Match (MTCH) 10-K 1 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 01, 2019	Jun. 30, 2018
Document Information [Line Items]
Entity Registrant Name	IAC/INTERACTIVECORP
Entity Central Index Key	891,103
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 11,833,394,558
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		77,986,305
Class B Convertible Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,789,499

CONSOLIDATED BALANCE SHEET

CONSOLIDATED BALANCE SHEET - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 2,131,632	$ 1,630,809
Marketable securities	123,665	4,995
Accounts receivable, net of allowance and reserves of $18,860 and $11,489, respectively	279,189	304,027
Other current assets	228,253	185,374
Total current assets	2,762,739	2,125,205
Property and equipment, net of accumulated depreciation and amortization	318,800	315,170
Goodwill	2,726,859	2,559,066
Intangible assets, net of accumulated amortization	631,422	663,737
Long-term investments	235,055	64,977
Deferred income taxes	64,786	66,321
Other non-current assets	134,924	73,334
TOTAL ASSETS	6,874,585	5,867,810
LIABILITIES:
Current portion of long-term debt	13,750	13,750
Accounts payable, trade	74,907	76,571
Deferred revenue	360,015	342,483
Accrued expenses and other current liabilities	434,886	366,924
Total current liabilities	883,558	799,728
Long-term debt, net	2,245,548	1,979,469
Income taxes payable	37,584	25,624
Deferred income taxes	23,600	35,070
Other long-term liabilities	66,807	38,229
Redeemable noncontrolling interests	65,687	42,867
Commitments and contingencies
SHAREHOLDERS' EQUITY:
Additional paid-in capital	12,022,387	12,165,002
Retained earnings	1,258,794	595,038
Accumulated other comprehensive loss	(128,722)	(103,568)
Treasury stock 194,708 and 194,163 shares, respectively	(10,309,612)	(10,226,721)
Total IAC shareholders' equity	2,843,125	2,430,028
Noncontrolling interests	708,676	516,795
Total shareholders' equity	3,551,801	2,946,823
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	6,874,585	5,867,810
Common stock $.001 par value; authorized 1,600,000 shares; issued 262,303 and 260,624 shares, respectively, and outstanding 77,963 and 76,829 shares, respectively
SHAREHOLDERS' EQUITY:
Common stock	262	261
Class B convertible common stock $.001 par value; authorized 400,000 shares; issued 16,157 shares and outstanding 5,789 shares
SHAREHOLDERS' EQUITY:
Common stock	$ 16	$ 16

CONSOLIDATED BALANCE SHEET (Par

CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Allowance and reserves of accounts receivable	$ 18,860	$ 11,489
Treasury stock (shares)	194,708,000	194,163,000
Common Stock
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	1,600,000,000	1,600,000,000
Common stock issued (shares)	262,303,000	260,624,000
Common stock outstanding (shares)	77,963,000	76,829,000
Class B Convertible Common Stock
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	400,000,000	400,000,000
Common stock issued (shares)	16,157,000	16,157,000
Common stock outstanding (shares)	5,789,000	5,789,000

CONSOLIDATED STATEMENT OF OPERA

CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	253,722	237,238	218,224	201,962	199,727	166,290	139,033	145,958	911,146	651,008	755,730
Selling and marketing expense									1,519,440	1,381,221	1,247,097
General and administrative expense									774,079	719,257	530,446
Product development expense									309,329	250,879	212,765
Depreciation									75,360	74,265	71,676
Amortization of intangibles									108,399	42,143	79,426
Goodwill impairment									0	0	275,367
Total operating costs and expenses									3,697,753	3,118,773	3,172,507
Operating income (loss)	133,920	172,832	168,437	89,950	94,360	(18,589)	75,635	37,060	565,139	188,466	(32,625)
Interest expense									(109,327)	(105,295)	(109,110)
Other income (expense), net									305,746	(16,213)	60,650
Earnings (loss) before income taxes									761,558	66,958	(81,085)
Income tax (provision) benefit						(257,000)			(3,811)	291,050	64,934
Net earnings (loss)	217,477	171,577	280,854	87,839	23,349	225,639	80,557	28,463	757,747	358,008	(16,151)
Net earnings attributable to noncontrolling interests									(130,786)	(53,084)	(25,129)
Net earnings (loss) attributable to IAC shareholders	$ 191,752	$ 145,774	$ 218,353	$ 71,082	$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 626,961	$ 304,924	$ (41,280)
Per share information attributable to IAC shareholders:
Basic earnings (loss) per share (USD per share)	$ 2.29	$ 1.75	$ 2.61	$ 0.86	$ 0.40	$ 2.22	$ 0.84	$ 0.34	$ 7.52	$ 3.81	$ (0.52)
Diluted earnings (loss) per share (USD per share)	$ 2.04	$ 1.49	$ 2.32	$ 0.71	$ 0.37	$ 1.79	$ 0.70	$ 0.29	$ 6.59	$ 3.18	$ (0.52)
Stock-based compensation expense by function:
Stock-based compensation expense									$ 238,420	$ 264,618	$ 104,820
Cost of revenue
Stock-based compensation expense by function:
Stock-based compensation expense									2,482	1,881	2,305
Selling and marketing expense
Stock-based compensation expense by function:
Stock-based compensation expense									7,943	31,318	6,000
General and administrative expense
Stock-based compensation expense by function:
Stock-based compensation expense									188,510	192,957	77,151
Product development expense
Stock-based compensation expense by function:
Stock-based compensation expense									$ 39,485	$ 38,462	$ 19,364

CONSOLIDATED STATEMENT OF COMPR

CONSOLIDATED STATEMENT OF COMPREHENSIVE OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 757,747	$ 358,008	$ (16,151)
Other comprehensive (loss) income, net of tax:
Change in foreign currency translation adjustment	(31,411)	80,269	(43,126)
Change in unrealized gains and losses on available-for-sale securities (net of tax benefit of $3,846 and $884 in 2017 and 2016, respectively)	5	(4,026)	1,484
Total other comprehensive (loss) income	(31,406)	76,243	(41,642)
Comprehensive income (loss), net of tax	726,341	434,251	(57,793)
Components of comprehensive (income) loss attributable to noncontrolling interests:
Net earnings attributable to noncontrolling interests	(130,786)	(53,084)	(25,129)
Change in foreign currency translation adjustment attributable to noncontrolling interests	6,129	(13,797)	6,033
Change in unrealized gain and losses of available-for-sale securities attributable to noncontrolling interests	(1)	0	458
Comprehensive income attributable to noncontrolling interests	(124,658)	(66,881)	(18,638)
Comprehensive income (loss) attributable to IAC shareholders	$ 601,683	$ 367,370	$ (76,431)

CONSOLIDATED STATEMENT OF COM_2

CONSOLIDATED STATEMENT OF COMPREHENSIVE OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Change in unrealized gains and losses on available-for-sale securities, tax provision (benefit)	$ 0	$ (3,846)	$ (884)

CONSOLIDATED STATEMENT OF SHARE

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Total IAC Shareholders' Equity	Redeemable Noncontrolling Interests	Common StockCommon Stock	Common StockClass B Convertible Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock	Noncontrolling Interests	Match Group	Match GroupTotal IAC Shareholders' Equity	Match GroupAdditional Paid-in Capital	Match GroupAccumulated Other Comprehensive (Loss) Income	Match GroupNoncontrolling Interests	ANGI Homeservices	ANGI HomeservicesTotal IAC Shareholders' Equity	ANGI HomeservicesAdditional Paid-in Capital	ANGI HomeservicesAccumulated Other Comprehensive (Loss) Income	ANGI HomeservicesNoncontrolling Interests
Balance at beginning of period at Dec. 31, 2015				$ 30,391
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) earnings				(3,849)
Other comprehensive income (loss), net of tax				385
Stock-based compensation expense				1,632
Purchase of redeemable noncontrolling interests				(2,529)
Adjustment of redeemable noncontrolling interests to fair value				7,921
Noncontrolling interests created in acquisitions	$ 22,033		$ 12,222				$ 12,222				$ 9,811
Other				(1,124)
Balance at end of period at Dec. 31, 2016				32,827
Balance at beginning of period at Dec. 31, 2015	2,215,825		1,804,526		$ 254	$ 16	11,486,315	$ 331,394	$ (152,103)	$ (9,861,350)	411,299
Balance at beginning of period (shares) at Dec. 31, 2015					254,015,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings	(12,302)		(41,280)					(41,280)			28,978
Other comprehensive income (loss), net of tax	(42,027)		(35,151)						(35,151)		(6,876)
Stock-based compensation expense	94,724		50,201				50,201				44,523
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(770)		(770)		$ 2		(772)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)					1,657,000
Income tax benefit related to stock-based awards	49,406		49,406				49,406
Purchase of treasury stock	(315,250)	$ (315,300)	(315,250)							(315,250)
Adjustment of redeemable noncontrolling interests to fair value	(7,560)		(7,560)				(7,560)
Purchase of noncontrolling interests	(211)										(211)
Issuance of Match Group common stock pursuant to stock-based awards, net of withholding taxes	10,224										10,224
Reallocation of shareholders' equity balances related to the noncontrolling interests created in the Match Group IPO	0		363,638				342,507		21,131		(363,638)
Changes in noncontrolling interests of Match Group due to the issuance of its common stock	0		(7,691)				(7,691)				7,691
Noncontrolling interests created in an acquisition	22,033		12,222				12,222				9,811
Other	(3,422)		(3,069)				(3,069)				(353)
Balance at end of period at Dec. 31, 2016	2,010,670		1,869,222		$ 256	$ 16	11,921,559	290,114	(166,123)	(10,176,600)	141,448
Balance at end of period (shares) at Dec. 31, 2016					255,672,000	16,157,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) earnings				3,620
Other comprehensive income (loss), net of tax				1,291
Stock-based compensation expense				2,017
Purchase of redeemable noncontrolling interests				(14,641)
Adjustment of redeemable noncontrolling interests to fair value				6,341
Noncontrolling interests created in acquisitions				17,758
Other				(6,346)
Balance at end of period at Dec. 31, 2017	42,867			42,867
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings	354,388		304,924					304,924			49,464
Other comprehensive income (loss), net of tax	74,952		62,446						62,446		12,506
Stock-based compensation expense	246,388		66,333				66,333				180,055
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(10,504)		(10,504)		$ 5		(10,509)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)					4,952,000
Purchase of treasury stock	(50,121)	(50,100)	(50,121)							(50,121)
Adjustment of redeemable noncontrolling interests to fair value	(6,341)		(6,341)				(6,341)
Purchase of noncontrolling interests	(848)										(848)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests												$ (464,209)	$ (460,774)	$ (460,890)	$ 116	$ (3,435)	$ (8,493)	$ (11,223)	$ (11,216)	$ (7)	$ 2,730
Purchase of exchangeable note hedge	(74,365)		(74,365)				(74,365)
Equity component of exchangeable debt issuance, net of deferred financing costs and deferred tax asset	71,158		71,158				71,158
Acquisition of Angie's List and creation of noncontrolling interests in ANGI Homeservices	779,471		645,475				645,475				133,996
Noncontrolling interests created in an acquisition				17,758
Issuance of warrants	23,650		23,650				23,650
Other	1,027		148				148				879
Balance at end of period at Dec. 31, 2017	2,946,823		2,430,028		$ 261	$ 16	12,165,002	595,038	(103,568)	(10,226,721)	516,795
Balance at end of period (shares) at Dec. 31, 2017					260,624,000	16,157,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) earnings				33,897
Other comprehensive income (loss), net of tax				(702)
Stock-based compensation expense				1,138
Purchase of redeemable noncontrolling interests				(8,350)
Adjustment of redeemable noncontrolling interests to fair value				4,098
Noncontrolling interests created in acquisitions	14,307			2,261							14,307
Other				(9,522)
Balance at end of period at Dec. 31, 2018	65,687			65,687
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings	723,850		626,961					626,961			96,889
Other comprehensive income (loss), net of tax	(30,704)		(25,278)						(25,278)		(5,426)
Stock-based compensation expense	237,282		75,311				75,311				161,971
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	21,786		21,786		$ 1		21,785
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)					1,679,000
Purchase of treasury stock	(82,891)	$ (82,900)	(82,891)							(82,891)
Adjustment of redeemable noncontrolling interests to fair value	(4,098)		(4,098)				(4,098)
Purchase of noncontrolling interests	(9,364)										(9,364)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests												$ (341,400)	$ (342,457)	$ (342,592)	$ 135	$ 1,057	140,706	$ 106,204	$ 106,215	$ (11)	34,502
Dividends paid to Match Group noncontrolling interests																	$ (105,126)				$ (105,126)
Noncontrolling interests created in an acquisition	14,307			$ 2,261							14,307
Other	425		764				764				(339)
Balance at end of period at Dec. 31, 2018	$ 3,551,801		$ 2,843,125		$ 262	$ 16	$ 12,022,387	$ 1,258,794	$ (128,722)	$ (10,309,612)	$ 708,676
Balance at end of period (shares) at Dec. 31, 2018					262,303,000	16,157,000

CONSOLIDATED STATEMENT OF SHA_2

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Class B Convertible Common Stock
Common stock, par value (USD per share)	0.001	0.001
Common Stock | Common Stock
Common stock, par value (USD per share)	1	1	$ 1
Common Stock | Class B Convertible Common Stock
Common stock, par value (USD per share)	$ 1	$ 1	$ 1

CONSOLIDATED STATEMENT OF CASH

CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net earnings (loss)	$ 757,747	$ 358,008	$ (16,151)
Adjustments to reconcile net earnings (loss) to net cash provided by operating activities:
Stock-based compensation expense	238,420	264,618	104,820
Amortization of intangibles	108,399	42,143	79,426
Depreciation	75,360	74,265	71,676
Bad debt expense	48,445	28,930	17,733
Goodwill impairment	0	0	275,367
Deferred income taxes	(34,679)	(285,278)	(119,181)
Unrealized gains on equity securities, net	(124,170)	0	0
Gains from the sale of businesses and investments, net	(147,829)	(32,673)	(50,965)
Other adjustments, net	15,763	61,647	596
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Accounts receivable	(34,828)	(115,169)	1,283
Other assets	(44,557)	5,688	(12,808)
Accounts payable and other liabilities	53,555	(25,289)	(52,359)
Income taxes payable and receivable	27,034	655	8,998
Deferred revenue	49,468	39,154	35,803
Net cash provided by operating activities	988,128	416,699	344,238
Cash flows from investing activities:
Acquisitions, net of cash acquired	(64,496)	(146,553)	(18,403)
Capital expenditures	(85,634)	(75,523)	(78,039)
Proceeds from maturities and sales of marketable debt securities	333,600	114,350	252,369
Purchases of marketable debt securities	(449,676)	(29,891)	(313,943)
Investments in time deposits	0	0	(87,500)
Proceeds from maturities of time deposits	0	0	87,500
Net proceeds from the sale of businesses and investments	136,719	185,778	172,228
Purchases of investments	(52,980)	(9,106)	(12,565)
Other, net	9,027	2,994	11,215
Net cash (used in) provided by investing activities	(173,440)	42,049	12,862
Cash flows from financing activities:
Purchase of exchangeable note hedge	0	(74,365)	0
Proceeds from issuance of warrants	0	23,650	0
Debt issuance costs	(5,449)	(33,744)	(7,811)
Dividends paid to Match Group noncontrolling interests	(105,126)	0	0
Purchase of noncontrolling interests	(16,063)	(15,439)	(2,740)
Acquisition-related contingent consideration payments	(185)	(27,289)	(2,180)
Other, net	(5,375)	(5,000)	(2,705)
Net cash used in financing activities	(312,798)	(196,869)	(492,140)
Total cash provided (used)	501,890	261,879	(135,040)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(1,887)	11,604	(6,434)
Net increase (decrease) in cash, cash equivalents, and restricted cash	500,003	273,483	(141,474)
Cash, cash equivalents, and restricted cash at beginning of period	1,633,682	1,360,199	1,501,673
Cash, cash equivalents, and restricted cash at end of period	2,133,685	1,633,682	1,360,199
IAC/InterActiveCorp
Cash flows from financing activities:
Proceeds from issuance of debt	0	517,500	0
Repurchases of IAC debt	(363)	(393,464)	(126,409)
Purchase of treasury stock	(82,891)	(56,424)	(308,948)
Proceeds from the exercise of stock options	41,700	82,397	25,821
Withholding taxes paid on behalf of employees on net settled stock-based awards	(18,982)	(93,832)	(26,716)
Match Group and ANGI Homeservices
Cash flows from financing activities:
Proceeds from the exercise of stock options	4,705	61,095	39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards	(237,564)	(264,323)	(29,830)
Match Group
Cash flows from financing activities:
Proceeds from issuance of debt	260,000	525,000	400,000
Principal payments on debt	0	(445,172)	(450,000)
Purchase of treasury stock	(133,455)	0	0
Proceeds from the exercise of stock options			39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards			(29,830)
Purchase of Match Group stock-based awards	0	(272,459)	0
ANGI Homeservices
Cash flows from financing activities:
Principal payments on debt	$ (13,750)	0	$ 0
Borrowing under ANGI Homeservices Term Loan		$ 275,000

