SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Noncontrolling Interests in Consolidated Entities (Details) |
3 Months Ended | 12 Months Ended |
---|---|---|
Mar. 31, 2018 |
Dec. 31, 2015 |
|
Class of Stock [Line Items] | ||
Percentage of carried interest received by general partners (up to) | 1.00% | |
Series A LLC Preferred Stock | ||
Class of Stock [Line Items] | ||
Preferred units dividend rate (as a percent) | 7.375% |