SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands	Mar. 31, 2019 USD ($) subsidary	Jan. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Number of subsidiaries | subsidary	6
Operating lease liability	$ 11,610
Operating lease right of use asset	$ 11,600
Accounting Standards Update 2018-02
Property, Plant and Equipment [Line Items]
Operating lease liability		$ 12,000
Operating lease right of use asset		$ 12,000
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02
Property, Plant and Equipment [Line Items]
Reclassification of certain tax effects from accumulated other comprehensive income			$ 486
Retained Earnings | Accounting Standards Update 2018-02
Property, Plant and Equipment [Line Items]
Reclassification of certain tax effects from accumulated other comprehensive income			$ 486