ORGANIZATION

ORGANIZATION	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	ORGANIZATION IAC has majority ownership of both Match Group, which includes Tinder, Match, PlentyOfFish and OkCupid, and ANGI Homeservices, which includes HomeAdvisor, Angie’s List and Handy, and also operates Vimeo, Dotdash and The Daily Beast, among many other online businesses. As used herein, "IAC," the "Company," "we," "our" or "us" and similar terms refer to IAC/InterActiveCorp and its subsidiaries (unless the context requires otherwise). During the fourth quarter of 2018, the Company realigned its reportable segments as follows: • the Match Group, ANGI Homeservices and Applications segments remain unchanged; • Vimeo is now reported as its own segment (it was previously included in the Video segment, which has been eliminated); • Dotdash is now reported as its own segment (it was previously included in the Publishing segment, which has been eliminated); and • the Company's Other segment has been renamed, Emerging & Other, and the businesses previously included in the Video segment (other than Vimeo) and the Publishing segment (other than Dotdash) are now included in the Emerging & Other segment. Match Group Our Match Group segment consists of the businesses and operations of Match Group, Inc. ("Match Group" or "MTCH"). MTCH completed its initial public offering ("IPO") on November 24, 2015. At December 31, 2018 , IAC’s economic and voting interest in MTCH were 81.1% and 97.6% , respectively. MTCH is a leading provider of dating products available in over 40 languages to our users all over the world through applications and websites that we own and operate. MTCH operates a portfolio of dating brands, including Tinder, Match, PlentyOfFish, Meetic, OkCupid, OurTime, Pairs and Hinge, as well as a number of other brands, each designed to increase users likelihood of finding a meaningful connection. Through our portfolio of trusted brands, we provide tailored products to meet the varying preferences of our users. ANGI Homeservices Our ANGI Homeservices segment includes the North American (United States and Canada) and European businesses and operations of ANGI Homeservices Inc. ("ANGI"). On September 29, 2017, the Company's HomeAdvisor business and Angie's List Inc. ("Angie's List") combined under a new publicly traded company called ANGI Homeservices Inc. (the "Combination"). At December 31, 2018 , IAC’s economic and voting interest in ANGI were 83.9% and 98.1% , respectively. ANGI connects millions of homeowners to home service professionals through its portfolio of digital home service brands, including HomeAdvisor®, Angie’s List® and Handy Technologies, Inc. ("Handy"). Combined, these leading marketplaces have collected more than 15 million reviews over the course of 20 years, allowing homeowners to research, match and connect on-demand to the largest network of service professionals online, through our mobile apps or by voice assistants. On October 19, 2018, ANGI acquired Handy, a leading platform in the United States for connecting people looking for household services (primarily cleaning and handyman services) with top-quality, pre-screened independent service professionals. ANGI also owns and operates mHelpDesk, a provider of cloud-based field service software for small to mid-size businesses, primarily sold today to HomeAdvisor service professionals, and CraftJack. Prior to its sale on December 31, 2018, ANGI also operated Felix, a pay-per-call advertising service business. In addition to its market-leading U.S. operations, ANGI owns leading home services online marketplaces in France (Travaux), Germany (MyHammer), Netherlands (Werkspot), United Kingdom (MyBuilder Limited or "MyBuilder," acquired a controlling interest on March 24, 2017), Canada (HomeStars Inc. or "HomeStars," acquired a controlling interest on February 8, 2017) and Italy (Instapro), as well as operations in Austria (MyHammer). Vimeo Vimeo operates a global video platform for creative professionals, marketers and enterprises to connect with their audiences, customers and employees. Vimeo provides cloud-based software products to stream, host, distribute and monetize videos online and across devices, as well as premium video tools on a subscription basis. Vimeo also sells live streaming accessories. Dotdash Dotdash is a portfolio of digital brands providing expert information and inspiration in select vertical content categories. Applications Our Applications segment consists of our Desktop business and Mosaic Group (previously referred to as Mobile), our mobile business. Through these businesses, we are a leading provider of global, advertising-driven desktop and subscription-based mobile applications. Through our Desktop business, we own and operate a portfolio of desktop browser applications that provide users with access to a wide variety of online content, tools and services. We provide users who download our desktop browser applications with new tab search services, as well as the option of default browser search services. We distribute our desktop browser applications to consumers free of charge on an opt-in basis directly through direct to consumer (primarily Chrome Web Store) and partnership distribution channels. Through Mosaic Group, we are a leading provider of global subscription mobile applications. Mosaic Group consists of the following businesses that we own and operate: Apalon, iTranslate, acquired in March 2018, TelTech, acquired in October 2018, and Daily Burn, transferred from the Emerging & Other segment effective April 1, 2018. Apalon is a leading mobile development company with one of the largest and most popular application portfolios worldwide. iTranslate develops and distributes applications that enable users to read, write, speak and learn foreign languages anywhere in the world. TelTech develops and distributes unique and innovative mobile communications applications that help protect consumer privacy. Daily Burn is a health and fitness property that provides streaming fitness and workout videos across a variety of platforms (including iOS, Android, Roku and other Internet-enabled television platforms). Emerging & Other Our Emerging & Other segment primarily includes: • Ask Media Group, a collection of websites providing general search services and information; • BlueCrew, an on-demand staffing platform that connects temporary workers with traditional blue-collar jobs in areas like warehouse, delivery and moving, data entry and customer service; • The Daily Beast, a website dedicated to news, commentary, culture and entertainment that publishes original reporting and opinion from its roster of full-time journalists and contributors; • College Humor Media, a provider of digital content, including its recently launched subscription only property, Dropout.tv; and • IAC Films, a provider of production and producer services for feature films, primarily for initial sale and distribution through theatrical releases and video-on-demand services in the United States and internationally. • For periods prior to their sales: ◦ CityGrid, an advertising network that integrated local content and advertising for distribution to affiliated and third-party publishers across web and mobile platforms, sold December 31, 2018. ◦ Dictionary.com, an online and mobile dictionary and thesaurus service, sold November 13, 2018. ◦ Electus, including Notional, a provider of production and producer services for both unscripted and scripted television and digital content, primarily for initial sale and distribution in the United States, sold October 29, 2018. ◦ The Princeton Review, a provider of educational test preparation, academic tutoring and college counseling services, sold on March 31, 2017. ◦ ShoeBuy, an Internet retailer of footwear and related apparel and accessories, sold December 30, 2016. ◦ ASKfm, a questions and answers social network, sold June 30, 2016. ◦ PriceRunner, a shopping comparison website, sold March 18, 2016.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Consolidation The Company prepares its consolidated financial statements in accordance with U.S. generally accepted accounting principles ("GAAP"). The consolidated financial statements include the accounts of the Company, all entities that are wholly-owned by the Company and all entities in which the Company has a controlling financial interest. Intercompany transactions and accounts have been eliminated. Accounting for Investments and Equity Securities Investments in the common stock or in-substance common stock of entities in which the Company has the ability to exercise significant influence over the operating and financial matters of the investee, but does not have a controlling financial interest, are accounted for using the equity method and are included in "Long-term investments" in the accompanying consolidated balance sheet. At December 31, 2018, the Company did not have any investments accounted for using the equity method. Investments in equity securities, other than those of our consolidated subsidiaries and those accounted for under the equity method, are accounted for at fair value or under the measurement alternative of Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , following its adoption on January 1, 2018, with any changes to fair value recognized within other income (expense), net each reporting period. Under the measurement alternative, equity investments without readily determinable fair values are carried at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer; value is generally determined based on a market approach as of the transaction date. An investment will be considered identical or similar if it has identical or similar rights to the equity investments held by the Company. The Company reviews its equity securities for impairment each reporting period when there are qualitative factors or events that indicate possible impairment. Factors we consider in making this determination include negative changes in industry and market conditions, financial performance, business prospects, and other relevant events and factors. When indicators of impairment exist, the Company prepares quantitative assessments of the fair value of our equity securities, which require judgment and the use of estimates. When our assessment indicates that the fair value of the security is below the carrying value, the Company writes down the security to its fair value and records the corresponding charge within other income (expense), net. See " Accounting Pronouncements adopted by the Company" below for further information. Accounting Estimates Management of the Company is required to make certain estimates, judgments and assumptions during the preparation of its consolidated financial statements in accordance with GAAP. These estimates, judgments and assumptions impact the reported amounts of assets, liabilities, revenue and expenses and the related disclosure of contingent assets and liabilities. Actual results could differ from these estimates. On an ongoing basis, the Company evaluates its estimates and judgments, including those related to: the recoverability of goodwill and indefinite-lived intangible assets; the useful lives and recoverability of definite-lived intangible assets and property and equipment; the fair values of marketable debt securities and equity securities without readily determinable fair values; the carrying value of accounts receivable, including the determination of the allowance for doubtful accounts; the determination of revenue reserves; the fair value of acquisition-related contingent consideration arrangements; unrecognized tax benefits; the valuation allowance for deferred income tax assets; and the fair value of and forfeiture rates for stock-based awards, among others. The Company bases its estimates and judgments on historical experience, its forecasts and budgets and other factors that the Company considers relevant. Revenue Recognition The Company adopted the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, effective January 1, 2018 using the modified retrospective transition method for open contracts as of the date of initial application. See " Accounting Pronouncements adopted by the Company" below for further information. The Company accounts for a contract with a customer when it has approval and commitment from all parties, the rights of the parties and payment terms are identified, the contract has commercial substance and collectability of consideration is probable. Revenue is recognized when control of the promised services or goods is transferred to our customers, and in an amount that reflects the consideration the Company is contractually due in exchange for those services or goods. Transaction Price The objective of determining the transaction price is to estimate the amount of consideration the Company is due in exchange for its services or goods, including amounts that are variable. The Company determines the total transaction price, including an estimate of any variable consideration, at contract inception and reassesses this estimate each reporting period. The Company excludes from the measurement of transaction price all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of revenue or cost of revenue. For contracts that have an original duration of one year or less, the Company uses the practical expedient available under ASU No. 2014-09 applicable to such contracts and does not consider the time value of money. Arrangements with Multiple Performance Obligations The Company’s contracts with customers may include multiple performance obligations. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The Company generally determines standalone selling prices based on the prices charged to customers, which are directly observable or based on an estimate if not directly observable. For our multiple performance obligation arrangements that include functional intellectual property ("IP"), which comprise the downloadable apps and software of the Applications segment, the Company uses a residual approach to determine standalone selling prices for the functional IP. Assets Recognized from the Costs to Obtain a Contract with a Customer The Company has determined that certain costs, primarily commissions paid to employees pursuant to certain sales incentive programs and mobile app store fees, meet the requirements to be capitalized as a cost of obtaining a contract. Commissions paid to employees pursuant to certain sales incentive programs are amortized over the estimated customer relationship period. The Company calculates the estimated customer relationship period as the average customer life, which is based on historical data. When customer renewals are expected and the renewal commission is not commensurate with the initial commission, the average customer life includes renewal periods. For sales incentive programs where the customer relationship period is one year or less, the Company has elected the practical expedient to expense the costs as incurred. The Company generally capitalizes and amortizes mobile app store fees over the term of the applicable subscription. During the year ended December 31, 2018, the Company recognized expense of $355.3 million related to the amortization of these costs. The current and non-current contract asset balances at December 31, 2018 are $69.8 million and $4.5 million , respectively. The current and non-current contract assets are included in "Other current assets" and "Other non-current assets," respectively, in the accompanying consolidated balance sheet. Performance Obligations As permitted under the practical expedient available under ASU No. 2014-09, the Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less, (ii) contracts with variable consideration that is allocated entirely to unsatisfied performance obligations or to a wholly unsatisfied promise accounted for under the series guidance, and (iii) contracts for which the Company recognizes revenue at the amount which we have the right to invoice for services performed. Match Group Match Group revenue is primarily derived directly from users in the form of recurring subscriptions. Subscription revenue is presented net of credits and credit card chargebacks. Subscribers pay in advance, primarily by credit card or through mobile app stores, and, subject to certain conditions identified in our terms and conditions, generally all purchases are final and nonrefundable. Revenue is initially deferred and is recognized using the straight-line method over the term of the applicable subscription period, which generally ranges from one to six months . Revenue is also earned from online advertising, the purchase of à la carte features and offline events. Online advertising revenue is recognized when an advertisement is displayed. Revenue from the purchase of à la carte features is recognized based on usage. Revenue associated with offline events is recognized when each event occurs. ANGI Homeservices ANGI revenue is primarily derived from (i) consumer connection revenue, which comprises fees paid by HomeAdvisor service professionals for consumer matches (regardless of whether the service professional ultimately provides the requested service) and booking fees from completed jobs sourced through the Handy platform, and (ii) membership subscription fees paid by HomeAdvisor service professionals. Consumer connection revenue varies based upon several factors, including the service requested, product experience offered and geographic location of service. The Company’s consumer connection revenue is generated and recognized when an in-network service professional is delivered a consumer match or when a job sourced through the Handy platform is completed. Membership subscription revenue from service professionals is initially deferred and is recognized using the straight-line method over the applicable subscription period, which is typically one year . Consumer connection revenue is generally billed one week following a consumer match, with payment due upon receipt of invoice or collected when a consumer schedules a job through the Handy platform. The Company maintains revenue reserves for potential credits for services provided by Handy service professionals to consumers. ANGI revenue is also derived from Angie's List (i) sales of time-based website, mobile and call center advertising to service professionals and (ii) membership subscription fees from consumers. Angie's List service professionals generally pay for advertisements in advance on a monthly or annual basis at the option of the service professional, with the average advertising contract term being approximately one year. Angie's List website, mobile and call center advertising revenue is recognized ratably over the contract term. Revenue from the sale of advertising in the Angie’s List Magazine is recognized in the period in which the publication is distributed. Angie's List prepaid consumer membership subscription fees are recognized as revenue using the straight-line method over the term of the applicable subscription period, which is typically one year . Vimeo Vimeo revenue is derived primarily from annual and monthly SaaS subscription fees paid by creators for premium capabilities and, to a lesser extent, sales of live streaming hardware, software and professional services. Subscription revenue is recognized over the terms of the applicable subscription period, which are typically one month or one year . Dotdash Dotdash revenue consists principally of digital advertising revenue and affiliate commerce commission revenue. Digital advertising revenue is generated primarily through digital display advertisements sold directly and through programmatic advertising networks. Affiliate commerce commission revenue is generated when Dotdash refers users to commerce partner websites resulting in a purchase or transaction. Applications Desktop revenue largely consists of advertising revenue generated principally through the display of paid listings in response to search queries. The substantial majority of the paid listings displayed by our Desktop businesses is supplied to us by Google Inc. ("Google") pursuant to our services agreement with Google. Pursuant to this agreement, those of our Desktop businesses that provide search services transmit search queries to Google, which in turn transmits a set of relevant and responsive paid listings back to these businesses for display in search results. This ad-serving process occurs independently of, but concurrently with, the generation of algorithmic search results for the same search queries. Google paid listings are displayed separately from algorithmic search results and are identified as sponsored listings on search results pages. Paid listings are priced on a price per click basis and when a user submits a search query through one of our Desktop businesses and then clicks on a Google paid listing displayed in response to the query, Google bills the advertiser that purchased the paid listing directly and shares a portion of the fee charged to the advertiser with us. The Company recognizes paid listing revenue from Google when it delivers the user's click. In cases where the user’s click is generated due to the efforts of a third-party distributor, we recognize the amount due from Google as revenue and record a revenue share or other payment obligation to the third-party distributor as traffic acquisition costs. To a lesser extent, Desktop revenue also includes fees related to subscription downloadable desktop applications as well as display advertisements. Fees related to subscription downloadable desktop applications are generally recognized over the term of the applicable subscription period, which is primarily one or two years . Fees related to display advertisements are recognized when an advertisement is displayed. Mosaic Group revenue consists primarily of fees related to subscription downloadable mobile applications distributed through the Apple App and Google Play stores, as well as display advertisements. Fees related to subscription downloadable mobile applications are generally recognized at the time of the sale when the software license is delivered. To the extent updates or maintenance is required or expected, revenue is recognized over the term of the applicable subscription period, which is primarily one or two years . Fees related to display advertisements are recognized when an advertisement is displayed. Emerging & Other Revenue of Ask Media Group consists principally of advertising revenue, which is generated primarily through the display of paid listings in response to search queries and display advertisements (sold directly and through programmatic ad sales). The majority of the paid listings displayed are supplied to us by Google in the manner, and pursuant to the services agreement with Google, described above under "Applications." The Daily Beast revenue consists of advertising revenue, which is generated primarily through display advertisements (sold directly and through programmatic ad sales). BlueCrew revenue consists of service revenue, which is generated through staffing temporary workers and recognized as control of the promised services is transferred to our customers. Revenue of College Humor Media and IAC Films is generated primarily through media production and distribution and advertising. Production revenue is recognized when control is transferred to the customer to broadcast or exhibit, and advertising revenue is recognized when an advertisement is displayed or over the advertising period. Accounts Receivables, Net of Allowance for Doubtful Accounts and Revenue Reserves Accounts receivable include amounts billed and currently due from customers. The Company maintains an allowance for doubtful accounts to provide for the estimated amount of accounts receivable that will not be collected. The allowance for doubtful accounts is based upon a number of factors, including the length of time accounts receivable are past due, the Company’s previous loss history and the specific customer’s ability to pay its obligation. The time between the Company issuance of an invoice and payment due date is not significant; customer payments that are not collected in advance of the transfer of promised services or goods are generally due no later than 30 days from invoice date. The Company also maintains allowances to reserve for potential credits issued to consumers or other revenue adjustments. The amounts of these reserves are based primarily upon historical experience. Deferred Revenue Deferred revenue consists of advance payments that are received or are contractually due in advance of the Company's performance. The Company’s deferred revenue is reported on a contract by contract basis at the end of each reporting period. The Company classifies deferred revenue as current when the term of the applicable subscription period or expected completion of our performance obligation is one year or less. The deferred revenue balance at January 1, 2018 is $332.2 million . During the year ended December 31, 2018, the Company recognized $330.2 million of revenue that was included in the deferred revenue balance as of January 1, 2018. The current and non-current deferred revenue balances at December 31, 2018 are $360.0 million and $1.7 million , respectively. Non-current deferred revenue is included in "Other long-term liabilities" in the accompanying consolidated balance sheet. Cash and Cash Equivalents Cash and cash equivalents include cash and short-term investments, with maturities of less than 91 days from the date of purchase. Domestically, cash equivalents primarily consist of AAA rated government money market funds, treasury discount notes, commercial paper rated A1/P1 or better, time deposits and certificates of deposit. Internationally, cash equivalents primarily consist of AAA rated government money market funds and time deposits. Investments in Debt Securities The Company invests in marketable debt securities with active secondary or resale markets to ensure portfolio liquidity to fund current operations or satisfy other cash requirements as needed. Marketable debt securities are adjusted to fair value each quarter, and the unrealized gains and losses, net of tax, are included in accumulated other comprehensive income (loss) as a separate component of shareholders' equity. The specific-identification method is used to determine the cost of debt securities sold and the amount of unrealized gains and losses reclassified out of accumulated other comprehensive income (loss) into earnings. The Company also invests in non-marketable debt securities as part of its investment strategy. We review our debt securities for impairment each reporting period. The Company recognizes an unrealized loss on debt securities in net earnings when the impairment is determined to be other-than-temporary. Factors we consider in making such determination include the duration, severity and reason for the decline in value and the potential recovery and our intent to sell the debt security. We also consider whether we will be required to sell the security before recovery of its amortized cost basis and whether the amortized cost basis cannot be recovered because of credit losses. If an impairment is considered to be other-than-temporary, the debt security will be written down to its fair value and the loss will be recognized within other income (expense), net. At December 31, 2018, marketable debt securities consist of treasury discount notes and commercial paper rated A1/P1 or better. Certain Risks and Concentrations A meaningful portion of the Company's revenue is derived from online advertising, the market for which is highly competitive and rapidly changing. Significant changes in this industry or changes in advertising spending behavior or in customer buying behavior could adversely affect our operating results. Most of the Company's online advertising revenue is attributable to a services agreement with Google Inc. ("Google"). For the years ended December 31, 2018 , 2017 and 2016 , consolidated revenue earned from Google w as $825.2 million , $740.7 million and $824.4 million , representing 19% , 22% and 26% , respectively, of the Company's consolidated revenue. A meaningful portion of this revenue is attributable to the service agreement with Google and earned by the Desktop business within the Applications segment and the Ask Media Group within the Emerging & Other segment. For the y ears end ed December 31, 2018 , 2017 and 2016 , revenue earned from Google represents 73% , 83% and 87% of Applications revenue and 94% , 96% and 96% of Ask Media Group revenue (and 68% , 48% and 35% of Emerging & Other revenue), respectively. Accounts receivable related to revenue earned from Google totaled $69.1 million and $72.4 million at December 31, 2018 and 2017 , respectively. The services agreement became effective on April 1, 2016, following the expiration of the previous services agreement, and expires on March 31, 2020. The services agreement requires that the Company comply with certain guidelines promulgated by Google. Google may generally unilaterally update its policies and guidelines without advance notice, which could in turn require modifications to, or prohibit and/or render obsolete certain of our products, services and/or business practices, which could be costly to address or otherwise have an adverse effect on our business, financial condition and results of operations. Google’s policy changes related to its Chrome browser became effective on September 12, 2018 and negatively impacted the distribution of our business-to-consumer ("B2C") desktop products. The impact of these changes on revenue and profits in 2018 were modest as the Company optimized marketing spend in anticipation of the changes. However, we expect these changes to reduce revenue and profits of the Desktop business in the future, which among other reasons led to a $27.7 million impairment of the related indefinite-lived intangible asset in the fourth quarter of 2018. See " Note 21—Subsequent Events (Unaudited) " for a discussion of the Company's amended services agreement with Google entered into on February 11, 2019. The Company's business is subject to certain risks and concentrations including dependence on third-party technology providers, exposure to risks associated with online commerce security and credit card fraud. Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash and cash equivalents and marketable securities. Cash and cash equivalents are maintained with financial institutions and are in excess of Federal Deposit Insurance Corporation insurance limits. Property and Equipment Property and equipment, including significant improvements, are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, or, in the case of leasehold improvements, the lease term, if shorter. Asset Category Estimated Useful Lives Buildings and leasehold improvements 3 to 39 Years Computer equipment and capitalized software 2 to 3 Years Furniture and other equipment 3 to 12 Years The Company capitalizes certain internal use software costs including external direct costs utilized in developing or obtaining the software and compensation for personnel directly associated with the development of the software. Capitalization of such costs begins when the preliminary project stage is complete and ceases when the project is substantially complete and ready for its intended purpose. The net book value of capitalized internal use software is $58.1 million and $46.4 million at December 31, 2018 and 2017 , respectively. Business Combinations The purchase price of each acquisition is attributed to the assets acquired and liabilities assumed based on their fair values at the date of acquisition, including identifiable intangible assets that either arise from a contractual or legal right or are separable from goodwill. The fair value of these intangible assets is based on valuations that use information and assumptions provided by management. The excess purchase price over the net tangible and identifiable intangible assets is recorded as goodwill and is assigned to the reporting unit(s) that is expected to benefit from the combination as of the acquisition date. In connection with certain business combinations, the Company has entered into contingent consideration arrangements that are determined to be part of the purchase price. Each of these arrangements is initially recorded at its fair value at the time of the acquisition and reflected at current fair value for each subsequent reporting period thereafter until settled. The contingent consideration arrangements are generally based upon earnings performance and/or operating metrics. The Company determines the fair value of the contingent consideration arrangements using probability-weighted analyses to determine the amounts of the gross liability, and, if the arrangement is long-term in nature, applying a discount rate that appropriately captures the risk associated with the obligation to determine the net amount reflected in the consolidated financial statements. Significant changes in forecasted earnings or operating metrics would result in a significantly higher or lower fair value measurement. The changes in the remeasured fair value of the contingent consideration arrangements during each reporting period, including the accretion of the discount, if applicable, are recognized in "General and administrative expense" in the accompanying consolidated statement of operations. See " Note 6—Financial Instruments " for a discussion of contingent consideration arrangements. Goodwill and Indefinite-Lived Intangible Assets The Company assesses goodwill and indefinite-lived intangible assets for impairment annually as of October 1, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit or the fair value of an indefinite-lived intangible asset below its carrying value. When the Company elects to perform a qualitative assessment and concludes it is not more likely than not that the fair value of the reporting unit is less than its carrying value, no further assessment of that reporting unit's goodwill is necessary; otherwise, a quantitative assessment is performed and the fair value of the reporting unit is determined. If the carrying value of the reporting unit exceeds its fair value, an impairment equal to the excess is recorded. For the Company's annual goodwill test at October 1, 2018, a qualitative assessment of the MTCH, ANGI, Vimeo, College Humor Media and BlueCrew reporting units' goodwill was performed because the Company concluded it was more likely than not that the fair value of these reporting units was in excess of their respective carrying values. The primary fact ors that the Company considered in its qualitative assessment for each of these reporting units are described below: • MTCH's October 1, 2018 market capitalization of $15.7 billion exceeded its carrying value by approximately $15.1 billion and MTCH's strong operating performance. • ANGI's October 1, 2018 market capitalization of $10.7 billion exceeded its carrying value by approximately $9.6 billion and ANGI's strong operating performance. • The Company performed valuations of the Vimeo, College Humor Media and BlueCrew reporting units during 2018. These valuations were prepared primarily in connection with the issuance and/or settlement of equity grants that are denominated in the equity of these businesses. The valuations were prepared time proximate to, however, not as of, October 1, 2018. The fair value of each of these businesses was in excess of its October 1, 2018 carrying value. The Company tests goodwill for impairment when it concludes that it is more likely than not that there may be an impairment. For the Company's annual goodwill test at October 1, 2018, the Company quantitatively tested the Desktop and Mosaic Group reporting units (included in the Applications segment). The Company's quantitative test indicated that the fair value of these reporting units are in excess of their respective carrying values; therefore, the goodwill of these reporting units are not impaired. The Company's Dotdash, Ask Media Group and The Daily Beast reporting units have no goodwill. The aggregate goodwill balance for the reporting units for which the most recent estimate of fair value is less than 110% of their carrying values is approximately $265.1 million . The fair value of the Company's reporting units (except for MTCH and ANGI described above) is determined using both an income approach based on discounted cash flows ("DCF") and a market approach when it tests goodwill for impairment, either on an interim basis or annual basis as of October 1 each year. The Company uses the same approach in determining the fair value of its businesses in connection with its non-public subsidiary denominated stock-based compensation plans, which can be a significant factor in the decision to apply the qualitative screen. Determining fair value using a DCF analysis requires the exercise of significant judgment with respect to several items, including the amount and timing of expected future cash flows and appropriate discount rates. The expected cash flows used in the DCF analyses are based on the Company's most recent forecast and budget and, for years beyond the budget, the Company's estimates, which are based, in part, on forecasted growth rates. The discount rates used in the DCF analyses are intended to reflect the risks inherent in the expected future cash flows of the respective reporting units. Assumptions used in the DCF analyses, including the discount rate, are assessed based on each reporting unit's current results and forecasted future performance, as well as macroeconomic and industry specific factors. The discount rates used in the quantitative test for determining the fair value of the Company's reporting units ranged from 12.5% to 15% in 2018 and 12.5% to 17.5% in 2017. Determining fair value using a market approach considers multiples of financial metrics based on both acquisitions and trading multiples of a selected peer gr oup of companies. From the comparable companies, a representative market multiple is determined which is applied to financial metrics to estimate the fair value of a reporting unit. To determine a peer group of companies for our respective reporting units, we considered companies relevant in terms of consumer use, monetization model, margin and growth characteristics, and brand strength operating in their respective sectors. While a primary driver in the determination of the fair values of the Company's reporting units is the estimate of future revenue and profitability, the determination of fair value is based, in part, upon the Company's assessment of macroeconomic factors, industry and competitive dynamics and the strategies of its businesses in response to these factors. While the Company has the option to qualitatively assess whether it is more likely than not that the fair values of its indefinite-lived intangible assets are less than their carrying values, the Company's policy is to determine the fair value of each of its indefinite-lived intangible assets annually as of October 1. The Company determines the fair value of indefinite-lived intangible assets using an avoided royalty DCF valuation analysis. Significant judgments inherent in this analysis include the selection of appropriate royalty and discount rates and estimating the amount and timing of expected future cash flows. The discount rates used in the DCF analyses are intended to reflect the risks inherent in the expected fut

