current period bad debt expense | 2.5 | 2.0 | ||
| Write-offs, net of recoveries | $ (0.3) | $ (0.4) | ||