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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Credit Risk (Details) - Revenues - Location of facilities	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New York
Concentration of Credit Risk
Percentage of total revenues (as a percent)	16.00%	16.00%	16.00%
Florida
Concentration of Credit Risk
Percentage of total revenues (as a percent)	17.00%	17.00%	18.00%
California
Concentration of Credit Risk
Percentage of total revenues (as a percent)	8.00%	8.00%	8.00%
Texas
Concentration of Credit Risk
Percentage of total revenues (as a percent)	10.00%	10.00%	10.00%

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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.

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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=64851502&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
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-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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-Paragraph 21
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-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611

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