DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Software, Goodwill and Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment loss			$ 0
Software development costs, capitalized	$ 1,800,000	$ 5,200,000	100,000
Capitalized stock-based compensation expense	$ 300,000	$ 400,000	$ 0
SaaS contract term, one year	1 year
SaaS contract term, three years	3 years
SaaS contract term, five years	5 years
PCS contract term, one year	1 year
PCS contract term, three years	3 years
PCS contract term, five years	5 years
Capitalized Computer Software
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Capitalized Computer Software | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Capitalized Computer Software | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years