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES U.S. and foreign earnings (loss) before income taxes and noncontrolling interests are as follows: Years Ended December 31, 2018 2017 2016 (In thousands) U.S. $ 630,417 $ (52,606 ) $ (248,433 ) Foreign 131,141 119,564 167,348 Total $ 761,558 $ 66,958 $ (81,085 ) The components of the income tax provision (benefit) are as follows: Years Ended December 31, 2018 2017 2016 (In thousands) Current income tax provision (benefit): Federal $ (2,849 ) $ (31,844 ) $ 23,343 State 2,569 1,964 3,662 Foreign 38,770 24,108 27,242 Current income tax provision (benefit) 38,490 (5,772 ) 54,247 Deferred income tax provision (benefit): Federal (21,792 ) (255,477 ) (100,798 ) State 172 (28,364 ) (9,518 ) Foreign (13,059 ) (1,437 ) (8,865 ) Deferred income tax benefit (34,679 ) (285,278 ) (119,181 ) Income tax provision (benefit) $ 3,811 $ (291,050 ) $ (64,934 ) The tax provision for the year ended December 31, 2018 includes a $143.3 million benefit for excess tax deductions attributable to stock-based compensation. Of this amount, $142.2 million reduced income taxes payable and $1.1 million increased the deferred tax asset for net operating losses ("NOLs"). The deferred tax asset for NOLs was increased by $361.8 million for the year ended December 31, 2017 for excess tax deductions attributable to stock-based compensation. The related income tax benefit was recorded as a component of the deferred income tax benefit. The current income tax payable was reduced by $51.8 million for the year ended December 31, 2016 for excess tax deductions attributable to stock-based compensation. For the year ended December 31, 2016 , the related income tax benefits were recorded as increases to additional paid-in capital. Income taxes receivable (payable) and deferred tax assets (liabilities) are included in the following captions in the accompanying consolidated balance sheet at December 31, 2018 and 2017 : December 31, 2018 2017 (In thousands) Income taxes receivable (payable): Other current assets $ 10,132 $ 33,239 Other non-current assets 11,401 1,949 Accrued expenses and other current liabilities (12,745 ) (11,798 ) Income taxes payable (37,584 ) (25,624 ) Net income taxes payable $ (28,796 ) $ (2,234 ) Deferred tax assets (liabilities): Other non-current assets $ 64,786 $ 66,321 Deferred income taxes (23,600 ) (35,070 ) Net deferred tax assets $ 41,186 $ 31,251 The tax effects of cumulative temporary differences that give rise to significant deferred tax assets and deferred tax liabilities are presented below. The valuation allowance relates to deferred tax assets for which it is more likely than not that the tax benefit will not be realized. December 31, 2018 2017 (In thousands) Deferred tax assets: Accrued expenses $ 23,525 $ 22,234 NOL carryforwards 291,639 292,812 Tax credit carryforwards 89,397 78,715 Stock-based compensation 82,698 77,976 Other 30,106 42,331 Total deferred tax assets 517,365 514,068 Less valuation allowance (115,853 ) (132,598 ) Net deferred tax assets 401,512 381,470 Deferred tax liabilities: Investment in subsidiaries (238,650 ) (247,167 ) Intangibles (77,669 ) (87,811 ) Fair value investment (22,927 ) — Other (21,080 ) (15,241 ) Total deferred tax liabilities (360,326 ) (350,219 ) Net deferred tax assets $ 41,186 $ 31,251 At December 31, 2018 , the Company has federal and state NOLs of $856.0 million and $698.7 million , respectively. If not utilized, $13.9 million of federal NOLs can be carried forward indefinitely, and the remainder will expire at various times primarily between 2023 and 2037, and the state NOLs, if not utilized, will expire at various times between 2019 and 2038. Federal and state NOLs of $569.9 million and $350.4 million , respectively, can be used against future taxable income without restriction and the remaining NOLs will be subject to limitations under Section 382 of the Internal Revenue Code, separate return limitations, and applicable state law. At December 31, 2018 , the Company has foreign NOLs of $383.4 million available to offset future income. Of these foreign NOLs, $352.0 million can be carried forward indefinitely and $31.4 million will expire at various times between 2019 and 2038. During 2018 , the Company recognized tax benefits related to NOLs of $9.5 million . At December 31, 2018 , the Company has tax credit carryforwards of $105.4 million . Of this amount, $53.2 million relates to credits for foreign taxes, $48.3 million relates to credits for research activities and $3.9 million relates to various other credits. Of these credit carryforwards, $24.2 million can be carried forward indefinitely and $81.2 million will expire between 2019 and 2038. The Company regularly assesses the realizability of deferred tax assets considering all available evidence including, to the extent applicable, the nature, frequency and severity of prior cumulative losses, forecasts of future taxable income, tax filing status, the duration of statutory carryforward periods, available tax planning and historical experience. During 2018 , the Company's valuation allowance decreased by $16.7 million primarily due to a decrease in foreign tax credits subject to valuation allowance and the realization of previously unbenefited capital losses. At December 31, 2018 , the Company has a valuation allowance of $115.9 million related to the portion of tax loss carryforwards, foreign tax credits and other items for which it is more likely than not that the tax benefit will not be realized. A reconciliation of the income tax provision (benefit) to the amounts computed by applying the statutory federal income tax rate to earnings before income taxes is shown as follows: Years Ended December 31, 2018 2017 2016 (In thousands) Income tax provision (benefit) at the federal statutory rate of 21% (35% for 2017 and 2016) $ 159,927 $ 23,435 $ (28,446 ) State income taxes, net of effect of federal tax benefit 14,887 86 (3,880 ) Stock-based compensation (129,654 ) (358,901 ) 3,998 Realization of certain deferred tax assets (13,200 ) (3,133 ) — Transition tax (9,190 ) 62,667 — Deferred tax adjustment for enacted changes in tax laws and rates (7,488 ) 705 (4,594 ) Research credit (4,023 ) (5,304 ) (2,231 ) Foreign income taxed at a different statutory tax rate (3,206 ) (14,725 ) (27,115 ) Non-taxable sale and non-deductible goodwill associated with ShoeBuy — — (13,142 ) Goodwill impairment of Dotdash and Emerging & Other — — 10,649 Non-deductible impairments for certain cost method investments — 2,669 3,489 Other, net (4,242 ) 1,451 (3,662 ) Income tax provision (benefit) $ 3,811 $ (291,050 ) $ (64,934 ) A reconciliation of the beginning and ending amount of unrecognized tax benefits, including penalties but excluding interest, is as follows: December 31, 2018 2017 2016 (In thousands) Balance at January 1 $ 36,732 $ 38,372 $ 40,808 Additions based on tax positions related to the current year 10,334 2,050 2,033 Additions for tax positions of prior years 4,716 1,994 2,676 Reductions for tax positions of prior years (400 ) (3,761 ) (743 ) Settlements — — (5,107 ) Expiration of applicable statutes of limitations (2,507 ) (1,923 ) (1,295 ) Balance at December 31 $ 48,875 $ 36,732 $ 38,372 The Company recognizes interest and, if applicable, penalties related to unrecognized tax benefits in the income tax provision. Included in the income tax provision for the years ended December 31, 2018 , 2017 and 2016 is a $0.3 million expense, $0.1 million benefit and $0.4 million expense, respectively, net of related deferred taxes of $0.1 million , less than $0.1 million and $0.2 million , respectively, for interest on unrecognized tax benefits. At December 31, 2018 and 2017 , the Company has accrued $3.4 million and $3.0 million , respectively, for the payment of interest. At December 31, 2018 and 2017 , the Company has accrued $1.4 million and $1.7 million , respectively, for penalties. The Company is routinely under audit by federal, state, local and foreign authorities in the area of income tax. These audits include questioning the timing and the amount of income and deductions and the allocation of income and deductions among various tax jurisdictions. The Internal Revenue Service ("IRS") is currently auditing the Company’s federal income tax returns for the years ended December 31, 2010 through 2016. The statute of limitations for the years 2010 through 2015 has been extended to December 31, 2019. Various other jurisdictions are open to examination for tax years beginning with 2009. Income taxes payable include unrecognized tax benefits considered sufficient to pay assessments that may result from examination of prior year tax returns. We consider many factors when evaluating and estimating our tax positions and tax benefits, which may not accurately anticipate actual outcomes and, therefore, may require periodic adjustment. Although management currently believes changes in unrecognized tax benefits from period to period and differences between amounts paid, if any, upon resolution of issues raised in audits and amounts previously provided will not have a material impact on the liquidity, results of operations, or financial condition of the Company, these matters are subject to inherent uncertainties and management’s view of these matters may change in the future. At December 31, 2018 and 2017 , unrecognized tax benefits, including interest and penalties, were $52.3 million and $39.7 million , respectively. If unrecognized tax benefits at December 31, 2018 are subsequently recognized, $49.1 million , net of related deferred tax assets and interest, would reduce income tax expense. The comparable amount as of December 31, 2017 was $37.2 million . The Company believes that it is reasonably possible that its unrecognized tax benefits could decrease by $21.6 million by December 31, 2019, due to expirations of statutes of limitations or other settlements; $21.6 million of which would reduce the income tax provision. On December 22, 2017, the U.S. enacted the Tax Act. The Tax Act subjected to U.S. taxation certain previously deferred earnings of foreign subsidiaries as of December 31, 2017 ("Transition Tax") and implemented a number of changes that took effect on January 1, 2018, including but not limited to, a reduction of the U.S. federal corporate tax rate from 35% to 21% and a new minimum tax on GILTI earned by foreign subsidiaries. The Company was able to make a reasonable estimate of the Transition Tax and recorded a provisional tax expense in the fourth quarter of 2017. In the third quarter of 2018, the Company finalized this calculation, which resulted in a $9.2 million reduction in the Transition Tax. The net reduction in the Transition Tax was due primarily to the utilization of additional foreign tax credits and a reduction in state taxes, partially offset by additional taxable earnings and profits of our foreign subsidiaries based on recently issued IRS guidance. The adjustment of the Company’s provisional tax expense was recorded as a change in estimate in accordance with Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act , which is also included in the FASB issued ASU No. 2018-05, Income Taxes (Topic 740), Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 ("SAB 118"), which was issued and adopted by the Company in March 2018. Despite the completion of the Company’s accounting for the Tax Act under SAB 118, many aspects of the law remain unclear and we expect ongoing guidance to be issued at both the federal and state levels. We will continue to monitor and assess the impact of any new developments. At December 31, 2018 , all of the Company’s international cash can be repatriated without significant tax consequences. The Company has not provided for approximately $1.0 million of foreign deferred taxes for the $103.1 million of the foreign cash earnings that is indefinitely reinvested outside the U.S. The Company reassesses its intention to remit or permanently reinvest these cash earnings each reporting period; any required adjustment to the income tax provision would be reflected in the period that the Company changes this intention.

BUSINESS COMBINATION

BUSINESS COMBINATION	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
BUSINESS COMBINATION	BUSINESS COMBINATION Through the Combination, ANGI acquired 100% of the common stock of Angie's List on September 29, 2017 for a total purchase price valued at $781.4 million . The purchase price of $781.4 million was determined based on the sum of (i) the fair value of the 61.3 million shares of Angie's List common stock outstanding immediately prior to the Combination based on the closing stock price of Angie's List common stock on the NASDAQ on September 29, 2017 of $12.46 per share; (ii) the cash consideration of $1.9 million paid to holders of Angie's List common stock who elected to receive $8.50 in cash per share; and (iii) the fair value of vested equity awards (including the pro rata portion of unvested awards attributable to pre-combination services) outstanding under Angie's List stock plans on September 29, 2017 . Each stock option to purchase shares of Angie's List common stock that was outstanding immediately prior to the effective time of the Combination was, as of the effective time of the Combination, converted into an option to purchase (i) that number of Class A shares of ANGI Homeservices equal to the total number of shares of Angie's List common stock subject to such Angie's List option immediately prior to the effective time of the Combination, (ii) at a per-share exercise price equal to the exercise price per share of Angie's List common stock at which such Angie's List option was exercisable immediately prior to the effective time of the Combination. Each award of Angie's List restricted stock units that was outstanding immediately prior to the effective time of the Combination was, as of the effective time of the Combination, converted into an ANGI Homeservices restricted stock unit award with respect to a number of Class A shares of ANGI Homeservices equal to the total number of shares of Angie's List common stock subject to such Angie's List restricted stock unit award immediately prior to the effective time of the Combination. The table below summarizes the purchase price: Angie's List (In thousands) Class A common stock $ 763,684 Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock 1,913 Fair value of vested and pro rata portion of unvested stock options attributable to pre-combination services 11,749 Fair value of the pro rata portion of unvested restricted stock units attributable to pre-combination services 4,038 Total purchase price $ 781,384 The financial results of Angie's List are included in the Company's consolidated financial statements, within the ANGI Homeservices segment, beginning September 29, 2017 . For the year ended December 31, 2017 , the Company included $58.9 million of revenue and $21.8 million of net loss in its consolidated statement of operations related to Angie's List. The net loss of Angie's List reflects $28.7 million in stock-based compensation expense related to (i) the acceleration of previously issued Angie's List equity awards held by employees terminated in connection with the Combination and (ii) the expense related to previously issued Angie's List equity awards, severance and retention costs of $19.8 million related to the Combination and a reduction in revenue of $7.8 million due to the write-off of deferred revenue related to the Combination. The table below summarizes the fair values of the assets acquired and liabilities assumed at the date of combination: Angie's List (In thousands) Cash and cash equivalents $ 44,270 Other current assets 11,280 Property and equipment 16,341 Goodwill 543,674 Intangible assets 317,300 Total assets 932,865 Deferred revenue (32,595 ) Other current liabilities (46,150 ) Long-term debt—related party (61,498 ) Deferred income taxes (9,833 ) Other long-term liabilities (1,405 ) Net assets acquired $ 781,384 The purchase price was based on the expected financial performance of Angie's List, not on the value of the net identifiable assets at the time of combination. This resulted in a significant portion of the purchase price being attributed to goodwill because Angie's List is complementary and synergistic to the other North America businesses of ANGI Homeservices. The fair values of the identifiable intangible assets acquired at the date of combination are as follows: Angie's List (In thousands) Weighted-Average Useful Life (Years) Indefinite-lived trade name and trademarks $ 137,000 Indefinite Service professionals 90,500 3 Developed technology 63,900 6 Memberships 15,900 3 User base 10,000 1 Total identifiable intangible assets acquired $ 317,300 Other current assets, current liabilities and other long-term liabilities of Angie's List were reviewed and adjusted to their fair values at the date of combination, as necessary. The fair value of deferred revenue was determined using an income approach that utilized a cost to fulfill analysis. The fair value of the trade name and trademarks was determined using an income approach that utilized the relief from royalty methodology. The fair values of developed technology and user base were determined using a cost approach that utilized the cost to replace methodology. The fair values of the service professionals and memberships were determined using an income approach that utilized the excess earnings methodology. The valuations of deferred revenue and intangible assets incorporate significant unobservable inputs and require significant judgment and estimates, including the amount and timing of future cash flows, cost and profit margins related to deferred revenue and the determination of royalty and discount rates. The amount attributed to goodwill is not tax deductible. Unaudited Pro Forma Financial Information The unaudited pro forma financial information in the table below presents the combined results of the Company and Angie's List as if the Combination had occurred on January 1, 2016. The unaudited pro forma financial information includes adjustments required under the acquisition method of accounting and is presented for informational purposes only and is not necessarily indicative of the results that would have been achieved had the Combination actually occurred on January 1, 2016. For the year ended December 31, 2017 , pro forma adjustments include (i) reductions in stock-based compensation expense of $77.1 million and transaction related costs of $34.1 million because they are one-time in nature and will not have a continuing impact on operations; and (ii) an increase in amortization of intangibles of $31.9 million . The stock-based compensation expense is related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination. The transaction related costs include severance and retention costs of $19.8 million related to the Combination. For the year ended December 31, 2016, pro forma adjustments include a reduction in revenue of $34.1 million due to the write-off of deferred revenue at the assumed date of acquisition as well as increases in stock-based compensation expense of $81.4 million and amortization of intangibles of $56.1 million . Years Ended December 31, 2017 2016 (In thousands, except per share data) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to ANGI Homeservices Inc. shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.27 $ (1.79 ) TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION During the years ended December 31, 2018 and 2017, the Company incurred $3.6 million and $44.1 million , respectively, in costs related to the Combination (including severance, retention, transaction and integration related costs), as well as deferred revenue write-offs of $5.5 million and $7.8 million , respectively. During the years ended December 31, 2018 and 2017, the Company also incurred $70.6 million and $122.1 million , respectively, in stock-based compensation expense related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination. See " Note 4—Business Combination " for additional information on the Combination. A summary of the costs incurred, payments made and the related accrual is presented below. Years Ended December 31, 2018 2017 (In thousands) Transaction and integration related costs $ 3,584 $ 44,101 Stock-based compensation expense 70,645 122,066 Total $ 74,229 $ 166,167 December 31, 2018 2017 (In thousands) Accrual as of January 1 $ 8,480 $ — Costs incurred 3,584 44,101 Payments made (12,064 ) (35,621 ) Accrual as of December 31 $ — $ 8,480 The costs are allocated as follows in the accompanying consolidated statement of operations: Year Ended December 31, 2018 Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense — 2,161 2,161 General and administrative expense 3,584 61,010 64,594 Product development expense — 7,474 7,474 Total $ 3,584 $ 70,645 $ 74,229 Year Ended December 31, 2017 Transaction and Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense 7,430 24,416 31,846 General and administrative expense 36,120 83,420 119,540 Product development expense 551 14,230 14,781 Total $ 44,101 $ 122,066 $ 166,167

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill and intangible assets, net are as follows: December 31, 2018 2017 (In thousands) Goodwill $ 2,726,859 $ 2,559,066 Intangible assets with indefinite lives 458,104 459,143 Intangible assets with definite lives, net of accumulated amortization 173,318 204,594 Total goodwill and intangible assets, net $ 3,358,281 $ 3,222,803 The following table presents the balance of goodwill by reportable segment, including the changes in the carrying value of goodwill, for the year ended December 31, 2018 : Balance at Additions (Deductions) Transfers In/(Out) Foreign Balance at (In thousands) Match Group $ 1,247,899 $ 11,187 $ — $ — $ (14,073 ) $ 1,245,013 ANGI Homeservices 768,317 142,768 (14,373 ) — (3,912 ) 892,800 Vimeo 77,303 — (151 ) — — 77,152 Applications: Desktop 265,146 — — — — 265,146 Mosaic Group 182,096 50,784 — 7,323 (457 ) 239,746 Total Applications 447,242 50,784 — 7,323 (457 ) 504,892 Emerging & Other 18,305 3,684 (7,664 ) (7,323 ) — 7,002 Total $ 2,559,066 $ 208,423 $ (22,188 ) $ — $ (18,442 ) $ 2,726,859 Additions primarily relate to the acquisitions of Handy (included in the ANGI Homeservices segment), TelTech and iTranslate (included in the Applications segment), Hinge (included in the Match Group segment), and BlueCrew (included in the Emerging & Other segment). Deductions relate to the sales of Felix (included in the ANGI Homeservices segment) and Electus (included in the Emerging & Other segment). The following table presents the balance of goodwill by reportable segment, including the changes in the carrying value of goodwill, for the year ended December 31, 2017 : Balance at Additions (Deductions) Foreign Balance at (In thousands) Match Group $ 1,206,538 $ 255 $ — $ 41,106 $ 1,247,899 ANGI Homeservices 170,611 590,772 — 6,934 768,317 Vimeo 9,649 67,654 — — 77,303 Applications: Desktop 265,146 — — — 265,146 Mosaic Group 182,096 — — — 182,096 Total Applications 447,242 — — — 447,242 Emerging & Other 90,012 2,715 (74,430 ) 8 18,305 Total $ 1,924,052 $ 661,396 $ (74,430 ) $ 48,048 $ 2,559,066 Additions primarily relate to the acquisitions of Angie's List, MyBuilder and HomeStars (included in the ANGI Homeservices segment), and Livestream (included in the Vimeo segment). Deductions relate to the sale of The Princeton Review (included in the Emerging & Other segment). Prior to the fourth quarter of 2018, IAC Publishing was a reportable segment consisting of one operating segment and one reporting unit. In the fourth quarter of 2018, IAC Publishing was split into the Dotdash and the Emerging & Other segments (related to the remaining businesses previously included in the IAC Publishing segment). The accumulated goodwill impairment of IAC Publishing was allocated to these businesses based upon their relative fair values as of October 1, 2018. The December 31, 2018 and 2017 goodwill balance reflects accumulated impairment losses of $529.1 million , $399.7 million , $198.3 million and $11.6 million at Applications, the businesses previously included in the IAC Publishing segment, excluding Dotdash (included in the Emerging & Other segment), Dotdash and College Humor Media (included in the Emerging & Other segment), respectively. Intangible assets with indefinite lives are trade names and trademarks acquired in various acquisitions. At December 31, 2018 and 2017 , intangible assets with definite lives are as follows: December 31, 2018 Gross Accumulated Net Weighted-Average (In thousands) Technology $ 143,303 $ (53,199 ) $ 90,104 4.7 Service professional and contractor relationships 99,528 (44,674 ) 54,854 2.9 Customer lists and user base 30,099 (15,126 ) 14,973 2.9 Memberships 15,900 (6,640 ) 9,260 3.0 Trade names 12,393 (9,393 ) 3,000 3.3 Other 8,500 (7,373 ) 1,127 4.8 Total $ 309,723 $ (136,405 ) $ 173,318 3.8 December 31, 2017 Gross Accumulated Net Weighted-Average (In thousands) Technology $ 115,200 $ (37,357 ) $ 77,843 4.8 Service professional and contractor relationships 99,497 (11,452 ) 88,045 3.0 Customer lists and user base 23,468 (5,401 ) 18,067 2.2 Memberships 15,900 (1,340 ) 14,560 3.0 Trade names 16,986 (13,634 ) 3,352 2.6 Other 8,500 (5,773 ) 2,727 4.8 Total $ 279,551 $ (74,957 ) $ 204,594 3.7 At December 31, 2018 , amortization of intangible assets with definite lives for each of the next five years and thereafter is estimated to be as follows: Years Ending December 31, (In thousands) 2019 $ 71,155 2020 51,916 2021 19,433 2022 16,310 2023 10,239 Thereafter 4,265 Total $ 173,318

