v3.19.1

CONCENTRATION OF CREDIT RISK (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2018 USD ($) markets | Dec. 31, 2017 | Dec. 31, 2016
Concentration Risk [Line Items] |  |  |
FDIC insured amount | $ | $ 250,000 |  |
Number of primary markets (in markets) | markets | 3 |  |
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 0.00% | 0.00% | 0.00%
UNITED STATES | Sales Revenue, Net [Member] | Customers located in the United States |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 95.00% | 88.00% | 97.00%

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