SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Risk and Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Valuation allowance
Deferred tax asset valuation allowance	$ 215,100	$ 161,940
Change in valuation allowance	$ 53,200	$ 37,400
Revenue \| Customer Concentration Risk \| Medicare
Concentration of Credit Risk
Concentration risk (as a percent)	71.00%	80.00%
Accounts Receivable \| Customer Concentration Risk \| Medicare
Concentration of Credit Risk
Concentration risk (as a percent)	64.00%	88.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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-Name Accounting Standards Codification
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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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