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS Marketable Securities At December 31, 2018 and 2017, the fair value of marketable securities are as follows: December 31, 2018 2017 (In thousands) Available-for-sale marketable debt securities $ 123,246 $ 4,995 Marketable equity security 419 — Total marketable securities $ 123,665 $ 4,995 At December 31, 2018 , current available-for-sale marketable debt securities are as follows: Amortized Gross Gross Fair Value (In thousands) Treasury discount notes $ 112,291 $ 3 $ (3 ) $ 112,291 Commercial paper 10,955 — — 10,955 Total available-for-sale marketable debt securities $ 123,246 $ 3 $ (3 ) $ 123,246 The contractual maturities of debt securities classified as current available-for-sale at December 31, 2018 are within one year . There are no investments in available-for-sale marketable debt securities that have been in a continuous unrealized loss position for longer than twelve months as of December 31, 2018 . At December 31, 2017 , current available-for-sale marketable debt securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 4,995 $ — $ — $ 4,995 Total available-for-sale marketable debt securities $ 4,995 $ — $ — $ 4,995 The following table presents the proceeds from maturities and sales of available-for-sale marketable debt securities and the related gross realized gains: December 31, 2018 2017 2016 (In thousands) Proceeds from maturities and sales of available-for-sale marketable debt securities $ 333,600 $ 114,350 $ 279,485 Gross realized gains — — 3,556 Gross realized gains from the maturities and sales of available-for-sale marketable debt securities for the year ended December 31, 2016 are included in "Other income (expense), net" in the accompanying consolidated statement of operations. There were no gross realized losses from the maturities and sales of available-for-sale marketable debt securities for the years ended December 31, 2018, 2017, and 2016. Long-term investments Long-term investments consist of: December 31, 2018 2017 (In thousands) Equity securities without readily determinable fair values $ 235,055 $ — Equity method investments — 1,559 Cost method investments — 63,418 Total long-term investments $ 235,055 $ 64,977 Equity securities without readily determinable fair values The following table presents a summary of realized and unrealized gains and losses recorded in other income (expense), net, as adjustments to the carrying value of equity securities without readily determinable fair values held as of December 31, 2018. The gross unrealized gains principally relate to the Company's remaining investments in an investee following the sale of a portion of the Company's investment during the second quarter of 2018. Year Ended December 31, 2018 (In thousands) Upward adjustments (gross unrealized gains) $ 128,986 Downward adjustments including impairments (gross unrealized losses) (4,931 ) Total $ 124,055 Realized and unrealized gains and losses for the Company's marketable equity security and investments without readily determinable fair values for the year ended December 31, 2018 are as follows: Year Ended December 31, 2018 (In thousands) Realized gains, net, for equity securities sold $ 27,874 Unrealized gains, net, on equity securities held 124,170 Total gains recognized, net, in other income (expense), net $ 152,044 Equity method investments In 2018 and 2017 , the Company recorded other-than-temporary impairment charges on certain of its investments of $0.6 million and $2.7 million , respectively. These charges are included in "Other income (expense), net" in the accompanying consolidated statement of operations. Cost method investments (prior to the adoption of ASU No. 2016-01) In 2017 and 2016 , the Company recorded $9.5 million and $10.0 million , respectively, of other-than-temporary impairment charges for certain of its investments as a result of our assessment of the near-term prospects and financial condition of the investees. These charges are included in "Other income (expense), net" in the accompanying consolidated statement of operations. On October 23, 2017, Match Group sold a cost method investment for net proceeds of $60.2 million . The gain on sale of $9.1 million is included in "Other income (expense), net" in the accompanying consolidated statement of operations. Fair Value Measurements The following tables present the Company's financial instruments that are measured at fair value on a recurring basis: December 31, 2018 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 880,815 $ — $ — $ 880,815 Treasury discount notes — 561,733 — 561,733 Commercial paper — 162,417 — 162,417 Time deposits — 90,036 — 90,036 Marketable securities: Treasury discount notes — 112,291 — 112,291 Commercial paper — 10,955 — 10,955 Marketable equity security 419 — — 419 Total $ 881,234 $ 937,432 $ — $ 1,818,666 Liabilities: Contingent consideration arrangements $ — $ — $ (28,631 ) $ (28,631 ) December 31, 2017 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 780,425 $ — $ — $ 780,425 Commercial paper — 215,325 — 215,325 Treasury discount notes — 100,457 — 100,457 Time deposits — 60,000 — 60,000 Certificates of deposit — 6,195 — 6,195 Marketable securities: Commercial paper — 4,995 — 4,995 Total $ 780,425 $ 386,972 $ — $ 1,167,397 Liabilities: Contingent consideration arrangements $ — $ — $ (2,647 ) $ (2,647 ) The Company's financial instruments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3) are its contingent consideration arrangements. Contingent Consideration Arrangements Years Ended December 31, 2018 2017 (In thousands) Balance at January 1 $ (2,647 ) $ (33,871 ) Total net (losses) gains: Included in earnings: Fair value adjustments (1,456 ) (5,801 ) Included in other comprehensive income (loss) 45 (1,404 ) Fair value at date of acquisition (25,521 ) — Settlements 948 38,429 Balance at December 31 $ (28,631 ) $ (2,647 ) Contingent consideration arrangements At December 31, 2018, the Company has two contingent consideration arrangements outstanding related to business acquisitions. One arrangement has a $2.0 million maximum contingent payment that has been earned and will be paid by the Company in the first quarter of 2019. The second arrangement has a total maximum contingent payment of $45.0 million . At December 31, 2018, the gross fair value of this arrangement, before unamortized discount, is $44.0 million . The contingent consideration arrangements are based upon earnings performance and/or operating metrics. The Company generally determines the fair value of the contingent consideration arrangements by using probability-weighted analyses to determine the amounts of the gross liability, and, because the arrangements were initially long-term in nature, applying a discount rate that appropriately captures the risks associated with the obligation to determine the net amount reflected in the consolidated financial statements. The fair values of the contingent consideration arrangements at December 31, 2018 reflect discount rates ranging from 12% to 25% . The fair values of the contingent consideration arrangements at December 31, 2017 reflect discount rates of 12% . The fair value of contingent consideration arrangements is sensitive to changes in the forecasts of earnings and/or the relevant operating metrics and changes in discount rates. The Company remeasures the fair value of the contingent consideration arrangements each reporting period, including the accretion of the discount, if applicable, and changes are recognized in "General and administrative expense" in the accompanying consolidated statement of operations. The contingent consideration arrangement liability at December 31, 2018 and 2017 includes a current portion of $2.0 million and $0.6 million , respectively, and non-current portion of $26.6 million and $2.0 million at December 31, 2018 and 2017, which are included in "Accrued expenses and other current liabilities" and "Other long-term liabilities," respectively, in the accompanying consolidated balance sheet. Financial instruments measured at fair value only for disclosure purposes The following table presents the carrying value and the fair value of financial instruments measured at fair value only for disclosure purposes: December 31, 2018 December 31, 2017 Carrying Fair Carrying Fair (In thousands) Current portion of long-term debt $ (13,750 ) $ (12,753 ) $ (13,750 ) $ (13,802 ) Long-term debt, net (a) (2,245,548 ) (2,460,204 ) (1,979,469 ) (2,168,108 ) _________________ (a) At December 31, 2018 and 2017, the carrying value of long-term debt, net includes unamortized original issue discount and debt issuance costs of $88.9 million and $109.1 million , respectively . Excluding the MTCH Credit Facility, the fair value of long-term debt, including the current portion, is estimated using observable market prices or indices for similar liabilities, which are Level 2 inputs. The Company considers the outstanding borrowings under the MTCH Credit Facility, which has a variable interest rate, to have a fair value equal to its carrying value.

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt consists of: December 31, 2018 2017 (In thousands) MTCH Debt: MTCH Term Loan due November 16, 2022 $ 425,000 $ 425,000 MTCH Credit Facility due December 7, 2023 260,000 — 6.375% Senior Notes due June 1, 2024 (the "6.375% MTCH Senior Notes"); interest payable each June 1 and December 1 400,000 400,000 5.00% Senior Notes due December 15, 2027 (the "5.00% MTCH Senior Notes"); interest payable each June 15 and December 15 450,000 450,000 Total MTCH long-term debt 1,535,000 1,275,000 Less: unamortized original issue discount 7,352 8,668 Less: unamortized debt issuance costs 11,737 13,636 Total MTCH debt, net 1,515,911 1,252,696 ANGI Debt: ANGI Term Loan due November 5, 2023 261,250 275,000 Less: current portion of ANGI Term Loan 13,750 13,750 Less: unamortized debt issuance costs 2,529 2,938 Total ANGI debt, net 244,971 258,312 IAC Debt: 0.875% Exchangeable Senior Notes due October 1, 2022 (the "Exchangeable Notes"); interest payable each April 1 and October 1 517,500 517,500 4.75% Senior Notes due December 15, 2022 (the "4.75% Senior Notes"); interest payable each June 15 and December 15 34,489 34,859 Total IAC long-term debt 551,989 552,359 Less: unamortized original issue discount 54,025 67,158 Less: unamortized debt issuance costs 13,298 16,740 Total IAC debt, net 484,666 468,461 Total long-term debt, net $ 2,245,548 $ 1,979,469 MTCH Senior Notes The 6.375% MTCH Senior Notes were issued on June 1, 2016. The proceeds of $400 million were used to prepay a portion of indebtedness outstanding under the MTCH Term Loan. At any time prior to June 1, 2019, these notes may be redeemed at a redemption price equal to the sum of the principal amount thereof, plus accrued and unpaid interest and a make-whole premium set forth in the indenture governing the notes. Thereafter, these notes may be redeemed at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed during the twelve-month period beginning on June 1 of the years indicated below: Year Percentage 2019 104.781 % 2020 103.188 % 2021 101.594 % 2022 and thereafter 100.000 % On December 4, 2017, MTCH issued $450 million aggregate principal amount of its 5.00% Senior Notes. The proceeds from these notes, along with cash on hand, were used to redeem the $445.2 million outstanding balance of the 6.75% MTCH Senior Notes, which were due on December 15, 2022, and pay the related call premium. At any time prior to December 15, 2022, the 5.00% MTCH Senior Notes may be redeemed at a redemption price equal to the sum of the principal amount thereof, plus accrued and unpaid interest and a make-whole premium set forth in the indenture governing the notes. Thereafter, these notes may be redeemed at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed during the twelve-month period beginning on December 15 of the years indicated below: Year Percentage 2022 102.500 % 2023 101.667 % 2024 100.833 % 2025 and thereafter 100.000 % The indentures governing the 6.375% and 5.00% MTCH Senior Notes (i) contain covenants that would limit MTCH's ability to pay dividends, make distributions or repurchase MTCH stock in the event a default has occurred or MTCH's consolidated leverage ratio (as defined in the indentures) exceeds 5.0 to 1.0 and (ii) are ranked equally with each other. At December 31, 2018 , there were no limitations pursuant thereto. There are additional covenants that limit MTCH's ability and the ability of its subsidiaries to, among other things, (i) incur indebtedness, make investments, or sell assets in the event MTCH is not in compliance with certain ratios set forth in the indentures, and (ii) incur liens, enter into agreements restricting MTCH subsidiaries' ability to pay dividends, enter into transactions with affiliates and consolidate, merge or sell substantially all of their assets. MTCH Term Loan and MTCH Credit Facility At both December 31, 2018 and 2017 , the outstanding balance on the MTCH Term Loan was $425 million . The MTCH Term Loan bears interest at LIBOR plus 2.50% and was 5.09% and 3.85% at December 31, 2018 and 2017 , respectively. The MTCH Term Loan provides for annual principal payments as part of an excess cash flow sweep provision, the amount of which, if any, is governed by the secured net leverage ratio contained in the credit agreement. Interest payments are due at least quarterly through the term of the loan. On December 7, 2018, the MTCH $500 million revolving credit facility (the "MTCH Credit Facility") was amended and restated, and is due on December 7, 2023. At December 31, 2018 , the outstanding borrowings under the MTCH Credit Facility were $260.0 million which bear interest at LIBOR plus 1.50% , or approximately 4.00% . At December 31, 2017 , there were no outstanding borrowings under the MTCH Credit Facility. The annual commitment fee on undrawn funds based on the current consolidated net leverage ratio is 25 basis points and 30 basis points at December 31, 2018 and 2017 , respectively. Borrowings under the MTCH Credit Facility bear interest, at MTCH's option, at a base rate or LIBOR, in each case plus an applicable margin, which is determined by reference to a pricing grid based on MTCH's consolidated net leverage ratio. The terms of the MTCH Credit Facility require MTCH to maintain a consolidated net leverage ratio of not more than 5.0 to 1.0 and a minimum interest coverage ratio of not less than 2.0 to 1.0 (in each case as defined in the agreement). The MTCH Term Loan and MTCH Credit Facility contain covenants that would limit MTCH’s ability to pay dividends, make distributions or repurchase MTCH stock in the event MTCH’s secured net leverage ratio exceeds 2.0 to 1.0 , while the MTCH Term Loan remains outstanding and, thereafter, if the consolidated net leverage ratio exceeds 4.0 to 1.0 , or in the event a default has occurred. There are additional covenants under these MTCH debt agreements that limit the ability of MTCH and its subsidiaries to, among other things, incur indebtedness, pay dividends or make distributions. Obligations under the MTCH Credit Facility and MTCH Term Loan are unconditionally guaranteed by certain MTCH wholly-owned domestic subsidiaries, and are also secured by the stock of certain MTCH domestic and foreign subsidiaries. The MTCH Term Loan and outstanding borrowings, if any, under the MTCH Credit Facility rank equally with each other, and have priority over the 6.375% and 5.00% MTCH Senior Notes to the extent of the value of the assets securing the borrowings under the MTCH credit agreement. ANGI Term Loan and ANGI Credit Facility On November 1, 2017, ANGI borrowed $275 million under a five-year term loan facility ("ANGI Term Loan"). On November 5, 2018, the ANGI Term Loan was amended and restated, and is now due on November 5, 2023. Interest payments are due at least quarterly through the term of the loan and quarterly principal payments of 1.25% of the original principal amount in the first three years from the amendment date, 2.50% in the fourth year and 3.75% in the fifth year are required. The ANGI Term Loan bears interest at LIBOR plus 1.50% , or approximately 4.00% at December 31, 2018 , which is subject to change in future periods based on ANGI's consolidated net leverage ratio. The ANGI Term Loan bore interest at LIBOR plus 2.00% , or 3.38% , at December 31, 2017 . The terms of the ANGI Term Loan require ANGI to maintain a consolidated net leverage ratio of not more than 4.5 to 1.0 and a minimum interest coverage ratio of not less than 2.0 to 1.0 (in each case as defined in the credit agreement). The ANGI Term Loan also contains covenants that would limit ANGI’s ability to pay dividends, make distributions or repurchase ANGI stock in the event a default has occurred or ANGI’s consolidated net leverage ratio exceeds 4.25 to 1.0. There are additional covenants under the ANGI Term Loan that limit the ability of ANGI and its subsidiaries to, among other things, incur indebtedness, pay dividends or make distributions. On November 5, 2018, ANGI entered into a five -year $250 million revolving credit facility (the "ANGI Credit Facility"). At December 31, 2018 , there were no outstanding borrowings under the ANGI Credit Facility. The annual commitment fee on undrawn funds is currently 25 basis points, and is based on the consolidated net leverage ratio most recently reported. Borrowings under the ANGI Credit Facility bear interest, at ANGI's option, at either a base rate or LIBOR, in each case plus an applicable margin, which is determined by reference to a pricing grid based on ANGI's consolidated net leverage ratio. The financial and other covenants are the same as those for the ANGI Term Loan. The ANGI Term Loan and ANGI Credit Facility are guaranteed by ANGI's wholly-owned material domestic subsidiaries and are secured by substantially all assets of ANGI and the guarantors, subject to certain exceptions. IAC Exchangeable Notes On October 2, 2017, IAC FinanceCo, Inc., a direct, wholly-owned subsidiary of the Company, issued $517.5 million aggregate principal amount of its 0.875% Exchangeable Senior Notes (the "Exchangeable Notes"). The Exchangeable Notes are guaranteed by the Company. Each $1,000 of principal of the Exchangeable Notes is exchangeable for 6.5713 shares of the Company's common stock, which is equivalent to an exchange price of approximately $152.18 per share, subject to adjustment upon the occurrence of specified events. Upon exchange, the Company has the right to settle the principal amount of Exchangeable Notes with any of the three following alternatives: (1) shares of our common stock, (2) cash or (3) a combination of cash and shares of our common stock. The Exchangeable Notes are exchangeable at any time prior to the close of business on the business day immediately preceding July 1, 2022 only under the following circumstances: (1) during any calendar quarter (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days during the period of 30 consecutive trading days during the immediately preceding calendar quarter is greater than or equal to 130% of the exchange price on each applicable trading day, which occurred in the third quarter of 2018; (2) during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the exchange rate on each such trading day; (3) if the issuer calls the notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date; or (4) upon the occurrence of specified corporate events as further described under the indenture governing the Exchangeable Notes. On or after July 1, 2022 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may exchange all or any portion of their Exchangeable Notes regardless of the foregoing conditions. A portion of the net proceeds from the sale of the Exchangeable Notes of $499.5 million , after deducting fees and expenses, was used to pay the net premium of $50.7 million on the Exchangeable Note Hedge and Warrants (defined below). We separately account for the debt and the equity components of the Exchangeable Notes. Accordingly, the Company recorded a debt discount and corresponding increase to additional paid-in capital of $70.4 million , which is the fair value attributed to the exchange feature or equity component of the debt, on the date of issuance. The Company is amortizing the debt discount utilizing the effective interest method over the life of the Exchangeable Notes which increases the effective interest rate from its coupon rate of 0.875% to 3.88% . Transaction costs of $18.0 million were allocated between the liability and equity components. In connection with the debt offering, the Company purchased call options allowing the Company to purchase initially (subject to adjustment upon the occurrence of specified events) the entire 3.4 million shares that would be issuable upon the exchange of the Exchangeable Notes at approximately $152.18 per share (the "Exchangeable Note Hedge"), and sold warrants allowing the holder to purchase initially (subject to adjustment upon the occurrence of specified events) 3.4 million shares at $229.70 per share (the "Warrants"). The if-converted value of the Exchangeable Notes exceeds its principal amount by $105.0 million based on the Company's stock price on December 31, 2018 . The Exchangeable Note Hedge is expected to reduce the potential dilutive effect on the Company's common stock upon any exchange of notes and/or offset any cash payment IAC FinanceCo, Inc. is required to make in excess of the principal amount of the exchanged notes. The Warrants have a dilutive effect on the Company's common stock to the extent that the market price per share of the Company common stock exceeds the strike price of the Warrants. The cost of the Exchangeable Note Hedge was $74.4 million , which was recorded as a reduction to additional paid-in capital. The aggregate proceeds from the issuance of the Warrant were $23.6 million , which was recorded as an increase to additional paid-in capital. For the years ended December 31, 2018 and 2017 , the Company incurred interest expense of $21.2 million and $5.2 million , which includes amortization of original issue discount of $13.1 million and $3.2 million , and debt issuance costs of $3.5 million and $0.9 million , respectively. As of December 31, 2018 and 2017 , the unamortized discount is $54.0 million and $67.2 million , resulting in a net carrying value of the liability component of $463.5 million and $450.3 million , respectively. IAC Senior Notes The 4.75% Senior Notes were issued by IAC on December 21, 2012. These Notes are unconditionally guaranteed by certain of our wholly-owned domestic subsidiaries, which are designated as guarantor subsidiaries. See " Note 19—Guarantor and Non-Guarantor Financial Information " for financial information relating to guarantor and non-guarantor subsidiaries. The 4.75% Senior Notes may be redeemed at redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed during the twelve-month period beginning on December 15 of the years indicated below: Year Percentage 2018 101.583 % 2019 100.792 % 2020 and thereafter 100.000 % IAC Credit Facility On November 5, 2018, the IAC Credit Facility, under which IAC Group, LLC, a direct, wholly-owned subsidiary of the Company is the borrower, was amended and restated, reducing the facility size from $300 million to $250 million , and now expires on November 5, 2023. At December 31, 2018 and 2017 , there were no outstanding borrowings under the IAC Credit Facility. The annual commitment fee on undrawn funds is based on the consolidated net leverage ratio (as defined in the agreement) most recently reported, and is 20 basis points and 25 basis points at December 31, 2018 and 2017 , respectively. Borrowings under the IAC Credit Facility bear interest, at the Company's option, at a base rate or LIBOR, in each case, plus an applicable margin, which is determined by reference to a pricing grid based on the Company's consolidated net leverage ratio. The terms of the IAC Credit Facility require that the Company maintains a consolidated net leverage ratio of not more than 3.25 to 1.0 before the date on which the Company no longer holds majority of the outstanding voting stock of each of ANGI and MTCH ("Trigger Date") and no greater than 2.75 to 1.0 on or after the Trigger Date. The terms of the IAC Credit Facility also restrict our ability to incur additional indebtedness. Borrowings under the IAC Credit Facility are unconditionally guaranteed by substantially the same domestic subsidiaries that guarantee the 4.75% Senior Notes and are also secured by the stock of certain of our domestic and foreign subsidiaries, which includes MTCH and ANGI. The 4.75% Senior Notes are subordinate to the outstanding borrowings under the IAC Credit Facility to the extent of the value of the assets securing such borrowings. Long-term debt maturities: Years Ending December 31, (In thousands) 2019 $ 13,750 2020 13,750 2021 13,750 2022 1,004,489 2023 452,500 2024 400,000 2027 450,000 Total 2,348,239 Less: current portion of long-term debt 13,750 Less: unamortized original issue discount 61,377 Less: unamortized debt issuance costs 27,564 Total long-term debt, net $ 2,245,548

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY Description of Common Stock and Class B Convertible Common Stock Except as described herein, shares of IAC common stock and IAC Class B common stock are identical. Each holder of shares of IAC common stock and IAC Class B common stock vote together as a single class with respect to matters that may be submitted to a vote or for the consent of IAC's shareholders generally, including the election of directors. In connection with any such vote, each holder of IAC common stock is entitled to one vote for each share of IAC common stock held and each holder of IAC Class B common stock is entitled to ten votes for each share of IAC Class B common stock held. Notwithstanding the foregoing, the holders of shares of IAC common stock, acting as a single class, are entitled to elect 25% of the total number of IAC's directors, and, in the event that 25% of the total number of directors shall result in a fraction of a director, then the holders of shares of IAC common stock, acting as a single class, are entitled to elect the next higher whole number of IAC's directors. In addition, Delaware law requires that certain matters be approved by the holders of shares of IAC common stock or holders of IAC Class B common stock voting as a separate class. Shares of IAC Class B common stock are convertible into shares of IAC common stock at the option of the holder thereof, at any time, on a share-for-share basis. Such conversion ratio will in all events be equitably preserved in the event of any recapitalization of IAC by means of a stock dividend on, or a stock split or combination of, outstanding shares of IAC common stock or IAC Class B common stock, or in the event of any merger, consolidation or other reorganization of IAC with another corporation. Upon the conversion of shares of IAC Class B common stock into shares of IAC common stock, those shares of IAC Class B common stock will be retired and will not be subject to reissue. Shares of IAC common stock are not convertible into shares of IAC Class B common stock. The holders of shares of IAC common stock and the holders of shares of IAC Class B common stock are entitled to receive, share for share, such dividends as may be declared by IAC's Board of Directors out of funds legally available therefor. In the event of a liquidation, dissolution, distribution of assets or winding-up of IAC, the holders of shares of IAC common stock and the holders of shares of IAC Class B common stock are entitled to receive, share for share, all the assets of IAC available for distribution to its stockholders, after the rights of the holders of any IAC preferred stock have been satisfied. Reserved Common Shares In connection with equity compensation plans, the Exchangeable Notes and warrants, 28.0 million shares of IAC common stock are reserved at December 31, 2018 . Warrants and Exchangeable Notes At December 31, 2018 and 2017, warrants to acquire initially (subject to adjustment upon the occurrence of specified events) 3.4 million shares of IAC common stock at $229.70 per share were outstanding. The warrants were issued in connection with the issuance of the Exchangeable Notes on October 2, 2017 for aggregate proceeds of $23.6 million . During the years ended December 31, 2018 and 2017, no warrants were exercised and no Exchangeable Notes were exchanged. See " Note 7—Long-term Debt " for additional information on the Exchangeable Notes. Common Stock Repurchases During the years ended December 31, 2018 , 2017 and 2016 , the Company repurchased 0.5 million , 0.7 million and 6.3 million shares of IAC common stock for aggregate consideration, on a trade date basis, of $82.9 million , $50.1 million and $315.3 million , respectively. On May 3, 2016, IAC's Board of Directors authorized the repurchase of an additional 10.0 million shares of IAC common stock. At December 31, 2018 , the Company has approximately 8.0 million shares remaining in its share repurchase authorization.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE LOSS	ACCUMULATED OTHER COMPREHENSIVE LOSS The following tables present the components of accumulated other comprehensive (loss) income and items reclassified out of accumulated other comprehensive loss into earnings: Year Ended December 31, 2018 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive Loss (In thousands) Balance at January 1 $ (103,568 ) $ — $ (103,568 ) Other comprehensive (loss) income before reclassifications (25,106 ) 4 (25,102 ) Amounts reclassified to earnings (52 ) — (52 ) Net current period other comprehensive (loss) income (25,158 ) 4 (25,154 ) Balance at December 31 $ (128,726 ) $ 4 $ (128,722 ) Year Ended December 31, 2017 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive (Loss) Income (In thousands) Balance at January 1 $ (170,149 ) $ 4,026 $ (166,123 ) Other comprehensive income before reclassifications 65,908 7 65,915 Amounts reclassified to earnings 673 (4,033 ) (3,360 ) Net current period other comprehensive income (loss) 66,581 (4,026 ) 62,555 Balance at December 31 $ (103,568 ) $ — $ (103,568 ) Year Ended December 31, 2016 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive (Loss) Income (In thousands) Balance at January 1 $ (154,645 ) $ 2,542 $ (152,103 ) Other comprehensive (loss) income before reclassifications, net of tax benefit of $0.7 million related to unrealized losses on available-for-sale securities (46,943 ) 4,855 (42,088 ) Amounts reclassified to earnings 9,850 (2,913 ) 6,937 Net current period other comprehensive (loss) income (37,093 ) 1,942 (35,151 ) Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO 21,589 (458 ) 21,131 Balance at December 31 $ (170,149 ) $ 4,026 $ (166,123 ) The amounts reclassified out of foreign currency translation adjustment into earnings for the years ended December 31, 2018, 2017 and 2016 relate to the liquidation of international subsidiaries. The amounts reclassified out of unrealized gains on available-for-sale securities into earnings for the years ended December 31, 2017 and 2016, include a tax benefit of $3.8 million and a tax provision of $0.2 million , respectively.

