PREMISES AND EQUIPMENT, NET - Summary by Country (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total	$ 74,991	$ 45,631
United States
Property, Plant and Equipment [Line Items]
Total	34,817	25,693
India
Property, Plant and Equipment [Line Items]
Total	20,405	3,154
Luxembourg
Property, Plant and Equipment [Line Items]
Total	15,874	14,975
Philippines
Property, Plant and Equipment [Line Items]
Total	3,551	1,754
Other
Property, Plant and Equipment [Line Items]
Total	$ 344	$ 55