FAIR VALUE MEASUREMENTS - Fair value on a nonrecurring basis (Details) - USD ($) $ in Millions |
Jun. 30, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Other Fair Value Measurement Disclosures | ||
| Current maturities of corporate borrowings, carrying value | $ 20.0 | $ 20.0 |
| Corporate borrowings, noncurrent, carrying value | 5,480.4 | $ 5,695.8 |
| Total Carrying Value | ||
| Other Fair Value Measurement Disclosures | ||
| Current maturities of corporate borrowings, carrying value | 20.0 | |
| Corporate borrowings, noncurrent, carrying value | 5,480.4 | |
| Significant other observable inputs (Level 2) | ||
| Other Fair Value Measurement Disclosures | ||
| Current maturities of corporate borrowings, fair value | 18.9 | |
| Corporate borrowings, noncurrent, fair value | 4,446.5 | |
| Significant unobservable inputs (Level 3) | ||
| Other Fair Value Measurement Disclosures | ||
| Corporate borrowings, noncurrent, fair value | $ 761.9 |