DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Software, Goodwill and Intangible Assets (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Finite-Lived Intangible Assets [Line Items] | |||
| Goodwill impairment loss | $ 0 | $ 0 | $ 0 |
| Software development costs, capitalized | 0 | 1,800,000 | 5,200,000 |
| Capitalized stock-based compensation expense | $ 0 | $ 300,000 | $ 400,000 |
| 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 | ||