SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Details About AOCI (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Details about AOCI Components | |||||||||||
| Investment income | $ 6,321 | $ 6,292 | $ 4,917 | $ 3,673 | $ 1,320 | $ 1,334 | $ 683 | $ 595 | $ 21,203 | $ 3,932 | $ 2,018 |
| Reclassification Out Of Accumulated Other Comprehensive Income | |||||||||||
| Details about AOCI Components | |||||||||||
| Investment income | 317 | 55 | 113 | ||||||||
| Accumulated Net Unrealized Investment Gain Loss | Reclassification Out Of Accumulated Other Comprehensive Income | |||||||||||
| Details about AOCI Components | |||||||||||
| Investment income | $ 317 | $ 55 | $ 113 | ||||||||