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	EARNINGS (LOSS) PER SHARE The following table sets forth the computation of basic and diluted earnings (loss) per share attributable to IAC shareholders: Years Ended December 31, 2018 2017 2016 Basic Diluted Basic Diluted Basic Diluted (In thousands, except per share data) Numerator: Net earnings (loss) $ 757,747 $ 757,747 $ 358,008 $ 358,008 $ (16,151 ) $ (16,151 ) Net earnings attributable to noncontrolling interests (130,786 ) (130,786 ) (53,084 ) (53,084 ) (25,129 ) (25,129 ) Impact from public subsidiaries' dilutive securities (a)(b) — (25,228 ) — (33,531 ) — — Net earnings (loss) attributable to IAC shareholders $ 626,961 $ 601,733 $ 304,924 $ 271,393 $ (41,280 ) $ (41,280 ) Denominator: Weighted average basic shares outstanding 83,407 83,407 80,089 80,089 80,045 80,045 Dilutive securities (a) (b) (c) (d) (e) (f) (g) — 7,915 — 5,221 — — Denominator for earnings per share—weighted average shares (a) (b) (c) (d) (e) (f) (g) 83,407 91,322 80,089 85,310 80,045 80,045 Earnings (loss) per share attributable to IAC shareholders: Earnings (loss) per share $ 7.52 $ 6.59 $ 3.81 $ 3.18 $ (0.52 ) $ (0.52 ) __________________________________________________________________ (a) For the year ended December 31, 2018 , it is more dilutive for IAC to settle certain MTCH equity awards. For the years ended December 31, 2017 and 2016, it is more dilutive for MTCH to settle certain MTCH equity awards. (b) For the years ended December 31, 2018 and 2017, it is more dilutive for IAC to settle certain ANGI equity awards. The impact on earnings of ANGI dilutive securities is not applicable for periods prior to the Combination. (c) If the effect is dilutive, weighted average common shares outstanding include the incremental shares that would be issued upon the assumed exercise of stock options, warrants and subsidiary denominated equity, exchange of the Company's Exchangeable Notes and vesting of restricted stock units ("RSUs"). For the years ended December 31, 2018 and 2017, 3.5 million and 6.9 million potentially dilutive securities, respectively, are excluded from the calculation of diluted earnings per share because their inclusion would have been anti-dilutive. (d) For the year ended December 31, 2016, the Company had a loss from operations; therefore, approximately 11.3 million potentially dilutive securities were excluded from computing dilutive earnings per share because the impact would have been anti-dilutive. Accordingly, the weighted average basic shares outstanding were used to compute all earnings per share amounts. (e) Market-based awards and performance-based stock units ("PSUs") are considered contingently issuable shares. Shares issuable upon exercise or vesting of market-based awards and PSUs are included in the denominator for earnings per share if (i) the applicable market or performance condition(s) has been met and (ii) the inclusion of the market-based awards and PSUs is dilutive for the respective reporting periods. For both the years ended December 31, 2018 and 2017, 0.1 million shares underlying market-based awards and PSUs were excluded from the calculation of diluted earnings per share because the market or performance conditions had not been met. (f) It is the Company's intention to settle the Exchangeable Notes through a combination of cash, equal to the face amount of the notes, and shares; therefore, the Exchangeable Notes are only dilutive for periods during which the average price of IAC common stock exceeds the approximate $152.18 per share exchange price per $1,000 principal amount of the Exchangeable Notes. For the year ended December 31, 2018, the average price of IAC common stock exceeded $152.18 and the dilutive impact of the Exchangeable Notes was 0.3 million shares. For the year ended December 31, 2017, the Exchangeable Notes were anti-dilutive. (g) See " Note 11—Stock-based Compensation " for additional information on equity instruments denominated in the shares of certain subsidiaries.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION IAC currently has two active plans under which awards have been granted. These plans cover stock options to acquire shares of IAC common stock, RSUs and PSUs, as well as provide for the future grant of these and other equity awards. These plans authorize the Company to grant awards to its employees, officers, directors and consultants. At December 31, 2018 , there are 11.5 million shares available for grant under the plans. The plans were adopted in 2013 and 2018, have a stated term of ten years , and provide that the exercise price of stock options granted will not be less than the market price of the Company's common stock on the grant date. The plans do not specify grant dates or vesting schedules of awards as those determinations have been delegated to the Compensation and Human Resources Committee of IAC's Board of Directors (the "Committee"). Each grant agreement reflects the vesting schedule for that particular grant as determined by the Committee. Broad-based stock option awards issued to date have generally vested in equal annual installments over a four -year period and RSU awards currently outstanding generally vest in three 33% installments over a three -year period, in each case, from the grant date. PSU awards currently outstanding cliff-vest after a three -year period from the date of grant. The amount of stock-based compensation expense recognized in the consolidated statement of operations is net of estimated forfeitures, as the expense recorded is based on awards that are ultimately expected to vest. The forfeiture rate is estimated at the grant date based on historical experience and revised, if necessary, in subsequent periods if actual forfeitures differ from the estimated rate. At December 31, 2018 , there is $326.0 million of unrecognized compensation cost, net of estimated forfeitures, related to all equity-based awards, which is expected to be recognized over a weighted average period of approximately 2.3 years. The total income tax benefit recognized in the accompanying consolidated statement of operations for the years ended December 31, 2018 , 2017 and 2016 related to all stock-based compensation is $189.0 million , $423.0 million and $34.8 million , respectively. The increase in total income tax benefit recognized in the consolidated statement of operations during 2017 relative to 2016 is due to the adoption of ASU 2016-09, effective January 1, 2017, which required the recognition of excess tax benefits attributable to stock-based compensation to be included as a component of the provision for income taxes rather than recognized in equity. The aggregate income tax benefit recognized related solely to stock options for the years ended December 31, 2018, 2017 and 2016 , including the portion recognized as a component of equity in 2016 is $169.0 million , $411.6 million , and $63.4 million , respectively. As the Company is currently in an NOL position, there will be some delay in the timing of the realization of the cash benefit of the income tax deductions related to stock-based compensation because it will be dependent upon the amount and timing of future taxable income and the timing of estimated income tax payments. IAC Stock Options Stock options outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows: December 31, 2018 Shares Weighted Weighted Aggregate (Shares and intrinsic value in thousands) Options outstanding at January 1, 2018 6,586 $ 60.57 Granted 80 152.53 Exercised (774 ) 52.56 Forfeited (72 ) 57.52 Expired (6 ) 19.51 Options outstanding at December 31, 2018 5,814 $ 62.97 6.1 $ 698,128 Options exercisable 3,592 $ 59.64 5.3 $ 443,293 The aggregate intrinsic value in the table above represents the difference between IAC's closing stock price on the last trading day of 2018 and the exercise price, multiplied by the number of in-the-money options that would have been exercised had all option holders exercised their options on December 31, 2018 . The total intrinsic value of stock options exercised during the years ended December 31, 2018 , 2017 and 2016 is $83.7 million , $164.6 million and $17.1 million , respectively. The following table summarizes the information about stock options outstanding and exercisable at December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Outstanding at Weighted- Weighted- Exercisable at Weighted- Weighted- (Shares in thousands) $20.01 to $30.00 30 1.1 $ 21.60 30 1.1 $ 21.60 $30.01 to $40.00 389 2.3 32.30 389 2.3 32.30 $40.01 to $50.00 1,541 5.8 43.35 961 5.0 44.26 $50.01 to $60.00 246 3.2 59.85 244 3.2 59.86 $60.01 to $70.00 1,173 6.3 65.27 767 6.0 65.62 $70.01 to $80.00 1,840 7.4 75.33 822 6.8 74.72 $80.01 to $90.00 500 6.3 84.31 375 6.3 84.31 Greater than $90.01 95 9.1 148.30 4 8.9 125.08 5,814 6.1 62.97 3,592 5.3 59.64 The fair value of stock option awards, with the exception of market-based awards, is estimated on the grant date using the Black-Scholes option pricing model. The Black-Scholes option pricing model incorporates various assumptions, including expected volatility and expected term. During 2018 , 2017 and 2016 , expected stock price volatilities were estimated based on the Company's historical volatility. The risk-free interest rates are based on U.S. Treasuries with comparable terms as the awards, in effect at the grant date. Expected term is based upon the historical exercise behavior of our employees and the dividend yields are based on IAC's historical dividend payments. The following are the weighted average assumptions used in the Black-Scholes option pricing model: Years Ended December 31, 2018 2017 2016 Expected volatility 27 % 29 % 29 % Risk-free interest rate 2.7 % 2.0 % 1.2 % Expected term 6.2 years 5.2 years 4.8 years Dividend yield — % — % — % During 2018, the Company granted market-based stock options that only vest if the price of IAC common stock exceeds the relevant price threshold for a twenty -day consecutive period and the service requirement is met. The market-based vesting condition was achieved in the fourth quarter of 2018. The service requirement provides that this award vests in two installments, the first 50% in 2021 and the second 50% in 2022. The grant date fair value of the market-based award was estimated using a lattice model that incorporates a Monte Carlo simulation of IAC's stock price. The inputs used to fair value this award included an expected volatility of 29% , risk-free interest rate of 2.8% and a zero -dividend yield. The expected term of 1.8 years for this award was derived from the output of the option valuation model. Expense is recognized over the longer of the vesting period of each of the two installments or the expected term. Approximately less than 0.1 million , 1.2 million and 1.7 million stock options were granted by the Company during the years ended December 31, 2018 , 2017 and 2016 , respectively. The weighted average fair value of stock options granted during the years ended December 31, 2018 , 2017 and 2016 are $53.94 , $22.94 and $12.34 , respectively. Cash received from stock option exercises for the years ended December 31, 2018 , 2017 and 2016 was $41.7 million , $82.4 million and $25.8 million , respectively. The Company has historically settled its stock options on a gross basis. Assuming all stock options outstanding on December 31, 2018 were net settled on that date, the Company would have remitted $349.1 million (of which $221.6 million is related to vested stock options and $127.4 million is related to unvested stock options) in cash for withholding taxes (assuming a 50% withholding rate). IAC Restricted Stock Units and Performance-based Stock Units RSUs and PSUs are awards in the form of phantom shares or units denominated in a hypothetical equivalent number of shares of IAC common stock and with the value of each RSU and PSU equal to the fair value of IAC common stock at the date of grant. Each RSU and PSU grant is subject to service-based vesting, where a specific period of continued employment must pass before an award vests. PSUs also include performance-based vesting, where certain performance targets set at the time of grant must be achieved before an award vests. For RSU grants, the expense is measured at the grant date as the fair value of IAC common stock and expensed as stock-based compensation over the vesting term. For PSU grants, the expense is measured at the grant date as the fair value of IAC common stock and expensed as stock-based compensation over the vesting term if the performance targets are considered probable of being achieved. Unvested RSUs and PSUs outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows: RSUs PSUs Number Weighted Number Weighted (Shares in thousands) Unvested at January 1, 2018 360 $ 80.81 130 $ 76.00 Granted 153 183.33 30 152.53 Vested (49 ) 78.54 — — Forfeited (5 ) 98.81 (17 ) 76.00 Unvested at December 31, 2018 459 $ 115.12 143 $ 92.02 The weighted average fair value of RSUs and PSUs granted during the years ended December 31, 2018 , 2017 and 2016 based on market prices of IAC's common stock on the grant date was $178.29 , $90.04 and $46.92 , respectively. The total fair value of RSUs and PSUs that vested during the years ended December 31, 2018 , 2017 and 2016 was $8.9 million , $32.5 million and $13.5 million , respectively. Equity Instruments Denominated in the Shares of Certain Subsidiaries Non-publicly-traded Subsidiaries The following description excludes awards denominated in the shares of the Company's publicly-traded subsidiaries, MTCH and ANGI. MTCH and ANGI stock-based awards are issued pursuant to their respective stock incentive plans. The Company has granted stock settled stock appreciation rights denominated in the equity of certain non-publicly traded subsidiaries to employees and management of those subsidiaries. These equity awards vest over a period of years or upon the occurrence of certain prescribed events. The value of the stock settled stock appreciation rights is tied to the value of the common stock of these subsidiaries. Accordingly, these interests only have value to the extent the relevant business appreciates in value above the initial value utilized to determine the exercise price. These interests can have significant value in the event of significant appreciation. The fair value of these interest is generally determined by negotiation or arbitration, when settled; which will occur at various dates through 2025 . These equity awards are settled on a net basis, with the award holder entitled to receive a payment in IAC common shares equal to the intrinsic value of the award at exercise less an amount equal to the required cash tax withholding payment. The number of IAC common shares ultimately needed to settle these awards may vary significantly from the estimated number below as a result of both movements in our stock price and a determination of fair value of the relevant subsidiary that is different than our estimate. The expense associated with these equity awards is initially measured at fair value at the grant date and is expensed as stock-based compensation over the vesting term. The number of IAC common shares that would be required to settle these interests at current estimated fair values, including vested and unvested interests, at December 31, 2018 is 0.1 million shares. Withholding taxes, which will be paid by the Company on behalf of the employees upon exercise, would have been $16.0 million at December 31, 2018 , assuming a 50% withholding rate. MTCH MTCH currently settles substantially all equity awards on a net basis. Assuming all MTCH equity awards outstanding on December 31, 2018 were net settled on that date, MTCH would have issued 9.7 million common shares (of which 1.7 million is related to vested shares and 8.0 million is related to unvested shares) and would have remitted $416.2 million (of which $75.0 million is related to vested shares and $341.2 million is related to unvested shares) in cash for withholding taxes (assuming a 50% withholding rate). If MTCH decided to issue a sufficient number of shares to cover the $416.2 million employee withholding tax obligation, 9.7 million additional shares would be issued by MTCH. Following the completion of the MTCH IPO, equity awards that related to certain subsidiaries (principally Tinder, Inc.) of MTCH were settleable, at IAC's election, in shares of IAC common stock or MTCH common stock. Pursuant to the Employee Matters Agreement between IAC and MTCH, to the extent shares of IAC common stock are issued in settlement of these awards, MTCH reimburses IAC for the cost of those shares in cash or by issuing IAC shares of MTCH common stock. In July 2017, Tinder was merged into MTCH and as a result, all Tinder denominated equity awards were converted into MTCH tandem stock options ("Tandem Awards"). All of the MTCH Tandem Awards exercised during 2018 and 2017 were exercised on a net basis and were settled in IAC common shares; the Company issued 0.7 million and 2.0 million shares, respectively, of its common stock to settle these awards and MTCH issued 2.5 million and 11.3 million shares, respectively, of its common stock to IAC as reimbursement. Assuming all vested and unvested Tandem Awards outstanding on December 31, 2018 were exercised on that date and settled using IAC stock, 0.3 million IAC common shares would have been issued in settlement and MTCH would have issued 1.4 million shares, which is included in the amount above, to IAC as reimbursement. During 2017, MTCH also purchased certain fully vested Tandem Awards, and made cash payments of approximately $520 million to cover both the withholding taxes paid on behalf of employees exercising these converted awards and the purchase of certain fully vested awards. During 2016 , the Company granted a nominal amount of IAC denominated market-based awards to certain MTCH employees. The number of awards that ultimately vest is dependent upon MTCH's stock price. The grant date fair value of each market-based award is estimated using a lattice model that incorporates a Monte Carlo simulation of MTCH's stock price. Each market-based award is subject to service-based vesting, where a specific period of continued employment must pass before an award vests. Some of the market-based awards contain performance targets set at the time of grant that must be achieved before an award vests. ANGI In connection with the Combination, previously issued stock appreciation rights related to the common stock of HomeAdvisor (US) were converted into ANGI stock appreciation rights that are settleable, at ANGI's option, on a net basis with ANGI remitting withholding taxes on behalf of the employee or on a gross basis with ANGI issuing a sufficient number of Class A shares to cover the withholding taxes. In addition, at IAC's option, these awards can be settled in either Class A shares of ANGI or shares of IAC common stock. If settled in IAC common stock, ANGI reimburses IAC in either cash or through the issuance of Class A shares to IAC. Assuming all of the stock appreciation rights outstanding on December 31, 2018 were net settled on that date using IAC stock, 1.1 million IAC common shares would have been issued in settlement and IAC would have been issued 12.8 million shares of ANGI Class A stock and ANGI would have remitted $205.9 million in cash for withholding taxes (assuming a 50% withholding rate). If ANGI decided to issue a sufficient number of shares to cover the $205.9 million employee withholding tax obligation, 12.8 million additional Class A shares would be issued by ANGI. ANGI's cash withholding obligation on all other ANGI net settled awards outstanding on December 31, 2018 is $36.5 million (assuming a 50% withholding rate), which is the equivalent of 2.3 million shares. Prior to the Combination in 2017, the Company issued a number of IAC denominated PSUs to certain ANGI employees. Vesting of the PSUs is contingent upon ANGI's performance. Assuming all of the PSUs outstanding on December 31, 2018 were net settled on that date using IAC stock, 0.1 million IAC common shares would have been issued in settlement and IAC would have been issued 0.6 million shares of ANGI Class A stock and ANGI would have remitted $10.4 million in cash for withholding taxes (assuming a 50% withholding rate). Modification of awards During 2018, the Company modified certain equity awards and recognized modification charges of $7.9 million . In addition, in connection with the ANGI chief executive officer transition during the fourth quarter of 2018, ANGI accelerated $3.9 million of expense into 2018 from 2019. In connection with the Combination, the previously issued HomeAdvisor (US) stock appreciation rights were converted into ANGI equity awards resulting in a modification charge of $217.7 million of which $56.9 million and $93.4 million were recognized as stock-based compensation expense in the years ended December 31, 2018 and 2017, respectively, and the remaining charge will be recognized over the vesting period of the modified awards. During the second quarter of 2017, the Company modified certain HomeAdvisor (US) denominated equity awards and recognized a modification charge of $6.6 million . During 2016, the Company modified certain subsidiary denominated equity awards resulting in a modification charge of $7.3 million (subsequently reduced to $7.1 million due to forfeitures) of which $0.1 million , $0.7 million and $6.3 million were recognized as stock-based compensation in the years ended December 31, 2018, 2017 and 2016, respectively. During 2014, the Company granted an equity award denominated in shares of a subsidiary of the Company to a non-employee, which was marked to market each reporting period. In the third quarter of 2016, MTCH settled the vested portion of the award for cash of $13.4 million . In the third quarter of 2017, the award was modified and MTCH settled the remaining portion of the award for cash of $33.9 million .

