BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Impact on Statement of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1],[2],[3],[4],[5],[6],[7]	Sep. 30, 2018	[1],[2],[3],[4],[5],[6],[7]	Jun. 30, 2018	[1],[2],[3],[4],[5],[6],[7]	Mar. 31, 2018	[1],[2],[3],[4],[5],[6],[7]	Dec. 31, 2017	[7],[8]	Sep. 30, 2017	[7],[8]	Jun. 30, 2017	[7],[8]	Mar. 31, 2017	[7],[8]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 217,633		$ 204,575		$ 218,556		$ 197,438		$ 216,066		$ 234,979		$ 250,685		$ 240,483		$ 838,202	$ 942,213	$ 997,303
Cost of revenue																	622,165	699,865	690,045
Gross profit	53,448		56,995		55,350		50,244		54,445		60,081		65,292		62,530		216,037	242,348	307,258
Income from operations																	42,495	49,706	65,103
Income (loss) before income taxes and non-controlling interests	(12,829)		16,129		3,071		(4,972)		3,112		10,357		12,160		9,746		1,399	35,375	44,321
Income tax (provision) benefit																	(4,098)	276,256	(12,935)
Net (loss) income	(10,868)		9,521		2,255		(3,607)		286,983		7,766		9,722		7,160		(2,699)	311,631	31,386
Net (loss) income attributable to Altisource	$ (11,485)		$ 8,667		$ 1,568		$ (4,132)		$ 286,350		$ 6,961		$ 9,035		$ 6,545		(5,382)	$ 308,891	$ 28,693
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue																	(6,692)
Cost of revenue																	2,116
Gross profit																	(8,808)
Income from operations																	(8,808)
Income (loss) before income taxes and non-controlling interests																	(8,808)
Income tax (provision) benefit																	2,637
Net (loss) income																	(6,171)
Net (loss) income attributable to Altisource																	(6,171)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue																	831,510
Cost of revenue																	624,281
Gross profit																	207,229
Income from operations																	33,687
Income (loss) before income taxes and non-controlling interests																	(7,409)
Income tax (provision) benefit																	(1,461)
Net (loss) income																	(8,870)
Net (loss) income attributable to Altisource																	$ (11,553)

[1] Effective January 1, 2018, the Company adopted Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which requires certain equity investments to be measured at fair value with changes in fair value recognized in net income. Previously, changes in the fair value of the Company’s available for sale securities were included in comprehensive income. During the three months ended March 31, 2018, June 30, 2018, September 30, 2018 and December 31, 2018, we recognized unrealized (losses) gains from our investment in RESI common shares of $(7.5) million, $1.5 million, $1.8 million and $(8.8) million, respectively. See Note 6.

[2] In April 2018, Altisource entered into the Credit Agreement, pursuant to which, among other things, Altisource borrowed $412.0 million in the form of Term B Loans. Proceeds from the Term B Loans were used to repay the Company’s prior senior secured term loan. In connection with the refinancing, we recognized a loss of $4.4 million from the write-off of the unamortized debt issuance costs and debt discount in the second quarter of 2018. See Note 14.

[3] In August 2018, we initiated Project Catalyst, a restructuring plan intended to optimize our operations and reduce costs to align our cost structure with our anticipated revenues and improve our operating margins. During the three months ended September 30, 2018 and December 31, 2018, we incurred $3.4 million and $8.1 million, respectively, of severance costs, facility shut-down costs and professional services fees related to the restructuring plan. See Note 24.

[4] In August 2018, we sold our rental property management business to RESI for total transaction proceeds of $18.0 million, $15.0 million of which was received on the closing date of August 8, 2018 and $3.0 million of which will be received on the earlier of a RESI change of control or August 8, 2023. We recognized a $13.7 million pretax gain on the sale of this business during the third quarter of 2018. See Note 4.

[5] In November 2018, the Company announced its plans to sell its BRS Inventory and discontinue the Company’s BRS business. The Company recorded a write-off of goodwill related to its plan to discontinue the BRS business of $2.6 million during the three months ended December 31, 2018. See Notes 9 and 11.

[6] In connection with a United States Supreme Court decision in June 2018, the Company is analyzing its services for potential exposure to sales tax in various jurisdictions in the United States and believes that the Company has a related estimated probable loss of $6.2 million. The Company recognized $5.9 million and $0.4 million during the three months ended September 30, 2018 and December 31, 2018, respectively. See Note 25.

[7] The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and changes in the number of weighted average shares outstanding for each period.

[8] During the three months ended December, 31, 2017, the Company recognized net tax benefits of $284.1 million. On December 27, 2017, two of the Company’s wholly-owned subsidiaries, Altisource Solutions S.à r.l. and Altisource Holdings S.à r.l., merged, with Altisource Holdings S.à r.l. as the surviving entity. For Luxembourg tax purposes, the merger was recognized at fair value and generated an NOL of $1.3 billion and a deferred tax asset, net of valuation allowance, of $300.9 million. This deferred tax benefit was partially offset by $6.3 million of income tax from changes in U.S. and Luxembourg income tax rates and a $10.5 million increase in certain foreign income tax reserves (and related interest). See Note 22.