SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCOUNTING STANDARDS UPDATE (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues from contracts with customers		$ 136,773		$ 678,077
Sales tax		6,600		40,900
Accumulated other comprehensive income (loss)		$ (15,212)		(15,212)		$ (12,610)
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings	[1]				$ 2,736
Accounting Standards Update 2017-05
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings	[1]				(4,970)
Deferred gain, unamortized balance					(6,800)
Home Services and Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings					(3,800)
Revenues from contracts with customers			$ 13,100	37,900
Revenues			$ 14,900	$ 33,700
Retained Earnings | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings	[1]				2,736
Retained Earnings | Accounting Standards Update 2017-05
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings	[1]				(4,970)
Retained Earnings | Home Services and Other | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings					(2,700)
Investments in Equity Securities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification to retained earnings	[2]				3,446
Accumulated other comprehensive income (loss)					$ 4,700

[1] See Note 2. Summary of Significant Accounting Policies - Recently Adopted Updates to the Accounting Standards Codification section for more details.

[2] Due to the adoption of ASU No. 2016-01, an amendment to ASC 825, Financial Instruments. See Note 2. Summary of Significant Accounting Policies - Recently Adopted Updates to the Accounting Standards Codification section for more details.