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION . The overall concept that IAC employs in determining its operating segments is to present the financial information in a manner consistent with: how the chief operating decision maker views the businesses; how the businesses are organized as to segment management; and the focus of the businesses with regards to the types of services or products offered or the target market. Operating segments are combined for reporting purposes if they meet certain aggregation criteria, which principally relate to the similarity of their economic characteristics or, in the case of the Emerging & Other reportable segment, do not meet the quantitative thresholds that require presentation as separate reportable segments. The following table presents revenue by reportable segment: Years Ended December 31, 2018 2017 2016 (In thousands) Revenue: Match Group $ 1,729,850 $ 1,330,661 $ 1,118,110 ANGI Homeservices 1,132,241 736,386 498,890 Vimeo 159,641 103,332 78,805 Dotdash 130,991 90,890 77,913 Applications 582,287 577,998 604,140 Emerging & Other 528,250 468,589 762,609 Inter-segment elimination (368 ) (617 ) (585 ) Total $ 4,262,892 $ 3,307,239 $ 3,139,882 The following table presents the revenue of the Company's segments disaggregated by type of service: Years Ended December 31, 2018 2017 2016 (In thousands) Match Group Direct revenue: North America $ 902,478 $ 741,334 $ 673,944 International 774,693 539,915 393,420 Direct revenue 1,677,171 1,281,249 1,067,364 Indirect revenue (principally advertising revenue) 52,679 49,412 50,746 Total Match Group revenue $ 1,729,850 $ 1,330,661 $ 1,118,110 Supplemental information on Direct revenue Tinder $ 805,316 $ 403,216 $ 168,522 Other brands 871,855 878,033 898,842 Total Direct revenue $ 1,677,171 $ 1,281,249 $ 1,067,364 ANGI Homeservices Marketplace: Consumer connection revenue $ 704,341 $ 521,481 $ 382,466 Membership subscription revenue 66,214 56,135 43,573 Other revenue 3,940 3,798 2,827 Marketplace revenue 774,495 581,414 428,866 Advertising and other revenue 287,676 97,483 32,981 North America 1,062,171 678,897 461,847 Consumer connection revenue 50,913 40,009 28,124 Membership subscription revenue 17,362 16,596 7,936 Advertising and other revenue 1,795 884 983 Europe 70,070 57,489 37,043 Total ANGI Homeservices revenue $ 1,132,241 $ 736,386 $ 498,890 Vimeo Platform revenue $ 146,665 $ 99,650 $ 78,805 Hardware revenue 12,976 3,682 — Years Ended December 31, 2018 2017 2016 (In thousands) Total Vimeo revenue $ 159,641 $ 103,332 $ 78,805 Dotdash Advertising revenue $ 113,014 $ 81,948 $ 76,099 Affiliate commerce commission revenue 14,458 7,372 1,685 Other revenue 3,519 1,570 129 Total Dotdash revenue $ 130,991 $ 90,890 $ 77,913 Applications Desktop Advertising revenue: Google advertising revenue $ 426,964 $ 480,774 $ 523,335 Other 10,992 6,762 10,037 Advertising revenue 437,956 487,536 533,372 Subscription and other revenue 20,815 34,613 29,943 Total Desktop 458,771 522,149 563,315 Mosaic Group Subscription and other revenue 104,975 27,980 21,787 Advertising revenue 18,541 27,869 19,038 Total Mosaic Group 123,516 55,849 40,825 Total Applications revenue $ 582,287 $ 577,998 $ 604,140 Emerging & Other Advertising revenue: Google advertising revenue $ 357,752 $ 225,576 $ 269,192 Other 66,733 53,911 75,008 Advertising revenue 424,485 279,487 344,200 Other revenue 103,765 169,497 160,329 Test preparation revenue — 19,605 86,517 Product revenue — — 171,563 Total Emerging & Other revenue $ 528,250 $ 468,589 $ 762,609 Revenue by geography is based on where the customer is located. Geographic information about revenue and long-lived assets is presented below: Years Ended December 31, 2018 2017 2016 (In thousands) Revenue United States $ 2,824,928 $ 2,323,050 $ 2,318,976 All other countries 1,437,964 984,189 820,906 Total $ 4,262,892 $ 3,307,239 $ 3,139,882 December 31, 2018 2017 (In thousands) Long-lived assets (excluding goodwill and intangible assets) United States $ 289,756 $ 286,541 All other countries 29,044 28,629 Total $ 318,800 $ 315,170 The following tables present operating income (loss) and Adjusted EBITDA by reportable segment: Years Ended December 31, 2018 2017 2016 (In thousands) Operating Income (Loss): Match Group $ 553,294 $ 360,517 $ 315,549 ANGI Homeservices 63,906 (149,176 ) 25,363 Vimeo (35,594 ) (27,328 ) (25,350 ) Dotdash 18,778 (15,694 ) (248,705 ) Applications 94,834 130,176 109,663 Emerging & Other 29,964 17,412 (99,696 ) Corporate (160,043 ) (127,441 ) (109,449 ) Total $ 565,139 $ 188,466 $ (32,625 ) Years Ended December 31, 2018 2017 2016 (In thousands) Adjusted EBITDA: (a) Match Group $ 653,931 $ 468,941 $ 403,380 ANGI Homeservices $ 247,506 $ 37,858 $ 45,851 Vimeo $ (28,045 ) $ (23,607 ) $ (20,281 ) Dotdash $ 21,384 $ (2,763 ) $ (16,846 ) Applications $ 131,837 $ 136,757 $ 132,276 Emerging & Other $ 36,178 $ 25,862 $ 10,111 Corporate $ (74,017 ) $ (67,755 ) $ (53,272 ) _______________________________________________________________________________ (a) The Company's primary financial measure is Adjusted EBITDA, which is defined as operating income excluding: (1) stock-based compensation expense; (2) depreciation; and (3) acquisition-related items consisting of (i) amortization of intangible assets and impairments of goodwill and intangible assets, if applicable, and (ii) gains and losses recognized on changes in the fair value of contingent consideration arrangements. The Company believes this measure is useful for analysts and investors as this measure allows a more meaningful comparison between our performance and that of our competitors. Moreover, our management uses this measure internally to evaluate the performance of our businesses, and this measure is one of the primary metrics on which our internal budgets are based and by which management is compensated. The above items are excluded from our Adjusted EBITDA measure because these items are non-cash in nature. Adjusted EBITDA has certain limitations in that it does not take into account the impact to IAC's statement of operations of certain expenses. The following tables reconcile operating income (loss) for the Company's reportable segments and net earnings attributable to IAC shareholders to Adjusted EBITDA: Year Ended December 31, 2018 Operating Stock-Based Depreciation Amortization Acquisition-related Contingent Consideration Fair Value Adjustments Adjusted EBITDA (In thousands) Match Group $ 553,294 $ 66,031 $ 32,968 $ 1,318 $ 320 $ 653,931 ANGI Homeservices 63,906 $ 97,078 $ 24,310 $ 62,212 $ — $ 247,506 Vimeo (35,594 ) $ — $ 1,200 $ 6,349 $ — $ (28,045 ) Dotdash 18,778 $ — $ 969 $ 1,637 $ — $ 21,384 Applications 94,834 $ — $ 2,601 $ 33,266 $ 1,136 $ 131,837 Emerging & Other 29,964 $ 919 $ 1,678 $ 3,617 $ — $ 36,178 Corporate (160,043 ) $ 74,392 $ 11,634 $ — $ — $ (74,017 ) Total 565,139 Interest expense (109,327 ) Other income, net 305,746 Earnings before income taxes 761,558 Income tax provision (3,811 ) Net earnings 757,747 Net earnings attributable to noncontrolling interests (130,786 ) Net earnings attributable to IAC shareholders $ 626,961 Year Ended December 31, 2017 Operating Income (Loss) Stock-Based Compensation Expense Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Adjusted EBITDA (In thousands) Match Group $ 360,517 $ 69,090 $ 32,613 $ 1,468 $ 5,253 $ 468,941 ANGI Homeservices (149,176 ) $ 149,230 $ 14,543 $ 23,261 $ — $ 37,858 Vimeo (27,328 ) $ — $ 1,408 $ 2,313 $ — $ (23,607 ) Dotdash (15,694 ) $ — $ 2,255 $ 10,676 $ — $ (2,763 ) Applications 130,176 $ — $ 3,863 $ 2,170 548 — $ 136,757 Emerging & Other 17,412 $ 2,130 $ 4,065 $ 2,255 $ — $ 25,862 Corporate (127,441 ) $ 44,168 $ 15,518 $ — $ — $ (67,755 ) Total 188,466 Interest expense (105,295 ) Other expense, net (16,213 ) Earnings before income taxes 66,958 Income tax benefit 291,050 Net earnings 358,008 Net earnings attributable to noncontrolling interests (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 Year Ended December 31, 2016 Operating Income (Loss) Stock-Based Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Goodwill Impairment Adjusted EBITDA (In thousands) Match Group $ 315,549 $ 52,370 $ 27,726 $ 16,932 $ (9,197 ) $ — $ 403,380 ANGI Homeservices 25,363 $ 8,916 $ 8,419 $ 3,153 $ — $ — $ 45,851 Vimeo (25,350 ) $ — $ 1,085 $ 4,176 $ (192 ) $ — $ (20,281 ) Dotdash (248,705 ) $ — $ 2,775 $ 30,754 $ — $ 198,330 $ (16,846 ) Applications 109,663 $ — $ 5,095 $ 5,483 $ 12,035 $ — $ 132,276 Emerging & Other (99,696 ) $ 1,258 $ 12,675 $ 18,928 $ (91 ) $ 77,037 $ 10,111 Corporate (109,449 ) $ 42,276 $ 13,901 $ — $ — $ — $ (53,272 ) Total (32,625 ) Interest expense (109,110 ) Other income, net 60,650 Loss before income taxes (81,085 ) Income tax benefit 64,934 Net loss (16,151 ) Net earnings attributable to noncontrolling interests (25,129 ) Net loss attributable to IAC shareholders $ (41,280 ) The following tables reconcile segment assets to total assets by reportable segment: December 31, 2018 Segment Assets (b) Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 377,965 $ 58,351 $ 1,245,013 $ 230,684 $ 6,956 $ 1,918,969 ANGI Homeservices 497,327 70,859 892,800 171,486 132,809 1,765,281 Vimeo 33,568 1,014 77,152 — 9,442 121,176 Dotdash 39,276 3,229 — 13,500 1,514 57,519 Applications 153,781 4,867 504,892 39,463 22,447 725,450 Emerging & Other 95,858 1,638 7,002 2,971 150 107,619 Corporate (c) 1,934,943 178,842 — — — 2,113,785 Total $ 3,132,718 $ 318,800 $ 2,726,859 $ 458,104 $ 173,318 6,809,799 Add: Deferred tax assets (d) 64,786 Total Assets $ 6,874,585 December 31, 2017 Segment Assets (b) Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 467,338 $ 61,620 $ 1,247,899 $ 228,296 $ 2,049 $ 2,007,202 ANGI Homeservices 264,450 53,292 768,317 153,447 175,124 1,414,630 Vimeo 30,507 1,972 77,303 — 15,655 125,437 Dotdash 27,190 4,077 — 6,000 3,152 40,419 Applications 345,532 7,004 447,242 60,600 847 861,225 Emerging & Other 255,107 2,377 18,305 10,800 7,767 294,356 Corporate (c) 873,392 184,828 — — — 1,058,220 Total $ 2,263,516 $ 315,170 $ 2,559,066 $ 459,143 $ 204,594 5,801,489 Add: Deferred tax assets (d) 66,321 Total Assets $ 5,867,810 _____________________________________ (b) Consistent with the Company's primary metric (described in (a) above), the Company excludes, if applicable, property and equipment, goodwill and intangible assets from the measure of segment assets presented above. (c) Corporate assets consist primarily of cash and cash equivalents, marketable securities and IAC's headquarters building. (d) Total segment assets differ from total assets on a consolidated basis as a result of unallocated deferred tax assets. The following table presents capital expenditures by reportable segment: Years Ended December 31, 2018 2017 2016 (In thousands) Capital expenditures: Match Group $ 30,954 $ 28,833 $ 46,098 ANGI Homeservices 46,976 26,837 16,660 Vimeo 209 109 1,959 Dotdash 102 825 1,671 Applications 111 227 1,196 Emerging & Other 1,119 852 6,683 Corporate 6,163 17,840 3,772 Total $ 85,634 $ 75,523 $ 78,039

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Commitments The Company leases land, office space, data center facilities and equipment used in connection with its operations under various operating leases, many of which contain escalation clauses. The Company is also committed to pay a portion of the related operating expenses under certain lease agreements. These operating expenses are not included in the table below. Future minimum payments under operating lease agreements are as follows: Years Ending December 31, (In thousands) 2019 $ 38,770 2020 46,440 2021 40,998 2022 34,066 2023 30,567 Thereafter 255,563 Total $ 446,404 Expenses charged to operations under these agreements are $42.0 million , $37.9 million and $50.8 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The Company's three most significant operating leases are for IAC's headquarters in New York City that expires in 2081, ANGI's call center in New York that expires in 2028 and ANGI's headquarters in Denver, Colorado that expires in 2029, which collectively approximate 61% of the future minimum payments due under all operating lease agreements in the table above. The Company also has funding commitments that could potentially require its performance in the event of demands by third parties or contingent events as follows: Amount of Commitment Expiration Per Period Less Than 1 Year 1-3 Years 3-5 Years More Than 5 Years Total Amounts Committed (In thousands) Purchase obligations $ 40,428 $ 23,897 $ — $ — $ 64,325 Letters of credit and surety bonds 449 — — 2,272 2,721 Total commercial commitments $ 40,877 $ 23,897 $ — $ 2,272 $ 67,046 The purchase obligations principally include web hosting commitments. The letters of credit primarily support the Company's casualty insurance program. Contingencies In the ordinary course of business, the Company is a party to various lawsuits. The Company establishes reserves for specific legal matters when it determines that the likelihood of an unfavorable outcome is probable and the loss is reasonably estimable. Management has also identified certain other legal matters where we believe an unfavorable outcome is not probable and, therefore, no reserve is established. Although management currently believes that resolving claims against us, including claims where an unfavorable outcome is reasonably possible, will not have a material impact on the liquidity, results of operations, or financial condition of the Company, these matters are subject to inherent uncertainties and management's view of these matters may change in the future. The Company also evaluates other contingent matters, including income and non-income tax contingencies, to assess the likelihood of an unfavorable outcome and estimated extent of potential loss. It is possible that an unfavorable outcome of one or more of these lawsuits or other contingencies could have a material impact on the liquidity, results of operations, or financial condition of the Company. See " Note 3—Income Taxes " for additional information related to income tax contingencies. On August 14, 2018, ten then-current and former employees of Match Group, LLC or Tinder, Inc. ("Tinder"), an operating business of Match Group, filed a lawsuit in New York state court against IAC and Match Group. See Sean Rad et al. v. IAC/InterActiveCorp and Match Group, Inc. , No. 654038/2018 (Supreme Court, New York County). The complaint alleges that in 2017, the defendants: (i) wrongfully interfered with a contractually established process for the independent valuation of Tinder by certain investment banks, resulting in a substantial undervaluation of Tinder and a consequent underpayment to the plaintiffs upon exercise of their Tinder stock options, and (ii) then wrongfully merged Tinder into Match Group, thereby depriving one of the plaintiffs (Mr. Rad) of his contractual right to later valuations of Tinder on a stand-alone basis. The complaint asserts claims for breach of contract, breach of the implied covenant of good faith and fair dealing, unjust enrichment, interference with contractual relations (as against Match Group only), and interference with prospective economic advantage, and seeks compensatory damages in the amount of at least $2 billion , as well as punitive damages. On August 31, 2018, four plaintiffs who were still employed by Match Group filed a notice of discontinuance of their claims without prejudice, leaving the six former employees as the remaining plaintiffs. On October 9, 2018, the defendants filed a motion to dismiss the complaint on various grounds, including that the 2017 valuation of Tinder by the investment banks was an expert determination any challenge to which is both time-barred under applicable law and available only on narrow substantive grounds that the plaintiffs have not pleaded in their complaint. On December 17, 2018, plaintiffs filed their opposition to the motion to dismiss. On January 15, 2019, the defendants filed their reply brief. A hearing on the motion is scheduled for March 6, 2019, and discovery in the case is proceeding. IAC and Match Group believe that the allegations in this lawsuit are without merit and will continue to defend vigorously against it.

SUPPLEMENTAL CASH FLOW INFORMAT

SUPPLEMENTAL CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
SUPPLEMENTAL CASH FLOW INFORMATION	SUPPLEMENTAL CASH FLOW INFORMATION Supplemental Disclosure of Non-Cash Transactions: The Company recorded acquisition-related contingent consideration liabilities of $25.5 million and $0.2 million during the years ended December 31, 2018 and 2016 , respectively, in connection with various acquisitions. There were no acquisition-related contingent consideration liabilities recorded for the year ended December 31, 2017 . See " Note 6—Financial Instruments " for additional information on contingent consideration arrangements. On October 19, 2018, ANGI issued 8.6 million shares of its Class A common stock valued at $165.8 million in connection with the acquisition of Handy. On September 29, 2017, ANGI issued 61.3 million shares of its Class A common stock valued at $763.7 million in connection with the Combination. Supplemental Disclosure of Cash Flow Information: Years Ended December 31, 2018 2017 2016 (In thousands) Cash paid (received) during the year for: Interest $ 90,485 $ 92,461 $ 107,360 Income tax payments 45,154 35,598 69,103 Income tax refunds (33,698 ) (42,025 ) (23,877 )

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS IAC and MTCH: IAC and MTCH, in connection with MTCH's IPO, entered into the following agreements: • A Master Transaction Agreement, under which MTCH agrees to assume all of the assets and liabilities related to its business and agrees to indemnify IAC against any losses arising out of any breach by MTCH of the Master Transaction Agreement or other IPO related agreements; • An Investor Rights Agreement that provides IAC with (i) specified registration and other rights relating to shares of MTCH common stock and (ii) anti-dilution rights with respect to MTCH common stock; • An Employee Matters Agreement, which governs the respective rights, responsibilities and obligations of IAC and MTCH after the IPO with respect to a range of compensation and benefit issues; • A Tax Sharing Agreement, which governs the respective rights, responsibilities and obligations of IAC and MTCH with respect to tax liabilities and benefits, entitlement to refunds, preparation of tax returns, tax contests and other tax matters regarding U.S. federal, state, local and foreign income taxes; and • A Services Agreement, under which IAC has agreed to provide a range of services to MTCH, including, among others, (i) assistance with certain legal, finance, internal audit, treasury, information technology support, insurance and tax affairs, including assistance with certain public company reporting obligations; (ii) payroll processing services; (iii) tax compliance services; and (iv) such other services as to which IAC and MTCH may agree, and MTCH agrees to provide IAC informational technology services and such other services as to which IAC and MTCH may agree. During the years ended December 31, 2018 , 2017 and 2016 , 3.0 million , 11.9 million and 1.0 million shares, respectively, of MTCH common stock were issued to IAC pursuant to the employee matters agreement; 2.5 million , 11.3 million and 0.5 million , respectively, of which were issued as reimbursement for shares of IAC common stock issued in connection with the exercise and settlement of MTCH tandem stock options and equity awards denominated in shares of a subsidiary of MTCH, respectively; and 0.5 million , 0.6 million and 0.4 million , respectively, of which were issued as reimbursement for shares of IAC common stock issued in connection with the exercise and vesting of IAC equity awards held by MTCH employees. For the years ended December 31, 2018 , 2017 and 2016, MTCH was charged $7.6 million , $9.9 million and $11.8 million , respectively, by the Company for services rendered pursuant to a services agreement. Included in these amounts are $5.2 million , $5.1 million and $4.3 million , respectively, for leasing of office space for certain of MTCH's businesses at properties owned by IAC. These amounts were paid in full by MTCH at December 31, 2018 , 2017 and 2016 , respectively. At December 31, 2017 , MTCH had a tax receivable of $7.3 million due from the Company pursuant to the tax sharing agreement. Refunds made by the Company during 2018 and 2017 pursuant to this agreement were $7.0 million and $10.9 million , respectively. There were no outstanding receivables or payables pursuant to the tax sharing agreement as of December 31, 2018 . In December 2017, certain international subsidiaries of MTCH agreed to sell NOLs that were not expected to be utilized to an IAC subsidiary for $0.9 million . IAC and ANGI: IAC and ANGI, in connection with the Combination, entered into the following agreements: • A Contribution Agreement under which the Company separated its HomeAdvisor business from its other businesses and caused the HomeAdvisor business to be transferred to ANGI prior to the Combination. Under the Contribution Agreement, ANGI agrees to indemnify IAC against any losses arising out of any breach by ANGI of the Contribution Agreement; • An Investor Rights Agreement that provides IAC with (i) specified registration and other rights relating to shares of ANGI common stock owned by IAC; (ii) anti-dilution rights with respect to ANGI common stock; and (iii) specified board matters with respect to designation of ANGI directors; • A Services Agreement, under which IAC has agreed to provide a range of services to ANGI, including, among others, (i) assistance with certain legal, M&A, human resources, finance, risk management, internal audit and treasury functions, health and wellness, information security services and insurance and tax affairs, including assistance with certain public company and unclaimed property reporting obligations; (ii) accounting, controllership and payroll processing services; (iii) investor relations services; (iv) tax compliance services; and (iv) such other services as to which IAC and ANGI may agree. • A Tax Sharing Agreement, which governs the respective rights, responsibilities and obligations of IAC and ANGI with respect to tax matters, including taxes attributable to ANGI, entitlement to refunds, allocation of tax attributes, preparation of tax returns, certain tax elections, control of tax contests and other tax matters regarding U.S. federal, state, local and foreign income taxes; and • An Employee Matters Agreement, which governs the respective rights, responsibilities and obligations of IAC and ANGI after the closing of the Combination w ith respect to a range of compensation and benefit issues. Additionally, on September 29, 2017, the Company and ANGI entered into two intercompany notes (collectively referred to as "Intercompany Notes") to ANGI as follows: (i) a Payoff Intercompany Note, which provided the funds necessary to repay the outstanding balance under Angie's List's previously existing credit agreement, totaling $61.5 million ; and (ii) a Working Capital Intercompany Note, which provided ANGI with $15 million for working capital purposes. These Intercompany Notes were repaid on November 1, 2017, with a portion of the proceeds from the ANGI Term Loan that were received on the same date. For the years ended December 31, 2018 and for the period subsequent to the Combination through December 31, 2017, 0.9 million and 0.4 million shares, respectively, of ANGI Class B common stock were issued to IAC pursuant to the employee matters agreement as reimbursement for shares of IAC common stock issued in connection with the exercise and vesting of IAC equity awards held by ANGI employees. On October 10, 2018, IAC was issued 5.1 million shares of Class B common stock of ANGI pursuant to the post-closing adjustment provision of the Angie's List merger agreement. For the years ended December 31, 2018 and for the period subsequent to the Combination through December 31, 2017, ANGI was charged $5.7 million and $1.7 million , respectively, by the Company for services rendered pursuant to the services agreement. At December 31, 2018 and 2017 , the Company had a $0.1 million outstanding payable to ANGI and a $0.4 million receivable from ANGI, respectively, pursuant to the services agreement. In addition, ANGI had an outstanding payable due to IAC of $2.0 million at December 31, 2017 related primarily to transaction related costs incurred in connection with the Combination, which was paid in full during the first quarter of 2018. There were no comparable costs in 2018. At December 31, 2018 , ANGI had taxes payable of $12.1 million due to the Company pursuant to the tax sharing agreement. No payments were made to the Company during 2018 pursuant to this agreement. IAC and Expedia: Each of IAC and Expedia has a 50% ownership interest in two aircrafts that may be used by both companies. The Company and Expedia purchased an aircraft during the second quarter of 2017 to replace a previously owned aircraft, which was subsequently sold on February 13, 2018. The Company paid $17.4 million ( 50% of the total purchase price and refurbish costs) for its interest in the new aircraft. Members of the aircrafts' flight crews are employed by an entity in which each of the Company and Expedia has a 50% ownership interest. The Company and Expedia have agreed to share costs relating to flight crew compensation and benefits pro-rata according to each company's respective usage of the aircraft, for which they are separately billed by the entity described above. The Company and Expedia are related parties since they are under common control, given that Mr. Diller serves as Chairman and Senior Executive of both IAC and Expedia. For the years ended December 31, 2018 , 2017 and 2016 , total payments made to this entity by the Company were not material.

BENEFIT PLANS

BENEFIT PLANS	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
BENEFIT PLANS	BENEFIT PLANS IAC has a retirement savings plan in the United States that qualifies under Section 401(k) of the Internal Revenue Code. Under the IAC/InterActiveCorp Retirement Savings Plan ("the Plan"), participating employees may contribute up to 50% of their pre-tax earnings, but not more than statutory limits. IAC contributes fifty cents for each dollar a participant contributes in this plan, with a maximum contribution of 3% of a participant's eligible earnings. Matching contributions for the Plan for the years ended December 31, 2018 , 2017 and 2016 are $12.9 million , $11.1 million and $10.0 million , respectively. Matching contributions are invested in the same manner as each participant's voluntary contributions in the investment options provided under the Plan. An investment option in the Plan is IAC common stock, but neither participant nor matching contributions are required to be invested in IAC common stock. The increase in matching contributions in 2018 and 2017 are due primarily to an increase in participation in the Plan due to increases in headcount from the Combination and continued corporate growth at ANGI, MTCH, Vimeo and Dotdash. IAC also has or participates in various benefit plans, principally defined contribution plans, for its international employees. IAC's contributions for these plans for the years ended December 31, 2018 , 2017 and 2016 are $3.4 million , $2.5 million and $2.1 million , respectively. The increase in contributions in 2018 and 2017 were due, in part, to an increase in participation in the international plans due to an increase in headcount at MTCH and ANGI as a result of continued business growth.

CONSOLIDATED FINANCIAL STATEMEN

CONSOLIDATED FINANCIAL STATEMENT DETAILS	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
CONSOLIDATED FINANCIAL STATEMENT DETAILS	CONSOLIDATED FINANCIAL STATEMENT DETAILS December 31, 2018 2017 (In thousands) Other current assets: Capitalized costs to obtain a contract with a customer $ 69,817 $ — Prepaid expenses 55,586 49,350 Capitalized downloadable search toolbar costs, net 33,365 31,588 Income taxes receivable 10,132 33,239 Production costs 2,260 18,570 Other 57,093 52,627 Other current assets $ 228,253 $ 185,374 December 31, 2018 2017 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 249,026 $ 246,038 Computer equipment and capitalized software 229,083 218,529 Furniture and other equipment 86,694 88,930 Projects in progress 29,204 19,094 Land 11,591 14,390 Property and equipment 605,598 586,981 Accumulated depreciation and amortization (286,798 ) (271,811 ) Property and equipment, net of accumulated depreciation and amortization $ 318,800 $ 315,170 December 31, 2018 2017 (In thousands) Accrued expenses and other current liabilities: Accrued employee compensation and benefits $ 137,583 $ 108,431 Accrued advertising expense 105,520 96,445 Other 191,783 162,048 Accrued expenses and other current liabilities $ 434,886 $ 366,924 Years Ended December 31, 2018 2017 2016 (In thousands) Revenue: Service revenue $ 4,249,227 $ 3,302,937 $ 2,967,474 Product revenue 13,665 4,302 172,408 Revenue $ 4,262,892 $ 3,307,239 $ 3,139,882 Years Ended December 31, 2018 2017 2016 (In thousands) Cost of revenue: Cost of service revenue $ 898,736 $ 647,226 $ 617,058 Cost of product revenue 12,410 3,782 138,672 Cost of revenue $ 911,146 $ 651,008 $ 755,730 Years Ended December 31, 2018 2017 2016 (In thousands) Other income (expense), net $ 305,746 $ (16,213 ) $ 60,650 Other income, net in 2018 includes: $124.2 million of net unrealized gains related to certain equity investments that were adjusted to fair value in accordance with ASU No. 2016-01, which was adopted on January 1, 2018; $120.6 million in gains related to the sales of Dictionary.com, Electus, Felix and CityGrid; $30.4 million of interest income; $27.9 million in realized gains related to the sale of certain equity investments; and $5.3 million in net foreign currency exchange gains due primarily to the strengthening of the dollar relative to the British Pound. Other expense, net in 2017 includes: $16.8 million in net foreign currency exchange losses due primarily to the weakening of the dollar relative to the British Pound; $15.4 million expense related to the extinguishment of the 6.75% MTCH Senior Notes and repricing of the MTCH Term Loan; $13.0 million mark-to-market charge principally pertaining to a subsidiary denominated equity award held by a non-employee; $12.2 million in other-than-temporary impairment charges related to certain investments; $1.2 million expense related to the write-off of deferred financing costs associated with the repayment of the 4.875% Senior Notes; $34.9 million in realized gains related to the sale of certain investments; and $11.4 million of interest income. Other income, net in 2016 includes: $37.5 million and $12.0 million in realized gains related to the sales of ShoeBuy and PriceRunner, respectively; $34.4 million in net foreign currency exchange gains due primarily to the strengthening of the dollar relative to the British Pound and Euro; $5.1 million of interest income; $3.6 million gain related to the sale of certain equity investments; $12.1 million non-cash charge related to the write-off of a proportionate share of original issue discount and deferred financing costs associated with the repayment of $440 million of the MTCH Term Loan; $10.7 million in other-than-temporary impairment charges related to certain investments; $3.8 million loss related to the sale of ASKfm; $3.6 million loss on the 4.75% and 4.875% Senior Note redemptions and repurchases; and $2.5 million mark-to-market charge principally pertaining to a subsidiary denominated equity award held by a non-employee.

