SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Property, plant and equipment other than software development and conversion cost | Minimum
Property and Equipment
Estimated useful life	1 year
Property, plant and equipment other than software development and conversion cost | Maximum
Property and Equipment
Estimated useful life	21 years
Software Development and Conversion Costs | Minimum
Property and Equipment
Estimated useful life	1 year
Software Development and Conversion Costs | Maximum
Property and Equipment
Estimated useful life	7 years