SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated useful lives of assets (Details 2)	12 Months Ended
	Dec. 31, 2018
Building
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	30 years
Building improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Building improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	20 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Computer, office & manufacturing equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Purchased software
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years