TRANSACTION AND INTEGRATION REL

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION	BUSINESS COMBINATION Through the Combination, ANGI acquired 100% of the common stock of Angie's List on September 29, 2017 for a total purchase price valued at $781.4 million . The purchase price of $781.4 million was determined based on the sum of (i) the fair value of the 61.3 million shares of Angie's List common stock outstanding immediately prior to the Combination based on the closing stock price of Angie's List common stock on the NASDAQ on September 29, 2017 of $12.46 per share; (ii) the cash consideration of $1.9 million paid to holders of Angie's List common stock who elected to receive $8.50 in cash per share; and (iii) the fair value of vested equity awards (including the pro rata portion of unvested awards attributable to pre-combination services) outstanding under Angie's List stock plans on September 29, 2017 . Each stock option to purchase shares of Angie's List common stock that was outstanding immediately prior to the effective time of the Combination was, as of the effective time of the Combination, converted into an option to purchase (i) that number of Class A shares of ANGI Homeservices equal to the total number of shares of Angie's List common stock subject to such Angie's List option immediately prior to the effective time of the Combination, (ii) at a per-share exercise price equal to the exercise price per share of Angie's List common stock at which such Angie's List option was exercisable immediately prior to the effective time of the Combination. Each award of Angie's List restricted stock units that was outstanding immediately prior to the effective time of the Combination was, as of the effective time of the Combination, converted into an ANGI Homeservices restricted stock unit award with respect to a number of Class A shares of ANGI Homeservices equal to the total number of shares of Angie's List common stock subject to such Angie's List restricted stock unit award immediately prior to the effective time of the Combination. The table below summarizes the purchase price: Angie's List (In thousands) Class A common stock $ 763,684 Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock 1,913 Fair value of vested and pro rata portion of unvested stock options attributable to pre-combination services 11,749 Fair value of the pro rata portion of unvested restricted stock units attributable to pre-combination services 4,038 Total purchase price $ 781,384 The financial results of Angie's List are included in the Company's consolidated financial statements, within the ANGI Homeservices segment, beginning September 29, 2017 . For the year ended December 31, 2017 , the Company included $58.9 million of revenue and $21.8 million of net loss in its consolidated statement of operations related to Angie's List. The net loss of Angie's List reflects $28.7 million in stock-based compensation expense related to (i) the acceleration of previously issued Angie's List equity awards held by employees terminated in connection with the Combination and (ii) the expense related to previously issued Angie's List equity awards, severance and retention costs of $19.8 million related to the Combination and a reduction in revenue of $7.8 million due to the write-off of deferred revenue related to the Combination. The table below summarizes the fair values of the assets acquired and liabilities assumed at the date of combination: Angie's List (In thousands) Cash and cash equivalents $ 44,270 Other current assets 11,280 Property and equipment 16,341 Goodwill 543,674 Intangible assets 317,300 Total assets 932,865 Deferred revenue (32,595 ) Other current liabilities (46,150 ) Long-term debt—related party (61,498 ) Deferred income taxes (9,833 ) Other long-term liabilities (1,405 ) Net assets acquired $ 781,384 The purchase price was based on the expected financial performance of Angie's List, not on the value of the net identifiable assets at the time of combination. This resulted in a significant portion of the purchase price being attributed to goodwill because Angie's List is complementary and synergistic to the other North America businesses of ANGI Homeservices. The fair values of the identifiable intangible assets acquired at the date of combination are as follows: Angie's List (In thousands) Weighted-Average Useful Life (Years) Indefinite-lived trade name and trademarks $ 137,000 Indefinite Service professionals 90,500 3 Developed technology 63,900 6 Memberships 15,900 3 User base 10,000 1 Total identifiable intangible assets acquired $ 317,300 Other current assets, current liabilities and other long-term liabilities of Angie's List were reviewed and adjusted to their fair values at the date of combination, as necessary. The fair value of deferred revenue was determined using an income approach that utilized a cost to fulfill analysis. The fair value of the trade name and trademarks was determined using an income approach that utilized the relief from royalty methodology. The fair values of developed technology and user base were determined using a cost approach that utilized the cost to replace methodology. The fair values of the service professionals and memberships were determined using an income approach that utilized the excess earnings methodology. The valuations of deferred revenue and intangible assets incorporate significant unobservable inputs and require significant judgment and estimates, including the amount and timing of future cash flows, cost and profit margins related to deferred revenue and the determination of royalty and discount rates. The amount attributed to goodwill is not tax deductible. Unaudited Pro Forma Financial Information The unaudited pro forma financial information in the table below presents the combined results of the Company and Angie's List as if the Combination had occurred on January 1, 2016. The unaudited pro forma financial information includes adjustments required under the acquisition method of accounting and is presented for informational purposes only and is not necessarily indicative of the results that would have been achieved had the Combination actually occurred on January 1, 2016. For the year ended December 31, 2017 , pro forma adjustments include (i) reductions in stock-based compensation expense of $77.1 million and transaction related costs of $34.1 million because they are one-time in nature and will not have a continuing impact on operations; and (ii) an increase in amortization of intangibles of $31.9 million . The stock-based compensation expense is related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination. The transaction related costs include severance and retention costs of $19.8 million related to the Combination. For the year ended December 31, 2016, pro forma adjustments include a reduction in revenue of $34.1 million due to the write-off of deferred revenue at the assumed date of acquisition as well as increases in stock-based compensation expense of $81.4 million and amortization of intangibles of $56.1 million . Years Ended December 31, 2017 2016 (In thousands, except per share data) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to ANGI Homeservices Inc. shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.27 $ (1.79 ) TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION During the years ended December 31, 2018 and 2017, the Company incurred $3.6 million and $44.1 million , respectively, in costs related to the Combination (including severance, retention, transaction and integration related costs), as well as deferred revenue write-offs of $5.5 million and $7.8 million , respectively. During the years ended December 31, 2018 and 2017, the Company also incurred $70.6 million and $122.1 million , respectively, in stock-based compensation expense related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination. See " Note 4—Business Combination " for additional information on the Combination. A summary of the costs incurred, payments made and the related accrual is presented below. Years Ended December 31, 2018 2017 (In thousands) Transaction and integration related costs $ 3,584 $ 44,101 Stock-based compensation expense 70,645 122,066 Total $ 74,229 $ 166,167 December 31, 2018 2017 (In thousands) Accrual as of January 1 $ 8,480 $ — Costs incurred 3,584 44,101 Payments made (12,064 ) (35,621 ) Accrual as of December 31 $ — $ 8,480 The costs are allocated as follows in the accompanying consolidated statement of operations: Year Ended December 31, 2018 Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense — 2,161 2,161 General and administrative expense 3,584 61,010 64,594 Product development expense — 7,474 7,474 Total $ 3,584 $ 70,645 $ 74,229 Year Ended December 31, 2017 Transaction and Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense 7,430 24,416 31,846 General and administrative expense 36,120 83,420 119,540 Product development expense 551 14,230 14,781 Total $ 44,101 $ 122,066 $ 166,167

GUARANTOR AND NON-GUARANTOR FIN

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2018
Guarantor and Nonguarantor Financial Statements [Abstract]
GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION	GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION The 4.75% Senior Notes are unconditionally guaranteed, jointly and severally, by certain domestic subsidiaries which are 100% owned by the Company. The following tables present condensed consolidating financial information at December 31, 2018 and 2017 and for the years ended December 31, 2018 , 2017 and 2016 for: IAC, on a standalone basis; the combined guarantor subsidiaries of IAC; the combined non-guarantor subsidiaries of IAC; and IAC on a consolidated basis. Balance sheet at December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 1,018,082 $ — $ 1,113,550 $ — $ 2,131,632 Marketable securities 98,299 — 25,366 — 123,665 Accounts receivable, net of allowance and reserves — 99,970 179,219 — 279,189 Other current assets 27,349 29,222 171,682 — 228,253 Intercompany receivables — 1,423,456 — (1,423,456 ) — Property and equipment, net of accumulated depreciation and amortization 6,526 163,281 148,993 — 318,800 Goodwill — 412,009 2,314,850 — 2,726,859 Intangible assets, net of accumulated amortization — 43,914 587,508 — 631,422 Investment in subsidiaries 1,897,699 214,519 — (2,112,218 ) — Other non-current assets 274,789 94,290 251,315 (185,629 ) 434,765 Total assets $ 3,322,744 $ 2,480,661 $ 4,792,483 $ (3,721,303 ) $ 6,874,585 Current portion of long-term debt $ — $ — $ 13,750 $ — $ 13,750 Accounts payable, trade 1,304 36,293 37,310 — 74,907 Other current liabilities 41,721 95,405 657,775 — 794,901 Long-term debt, net 34,262 — 2,211,286 — 2,245,548 Income taxes payable 15 1,707 35,862 — 37,584 Intercompany liabilities 402,056 — 1,021,400 (1,423,456 ) — Other long-term liabilities 261 18,181 257,594 (185,629 ) 90,407 Redeemable noncontrolling interests — — 65,687 — 65,687 Shareholders' equity (deficit) 2,843,125 2,329,075 (216,857 ) (2,112,218 ) 2,843,125 Noncontrolling interests — — 708,676 — 708,676 Total liabilities and shareholders' equity $ 3,322,744 $ 2,480,661 $ 4,792,483 $ (3,721,303 ) $ 6,874,585 Balance sheet at December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 585,639 $ — $ 1,045,170 $ — $ 1,630,809 Marketable securities 4,995 — — — 4,995 Accounts receivable, net of allowance and reserves 31 109,289 194,707 — 304,027 Other current assets 49,159 33,387 102,828 — 185,374 Intercompany receivables — 668,703 — (668,703 ) — Property and equipment, net of accumulated depreciation and amortization 2,811 174,323 138,036 — 315,170 Goodwill — 412,010 2,147,056 — 2,559,066 Intangible assets, net of accumulated amortization — 74,852 588,885 — 663,737 Investment in subsidiaries 2,077,898 554,998 — (2,632,896 ) — Other non-current assets 170,073 87,306 79,688 (132,435 ) 204,632 Total assets $ 2,890,606 $ 2,114,868 $ 4,296,370 $ (3,434,034 ) $ 5,867,810 Current portion of long-term debt $ — $ — $ 13,750 $ — $ 13,750 Accounts payable, trade 5,163 30,469 40,939 — 76,571 Other current liabilities 29,489 88,050 591,868 — 709,407 Long-term debt, net 34,572 — 1,944,897 — 1,979,469 Income taxes payable 16 1,605 24,003 — 25,624 Intercompany liabilities 390,827 — 277,876 (668,703 ) — Other long-term liabilities 511 18,613 186,610 (132,435 ) 73,299 Redeemable noncontrolling interests — — 42,867 — 42,867 Shareholders' equity 2,430,028 1,976,131 656,765 (2,632,896 ) 2,430,028 Noncontrolling interests — — 516,795 — 516,795 Total liabilities and shareholders' equity $ 2,890,606 $ 2,114,868 $ 4,296,370 $ (3,434,034 ) $ 5,867,810 Statement of operations for the year ended December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 850,475 $ 3,412,795 $ (378 ) $ 4,262,892 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 195 262,912 648,330 (291 ) 911,146 Selling and marketing expense 977 313,769 1,204,844 (150 ) 1,519,440 General and administrative expense 141,727 49,563 582,720 69 774,079 Product development expense 2,003 56,431 250,901 (6 ) 309,329 Depreciation 1,203 12,497 61,660 — 75,360 Amortization of intangibles — 29,437 78,962 — 108,399 Total operating costs and expenses 146,105 724,609 2,827,417 (378 ) 3,697,753 Operating (loss) income (146,105 ) 125,866 585,378 — 565,139 Equity in earnings of unconsolidated affiliates 731,834 20,083 — (751,917 ) — Interest expense (1,700 ) — (107,627 ) — (109,327 ) Other (expense) income, net (a) (18,834 ) 503,261 199,757 (378,438 ) 305,746 Earnings before income taxes 565,195 649,210 677,508 (1,130,355 ) 761,558 Income tax benefit (provision) 61,766 (56,612 ) (8,965 ) — (3,811 ) Net earnings 626,961 592,598 668,543 (1,130,355 ) 757,747 Net earnings attributable to noncontrolling interests — — (130,786 ) — (130,786 ) Net earnings attributable to IAC shareholders $ 626,961 $ 592,598 $ 537,757 $ (1,130,355 ) $ 626,961 Comprehensive income attributable to IAC shareholders $ 601,683 $ 601,232 $ 515,766 $ (1,116,998 ) $ 601,683 ____________________ (a) During the year ended December 31, 2018, foreign cash of $396.2 million was repatriated to the U.S, of which $25.2 million was between non-guarantor subsidiaries. Statement of operations for the year ended December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 753,858 $ 2,553,998 $ (617 ) $ 3,307,239 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 160 159,488 491,865 (505 ) 651,008 Selling and marketing expense 1,250 353,186 1,027,304 (519 ) 1,381,221 General and administrative expense 100,237 62,340 556,273 407 719,257 Product development expense 2,421 55,232 193,226 — 250,879 Depreciation 1,564 20,668 52,033 — 74,265 Amortization of intangibles — 11,213 30,930 — 42,143 Total operating costs and expenses 105,632 662,127 2,351,631 (617 ) 3,118,773 Operating (loss) income (105,632 ) 91,731 202,367 — 188,466 Equity in earnings of unconsolidated affiliates 419,149 20,755 — (439,904 ) — Interest expense (20,339 ) — (84,956 ) — (105,295 ) Other (expense) income, net (30,787 ) 28,434 (13,860 ) — (16,213 ) Earnings before income taxes 262,391 140,920 103,551 (439,904 ) 66,958 Income tax benefit (provision) 42,533 (119,957 ) 368,474 — 291,050 Net earnings 304,924 20,963 472,025 (439,904 ) 358,008 Net earnings attributable to noncontrolling interests — — (53,084 ) — (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 $ 20,963 $ 418,941 $ (439,904 ) $ 304,924 Comprehensive income attributable to IAC shareholders $ 367,370 $ 7,629 $ 498,032 $ (505,661 ) $ 367,370 Statement of operations for the year ended December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 960,000 $ 2,180,487 $ (605 ) $ 3,139,882 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 859 297,712 457,571 (412 ) 755,730 Selling and marketing expense 2,353 417,051 828,016 (323 ) 1,247,097 General and administrative expense 89,583 83,636 357,097 130 530,446 Product development expense 4,807 69,778 138,180 — 212,765 Depreciation 1,610 26,514 43,552 — 71,676 Amortization of intangibles — 41,157 38,269 — 79,426 Goodwill impairment — 253,245 22,122 — 275,367 Total operating costs and expenses 99,212 1,189,093 1,884,807 (605 ) 3,172,507 Operating (loss) income (99,212 ) (229,093 ) 295,680 — (32,625 ) Equity in earnings of unconsolidated affiliates 49,545 6,774 — (56,319 ) — Interest expense (26,876 ) — (82,234 ) — (109,110 ) Other (expense) income, net (1,879 ) 10,209 52,320 — 60,650 (Loss) earnings before income taxes (78,422 ) (212,110 ) 265,766 (56,319 ) (81,085 ) Income tax benefit (provision) 37,142 77,851 (50,059 ) — 64,934 Net (loss) earnings (41,280 ) (134,259 ) 215,707 (56,319 ) (16,151 ) Net earnings attributable to noncontrolling interests — — (25,129 ) — (25,129 ) Net (loss) earnings attributable to IAC shareholders $ (41,280 ) $ (134,259 ) $ 190,578 $ (56,319 ) $ (41,280 ) Comprehensive (loss) income attributable to IAC shareholders $ (76,431 ) $ (142,494 ) $ 145,039 $ (2,545 ) $ (76,431 ) Statement of cash flows for the year ended December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (38,737 ) $ 583,498 $ 822,227 $ (378,860 ) $ 988,128 Cash flows from investing activities: Acquisitions, net of cash acquired (4,142 ) (50,530 ) (9,824 ) — (64,496 ) Capital expenditures (5,274 ) (1,396 ) (78,964 ) — (85,634 ) Proceeds from maturities and sales of marketable debt securities 298,600 — 35,000 — 333,600 Purchases of marketable debt securities (390,005 ) — (59,671 ) — (449,676 ) Net proceeds from the sale of businesses and investments 408 87,254 49,057 — 136,719 Purchases of investments (39,180 ) — (13,800 ) — (52,980 ) Other, net (5,000 ) 7,451 6,576 — 9,027 Net cash (used in) provided by investing activities (144,593 ) 42,779 (71,626 ) — (173,440 ) Cash flows from financing activities: Repurchases of IAC debt (363 ) — — — (363 ) Proceeds from issuance of Match Group debt — — 260,000 — 260,000 Principal payments on ANGI Homeservices Term Loan — — (13,750 ) — (13,750 ) Debt issuance costs — — (5,449 ) — (5,449 ) Purchase of IAC treasury stock (82,891 ) — — — (82,891 ) Purchase of Match Group treasury stock — — (133,455 ) — (133,455 ) Proceeds from the exercise of IAC stock options 41,700 — — — 41,700 Proceeds from the exercise of Match Group and ANGI Homeservices stock options — — 4,705 — 4,705 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (18,982 ) — — — (18,982 ) Withholding taxes paid on behalf of Match Group and ANGI Homeservices employees on net settled stock-based awards — — (237,564 ) — (237,564 ) Dividends paid to Match Group noncontrolling interests — — (105,126 ) — (105,126 ) Purchase of noncontrolling interests — — (16,063 ) — (16,063 ) Acquisition-related contingent consideration payments — — (185 ) — (185 ) Intercompany 673,308 (625,338 ) (426,830 ) 378,860 — Other, net 2,674 (939 ) (7,110 ) — (5,375 ) Net cash provided by (used in) financing activities 615,446 (626,277 ) (680,827 ) 378,860 (312,798 ) Total cash provided 432,116 — 69,774 — 501,890 Effect of exchange rate changes on cash, cash equivalents, and restricted cash 327 — (2,214 ) — (1,887 ) Net increase in cash, cash equivalents, and restricted cash 432,443 — 67,560 — 500,003 Cash, cash equivalents, and restricted cash at beginning of period 585,639 — 1,048,043 — 1,633,682 Cash, cash equivalents, and restricted cash at end of period $ 1,018,082 $ — $ 1,115,603 $ — $ 2,133,685 Statement of cash flows for the year ended December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (52,582 ) $ 131,700 $ 337,581 $ 416,699 Cash flows from investing activities: Acquisitions, net of cash acquired — (2,550 ) (144,003 ) (146,553 ) Capital expenditures (337 ) (1,169 ) (74,017 ) (75,523 ) Proceeds from maturities and sales of marketable debt securities 114,350 — — 114,350 Purchases of marketable debt securities (29,891 ) — — (29,891 ) Net proceeds from the sale of businesses and investments 1,266 — 184,512 185,778 Purchases of investments — — (9,106 ) (9,106 ) Other, net — 1,944 1,050 2,994 Net cash provided by (used in) investing activities 85,388 (1,775 ) (41,564 ) 42,049 Cash flows from financing activities: Proceeds from issuance of IAC debt — — 517,500 517,500 Repurchases of IAC debt (393,464 ) — — (393,464 ) Proceeds from issuance of Match Group debt — — 525,000 525,000 Principal payments on Match Group debt — — (445,172 ) (445,172 ) Borrowing under ANGI Homeservices Term Loan — — 275,000 275,000 Purchase of exchangeable note hedge — — (74,365 ) (74,365 ) Proceeds from issuance of warrants 23,650 — — 23,650 Debt issuance costs — — (33,744 ) (33,744 ) Purchase of IAC treasury stock (56,424 ) — — (56,424 ) Proceeds from the exercise of IAC stock options 82,397 — — 82,397 Proceeds from the exercise of Match Group and ANGI Homeservices stock options — — 61,095 61,095 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (93,832 ) — — (93,832 ) Withholding taxes paid on behalf of Match Group and ANGI Homeservices employees on net settled stock-based awards — — (264,323 ) (264,323 ) Purchase of Match Group stock-based awards — — (272,459 ) (272,459 ) Purchase of noncontrolling interests — — (15,439 ) (15,439 ) Acquisition-related contingent consideration payments — — (27,289 ) (27,289 ) Intercompany 416,396 (129,925 ) (286,471 ) — Other, net 251 — (5,251 ) (5,000 ) Net cash used in financing activities (21,026 ) (129,925 ) (45,918 ) (196,869 ) Total cash provided 11,780 — 250,099 261,879 Effect of exchange rate changes on cash, cash equivalents, and restricted cash 75 — 11,529 11,604 Net increase in cash, cash equivalents, and restricted cash 11,855 — 261,628 273,483 Cash, cash equivalents, and restricted cash at beginning of period 573,784 — 786,415 1,360,199 Cash, cash equivalents, and restricted cash at end of period $ 585,639 $ — $ 1,048,043 $ 1,633,682 Statement of cash flows for the year ended December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (62,686 ) $ 128,503 $ 278,421 $ — $ 344,238 Cash flows from investing activities: Acquisitions, net of cash acquired — — (18,403 ) — (18,403 ) Capital expenditures (479 ) (5,792 ) (71,768 ) — (78,039 ) Proceeds from maturities and sales of marketable debt securities 252,369 — — — 252,369 Purchases of marketable debt securities (313,943 ) — — — (313,943 ) Investments in time deposits — — (87,500 ) — (87,500 ) Proceeds from maturities of time deposits — — 87,500 — 87,500 Net proceeds from the sale of businesses and investments 73,843 1,779 96,606 — 172,228 Purchases of investments — — (12,565 ) — (12,565 ) Intercompany (155,104 ) — — 155,104 — Other, net 126 910 10,179 — 11,215 Net cash (used in) provided by investing activities (143,188 ) (3,103 ) 4,049 155,104 12,862 Cash flows from financing activities: Repurchases of IAC debt (126,409 ) — — — (126,409 ) Proceeds from issuance of Match Group debt — — 400,000 — 400,000 Principal payments on Match Group debt — — (450,000 ) — (450,000 ) Debt issuance costs — — (7,811 ) — (7,811 ) Purchase of IAC treasury stock (308,948 ) — — — (308,948 ) Proceeds from the exercise of IAC stock options 25,821 — — — 25,821 Proceeds from the exercise of Match Group stock options — — 39,378 — 39,378 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (26,716 ) — — — (26,716 ) Withholding taxes paid on behalf of Match Group employees on net settled stock-based awards — — (29,830 ) — (29,830 ) Purchase of noncontrolling interests (1,400 ) — (1,340 ) — (2,740 ) Acquisition-related contingent consideration payments — (351 ) (1,829 ) — (2,180 ) Intercompany 122,965 (122,965 ) 155,104 (155,104 ) — Other, net (313 ) (2,084 ) (308 ) — (2,705 ) Net cash (used in) provided by financing activities (315,000 ) (125,400 ) 103,364 (155,104 ) (492,140 ) Total cash (used) provided (520,874 ) — 385,834 — (135,040 ) Effect of exchange rate changes on cash, cash equivalents, and restricted cash — — (6,434 ) — (6,434 ) Net (decrease) increase in cash, cash equivalents, and restricted cash (520,874 ) — 379,400 — (141,474 ) Cash, cash equivalents, and restricted cash at beginning of period 1,094,658 — 407,015 — 1,501,673 Cash, cash equivalents, and restricted cash at end of period $ 573,784 $ — $ 786,415 $ — $ 1,360,199

QUARTERLY RESULTS (UNAUDITED)

QUARTERLY RESULTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS (UNAUDITED)	QUARTERLY RESULTS (UNAUDITED) Quarter Ended March 31 (a) Quarter Ended June 30 (b) Quarter Ended September 30 (c) Quarter Ended December 31 (d) (In thousands, except per share data) Year Ended December 31, 2018 Revenue $ 995,075 $ 1,059,122 $ 1,104,592 $ 1,104,103 Cost of revenue 201,962 218,224 237,238 253,722 Operating income 89,950 168,437 172,832 133,920 Net earnings 87,839 280,854 171,577 217,477 Net earnings attributable to IAC shareholders 71,082 218,353 145,774 191,752 Per share information attributable to IAC shareholders: Basic earnings per share (g) $ 0.86 $ 2.61 $ 1.75 $ 2.29 Diluted earnings per share (g) $ 0.71 $ 2.32 $ 1.49 $ 2.04 Quarter Ended March 31 Quarter Ended June 30 Quarter Ended September 30 (e) Quarter Ended December 31 (f) (In thousands, except per share data) Year Ended December 31, 2017 Revenue $ 760,833 $ 767,387 $ 828,434 $ 950,585 Cost of revenue 145,958 139,033 166,290 199,727 Operating income (loss) 37,060 75,635 (18,589 ) 94,360 Net earnings 28,463 80,557 225,639 23,349 Net earnings attributable to IAC shareholders 26,209 66,268 179,643 32,804 Per share information attributable to IAC shareholders: Basic earnings per share (g) $ 0.34 $ 0.84 $ 2.22 $ 0.40 Diluted earnings per share (g) $ 0.29 $ 0.70 $ 1.79 $ 0.37 _______________________________________________________________________________ (a) The first quarter of 2018 includes after-tax stock-based compensation expense of $14.6 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination, as well as after-tax costs of $4.1 million related to the Combination (including $2.8 million of deferred revenue write-offs). (b) The second quarter of 2018 includes: i. after-tax stock-based compensation expense of $12.8 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination, as well as after-tax costs of $2.0 million related to the Combination (including $1.8 million of deferred revenue write-offs). ii. after-tax realized and unrealized gains of $133.3 million related to the sale of a certain equity investment. (c) The third quarter of 2018 includes after-tax stock-based compensation expense of $12.3 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination. (d) The fourth quarter of 2018 includes: i. after-tax stock-based compensation expense of $14.4 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination. ii. combined after-tax gains of $92.5 million related to the sales of Dictionary.com, Electus, Felix and CityGrid. iii. after-tax impairment charges related to indefinite-lived intangible assets of $21.3 million . (e) The third quarter of 2017 includes: i. after-tax stock-based compensation expense of $60.9 million related to the modification of previously issued HomeAdvisor vested awards, which were converted into ANGI Homeservices equity awards, and the acceleration of certain Angie’s List equity awards in connection with the Combination, as well as after-tax costs of $17.4 million related to the Combination. ii. a reduction to the income tax provision of $257.0 million related to excess tax benefits generated by the exercise, purchase and settlement of stock-based awards. (f) The fourth quarter of 2017 includes after-tax stock-based compensation expense of $15.8 million related to the modification of previously issued HomeAdvisor unvested awards, which were converted into ANGI Homeservices equity awards, the expense related to previously issued Angie's List equity awards and the acceleration of certain Angie's List equity awards resulting from the termination of employees in connection with the Combination, as well as after-tax costs of $13.9 million related to the Combination (including $7.6 million of deferred revenue write-offs). (g) Quarterly per share amounts may not add to the related annual per share amount because of differences in the average common shares outstanding during each period.

SUBSEQUENT EVENTS (UNAUDITED)

SUBSEQUENT EVENTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENTS (UNAUDITED)	SUBSEQUENT EVENTS (UNAUDITED) On February 11, 2019, the Company and Google amended the services agreement, effective as of April 1, 2020. The amendment extends the expiration date of the agreement to March 31, 2023; provided that beginning September 2020 and each September thereafter, either party may, after discussion with the other party, terminate the services agreement, effective on September 30 of the year following the year such notice is given. The Company believes that the amended agreement, taken as a whole, is comparable to the Company’s previously existing agreement with Google. On February 15, 2019, MTCH completed a private offering of $350 million aggregate principal amount of its 5.625% Senior Notes due 2029. A portion of the proceeds from these notes were used to repay outstanding borrowings under the MTCH Credit Facility and to pay expenses associated with the offering; the remaining proceeds will be used for general corporate purposes.

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	Schedule II IAC/INTERACTIVECORP AND SUBSIDIARIES VALUATION AND QUALIFYING ACCOUNTS Description Balance at Beginning of Period Charges to Earnings Charges to Other Accounts Deductions Balance at End of Period (In thousands) 2018 Allowance for doubtful accounts and revenue reserves $ 11,489 $ 48,445 (a) $ (573 ) $ (40,501 ) (d) $ 18,860 Deferred tax valuation allowance 132,598 (20,746 ) (b) 4,001 (c) — 115,853 Other reserves 2,544 7,734 2017 Allowance for doubtful accounts and revenue reserves $ 16,405 $ 28,930 (a) $ (1,006 ) $ (32,840 ) (d) $ 11,489 Sales returns accrual 80 — (80 ) — — Deferred tax valuation allowance 88,170 38,144 (e) 6,284 (f) — 132,598 Other reserves 2,822 2,544 2016 Allowance for doubtful accounts and revenue reserves $ 16,528 $ 17,733 (a) $ (695 ) $ (17,161 ) (d) $ 16,405 Sales returns accrual 828 14,998 (962 ) (14,784 ) 80 Deferred tax valuation allowance 90,482 (837 ) (g) (1,475 ) (h) — 88,170 Other reserves 2,801 2,822 _________________________________________________________ (a) Additions to the allowance for doubtful accounts are charged to expense. Additions to the revenue reserves are charged against revenue. (b) Amount is primarily related to a decrease in foreign tax credits subject to a valuation allowance and the realization of previously unbenefited capital losses, partially offset by an increase in state net operating losses and foreign interest deduction carryforwards. (c) Amount is primarily related to acquired federal and state NOLs, partially offset by currency translation adjustments on foreign NOLs. (d) Write-off of fully reserved accounts receivable. (e) Amount is due primarily to the establishment of foreign NOLs related to an acquisition. (f) Amount is primarily related to acquired state NOLs, acquired foreign tax credits and currency translation adjustments on foreign NOLs. (g) Amount is primarily related to other-than-temporary impairment charges for certain cost method investments and an increase in federal capital and NOLs, partially offset by a decrease in state NOLs, foreign tax credits, and foreign NOLs. (h) Amount is primarily related to the realization of previously unbenefited unrealized losses on available-for-sale marketable equity securities included in accumulated other comprehensive income and currency translation adjustments on foreign NOLs.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	The Company prepares its consolidated financial statements in accordance with U.S. generally accepted accounting principles ("GAAP").
Basis of Consolidation and Accounting for Investments and Equity Securities	The consolidated financial statements include the accounts of the Company, all entities that are wholly-owned by the Company and all entities in which the Company has a controlling financial interest. Intercompany transactions and accounts have been eliminated. Accounting for Investments and Equity Securities Investments in the common stock or in-substance common stock of entities in which the Company has the ability to exercise significant influence over the operating and financial matters of the investee, but does not have a controlling financial interest, are accounted for using the equity method and are included in "Long-term investments" in the accompanying consolidated balance sheet. At December 31, 2018, the Company did not have any investments accounted for using the equity method. Investments in equity securities, other than those of our consolidated subsidiaries and those accounted for under the equity method, are accounted for at fair value or under the measurement alternative of Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , following its adoption on January 1, 2018, with any changes to fair value recognized within other income (expense), net each reporting period. Under the measurement alternative, equity investments without readily determinable fair values are carried at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer; value is generally determined based on a market approach as of the transaction date. An investment will be considered identical or similar if it has identical or similar rights to the equity investments held by the Company. The Company reviews its equity securities for impairment each reporting period when there are qualitative factors or events that indicate possible impairment. Factors we consider in making this determination include negative changes in industry and market conditions, financial performance, business prospects, and other relevant events and factors. When indicators of impairment exist, the Company prepares quantitative assessments of the fair value of our equity securities, which require judgment and the use of estimates. When our assessment indicates that the fair value of the security is below the carrying value, the Company writes down the security to its fair value and records the corresponding charge within other income (expense), net. See " Accounting Pronouncements adopted by the Company" below for further information.
Accounting Estimates	Accounting Estimates Management of the Company is required to make certain estimates, judgments and assumptions during the preparation of its consolidated financial statements in accordance with GAAP. These estimates, judgments and assumptions impact the reported amounts of assets, liabilities, revenue and expenses and the related disclosure of contingent assets and liabilities. Actual results could differ from these estimates. On an ongoing basis, the Company evaluates its estimates and judgments, including those related to: the recoverability of goodwill and indefinite-lived intangible assets; the useful lives and recoverability of definite-lived intangible assets and property and equipment; the fair values of marketable debt securities and equity securities without readily determinable fair values; the carrying value of accounts receivable, including the determination of the allowance for doubtful accounts; the determination of revenue reserves; the fair value of acquisition-related contingent consideration arrangements; unrecognized tax benefits; the valuation allowance for deferred income tax assets; and the fair value of and forfeiture rates for stock-based awards, among others. The Company bases its estimates and judgments on historical experience, its forecasts and budgets and other factors that the Company considers relevant.
Revenue Recognition	Revenue Recognition The Company adopted the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, effective January 1, 2018 using the modified retrospective transition method for open contracts as of the date of initial application. See " Accounting Pronouncements adopted by the Company" below for further information. The Company accounts for a contract with a customer when it has approval and commitment from all parties, the rights of the parties and payment terms are identified, the contract has commercial substance and collectability of consideration is probable. Revenue is recognized when control of the promised services or goods is transferred to our customers, and in an amount that reflects the consideration the Company is contractually due in exchange for those services or goods. Transaction Price The objective of determining the transaction price is to estimate the amount of consideration the Company is due in exchange for its services or goods, including amounts that are variable. The Company determines the total transaction price, including an estimate of any variable consideration, at contract inception and reassesses this estimate each reporting period. The Company excludes from the measurement of transaction price all taxes assessed by governmental authorities that are both (i) imposed on and concurrent with a specific revenue-producing transaction and (ii) collected from customers. Accordingly, such tax amounts are not included as a component of revenue or cost of revenue. For contracts that have an original duration of one year or less, the Company uses the practical expedient available under ASU No. 2014-09 applicable to such contracts and does not consider the time value of money. Arrangements with Multiple Performance Obligations The Company’s contracts with customers may include multiple performance obligations. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The Company generally determines standalone selling prices based on the prices charged to customers, which are directly observable or based on an estimate if not directly observable. For our multiple performance obligation arrangements that include functional intellectual property ("IP"), which comprise the downloadable apps and software of the Applications segment, the Company uses a residual approach to determine standalone selling prices for the functional IP. Assets Recognized from the Costs to Obtain a Contract with a Customer The Company has determined that certain costs, primarily commissions paid to employees pursuant to certain sales incentive programs and mobile app store fees, meet the requirements to be capitalized as a cost of obtaining a contract. Commissions paid to employees pursuant to certain sales incentive programs are amortized over the estimated customer relationship period. The Company calculates the estimated customer relationship period as the average customer life, which is based on historical data. When customer renewals are expected and the renewal commission is not commensurate with the initial commission, the average customer life includes renewal periods. For sales incentive programs where the customer relationship period is one year or less, the Company has elected the practical expedient to expense the costs as incurred. The Company generally capitalizes and amortizes mobile app store fees over the term of the applicable subscription. During the year ended December 31, 2018, the Company recognized expense of $355.3 million related to the amortization of these costs. The current and non-current contract asset balances at December 31, 2018 are $69.8 million and $4.5 million , respectively. The current and non-current contract assets are included in "Other current assets" and "Other non-current assets," respectively, in the accompanying consolidated balance sheet. Performance Obligations As permitted under the practical expedient available under ASU No. 2014-09, the Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less, (ii) contracts with variable consideration that is allocated entirely to unsatisfied performance obligations or to a wholly unsatisfied promise accounted for under the series guidance, and (iii) contracts for which the Company recognizes revenue at the amount which we have the right to invoice for services performed. Match Group Match Group revenue is primarily derived directly from users in the form of recurring subscriptions. Subscription revenue is presented net of credits and credit card chargebacks. Subscribers pay in advance, primarily by credit card or through mobile app stores, and, subject to certain conditions identified in our terms and conditions, generally all purchases are final and nonrefundable. Revenue is initially deferred and is recognized using the straight-line method over the term of the applicable subscription period, which generally ranges from one to six months . Revenue is also earned from online advertising, the purchase of à la carte features and offline events. Online advertising revenue is recognized when an advertisement is displayed. Revenue from the purchase of à la carte features is recognized based on usage. Revenue associated with offline events is recognized when each event occurs. ANGI Homeservices ANGI revenue is primarily derived from (i) consumer connection revenue, which comprises fees paid by HomeAdvisor service professionals for consumer matches (regardless of whether the service professional ultimately provides the requested service) and booking fees from completed jobs sourced through the Handy platform, and (ii) membership subscription fees paid by HomeAdvisor service professionals. Consumer connection revenue varies based upon several factors, including the service requested, product experience offered and geographic location of service. The Company’s consumer connection revenue is generated and recognized when an in-network service professional is delivered a consumer match or when a job sourced through the Handy platform is completed. Membership subscription revenue from service professionals is initially deferred and is recognized using the straight-line method over the applicable subscription period, which is typically one year . Consumer connection revenue is generally billed one week following a consumer match, with payment due upon receipt of invoice or collected when a consumer schedules a job through the Handy platform. The Company maintains revenue reserves for potential credits for services provided by Handy service professionals to consumers. ANGI revenue is also derived from Angie's List (i) sales of time-based website, mobile and call center advertising to service professionals and (ii) membership subscription fees from consumers. Angie's List service professionals generally pay for advertisements in advance on a monthly or annual basis at the option of the service professional, with the average advertising contract term being approximately one year. Angie's List website, mobile and call center advertising revenue is recognized ratably over the contract term. Revenue from the sale of advertising in the Angie’s List Magazine is recognized in the period in which the publication is distributed. Angie's List prepaid consumer membership subscription fees are recognized as revenue using the straight-line method over the term of the applicable subscription period, which is typically one year . Vimeo Vimeo revenue is derived primarily from annual and monthly SaaS subscription fees paid by creators for premium capabilities and, to a lesser extent, sales of live streaming hardware, software and professional services. Subscription revenue is recognized over the terms of the applicable subscription period, which are typically one month or one year . Dotdash Dotdash revenue consists principally of digital advertising revenue and affiliate commerce commission revenue. Digital advertising revenue is generated primarily through digital display advertisements sold directly and through programmatic advertising networks. Affiliate commerce commission revenue is generated when Dotdash refers users to commerce partner websites resulting in a purchase or transaction. Applications Desktop revenue largely consists of advertising revenue generated principally through the display of paid listings in response to search queries. The substantial majority of the paid listings displayed by our Desktop businesses is supplied to us by Google Inc. ("Google") pursuant to our services agreement with Google. Pursuant to this agreement, those of our Desktop businesses that provide search services transmit search queries to Google, which in turn transmits a set of relevant and responsive paid listings back to these businesses for display in search results. This ad-serving process occurs independently of, but concurrently with, the generation of algorithmic search results for the same search queries. Google paid listings are displayed separately from algorithmic search results and are identified as sponsored listings on search results pages. Paid listings are priced on a price per click basis and when a user submits a search query through one of our Desktop businesses and then clicks on a Google paid listing displayed in response to the query, Google bills the advertiser that purchased the paid listing directly and shares a portion of the fee charged to the advertiser with us. The Company recognizes paid listing revenue from Google when it delivers the user's click. In cases where the user’s click is generated due to the efforts of a third-party distributor, we recognize the amount due from Google as revenue and record a revenue share or other payment obligation to the third-party distributor as traffic acquisition costs. To a lesser extent, Desktop revenue also includes fees related to subscription downloadable desktop applications as well as display advertisements. Fees related to subscription downloadable desktop applications are generally recognized over the term of the applicable subscription period, which is primarily one or two years . Fees related to display advertisements are recognized when an advertisement is displayed. Mosaic Group revenue consists primarily of fees related to subscription downloadable mobile applications distributed through the Apple App and Google Play stores, as well as display advertisements. Fees related to subscription downloadable mobile applications are generally recognized at the time of the sale when the software license is delivered. To the extent updates or maintenance is required or expected, revenue is recognized over the term of the applicable subscription period, which is primarily one or two years . Fees related to display advertisements are recognized when an advertisement is displayed. Emerging & Other Revenue of Ask Media Group consists principally of advertising revenue, which is generated primarily through the display of paid listings in response to search queries and display advertisements (sold directly and through programmatic ad sales). The majority of the paid listings displayed are supplied to us by Google in the manner, and pursuant to the services agreement with Google, described above under "Applications." The Daily Beast revenue consists of advertising revenue, which is generated primarily through display advertisements (sold directly and through programmatic ad sales). BlueCrew revenue consists of service revenue, which is generated through staffing temporary workers and recognized as control of the promised services is transferred to our customers. Revenue of College Humor Media and IAC Films is generated primarily through media production and distribution and advertising. Production revenue is recognized when control is transferred to the customer to broadcast or exhibit, and advertising revenue is recognized when an advertisement is displayed or over the advertising period. Accounts Receivables, Net of Allowance for Doubtful Accounts and Revenue Reserves Accounts receivable include amounts billed and currently due from customers. The Company maintains an allowance for doubtful accounts to provide for the estimated amount of accounts receivable that will not be collected. The allowance for doubtful accounts is based upon a number of factors, including the length of time accounts receivable are past due, the Company’s previous loss history and the specific customer’s ability to pay its obligation. The time between the Company issuance of an invoice and payment due date is not significant; customer payments that are not collected in advance of the transfer of promised services or goods are generally due no later than 30 days from invoice date. The Company also maintains allowances to reserve for potential credits issued to consumers or other revenue adjustments. The amounts of these reserves are based primarily upon historical experience. Deferred Revenue Deferred revenue consists of advance payments that are received or are contractually due in advance of the Company's performance. The Company’s deferred revenue is reported on a contract by contract basis at the end of each reporting period. The Company classifies deferred revenue as current when the term of the applicable subscription period or expected completion of our performance obligation is one year or less. The deferred revenue balance at January 1, 2018 is $332.2 million . During the year ended December 31, 2018, the Company recognized $330.2 million of revenue that was included in the deferred revenue balance as of January 1, 2018. The current and non-current deferred revenue balances at December 31, 2018 are $360.0 million and $1.7 million , respectively. Non-current deferred revenue is included in "Other long-term liabilities" in the accompanying consolidated balance sheet.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include cash and short-term investments, with maturities of less than 91 days from the date of purchase. Domestically, cash equivalents primarily consist of AAA rated government money market funds, treasury discount notes, commercial paper rated A1/P1 or better, time deposits and certificates of deposit. Internationally, cash equivalents primarily consist of AAA rated government money market funds and time deposits.
Investments in Debt Securities	Investments in Debt Securities The Company invests in marketable debt securities with active secondary or resale markets to ensure portfolio liquidity to fund current operations or satisfy other cash requirements as needed. Marketable debt securities are adjusted to fair value each quarter, and the unrealized gains and losses, net of tax, are included in accumulated other comprehensive income (loss) as a separate component of shareholders' equity. The specific-identification method is used to determine the cost of debt securities sold and the amount of unrealized gains and losses reclassified out of accumulated other comprehensive income (loss) into earnings. The Company also invests in non-marketable debt securities as part of its investment strategy. We review our debt securities for impairment each reporting period. The Company recognizes an unrealized loss on debt securities in net earnings when the impairment is determined to be other-than-temporary. Factors we consider in making such determination include the duration, severity and reason for the decline in value and the potential recovery and our intent to sell the debt security. We also consider whether we will be required to sell the security before recovery of its amortized cost basis and whether the amortized cost basis cannot be recovered because of credit losses. If an impairment is considered to be other-than-temporary, the debt security will be written down to its fair value and the loss will be recognized within other income (expense), net. At December 31, 2018, marketable debt securities consist of treasury discount notes and commercial paper rated A1/P1 or better.
Certain Risks and Concentrations	Certain Risks and Concentrations A meaningful portion of the Company's revenue is derived from online advertising, the market for which is highly competitive and rapidly changing. Significant changes in this industry or changes in advertising spending behavior or in customer buying behavior could adversely affect our operating results. Most of the Company's online advertising revenue is attributable to a services agreement with Google Inc. ("Google"). For the years ended December 31, 2018 , 2017 and 2016 , consolidated revenue earned from Google w as $825.2 million , $740.7 million and $824.4 million , representing 19% , 22% and 26% , respectively, of the Company's consolidated revenue. A meaningful portion of this revenue is attributable to the service agreement with Google and earned by the Desktop business within the Applications segment and the Ask Media Group within the Emerging & Other segment. For the y ears end ed December 31, 2018 , 2017 and 2016 , revenue earned from Google represents 73% , 83% and 87% of Applications revenue and 94% , 96% and 96% of Ask Media Group revenue (and 68% , 48% and 35% of Emerging & Other revenue), respectively. Accounts receivable related to revenue earned from Google totaled $69.1 million and $72.4 million at December 31, 2018 and 2017 , respectively. The services agreement became effective on April 1, 2016, following the expiration of the previous services agreement, and expires on March 31, 2020. The services agreement requires that the Company comply with certain guidelines promulgated by Google. Google may generally unilaterally update its policies and guidelines without advance notice, which could in turn require modifications to, or prohibit and/or render obsolete certain of our products, services and/or business practices, which could be costly to address or otherwise have an adverse effect on our business, financial condition and results of operations. Google’s policy changes related to its Chrome browser became effective on September 12, 2018 and negatively impacted the distribution of our business-to-consumer ("B2C") desktop products. The impact of these changes on revenue and profits in 2018 were modest as the Company optimized marketing spend in anticipation of the changes. However, we expect these changes to reduce revenue and profits of the Desktop business in the future, which among other reasons led to a $27.7 million impairment of the related indefinite-lived intangible asset in the fourth quarter of 2018. See " Note 21—Subsequent Events (Unaudited) " for a discussion of the Company's amended services agreement with Google entered into on February 11, 2019. The Company's business is subject to certain risks and concentrations including dependence on third-party technology providers, exposure to risks associated with online commerce security and credit card fraud. Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash and cash equivalents and marketable securities. Cash and cash equivalents are maintained with financial institutions and are in excess of Federal Deposit Insurance Corporation insurance limits.
Property and Equipment	The Company capitalizes certain internal use software costs including external direct costs utilized in developing or obtaining the software and compensation for personnel directly associated with the development of the software. Capitalization of such costs begins when the preliminary project stage is complete and ceases when the project is substantially complete and ready for its intended purpose. Property and Equipment Property and equipment, including significant improvements, are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, or, in the case of leasehold improvements, the lease term, if shorter.
Business Combinations	Business Combinations The purchase price of each acquisition is attributed to the assets acquired and liabilities assumed based on their fair values at the date of acquisition, including identifiable intangible assets that either arise from a contractual or legal right or are separable from goodwill. The fair value of these intangible assets is based on valuations that use information and assumptions provided by management. The excess purchase price over the net tangible and identifiable intangible assets is recorded as goodwill and is assigned to the reporting unit(s) that is expected to benefit from the combination as of the acquisition date. In connection with certain business combinations, the Company has entered into contingent consideration arrangements that are determined to be part of the purchase price. Each of these arrangements is initially recorded at its fair value at the time of the acquisition and reflected at current fair value for each subsequent reporting period thereafter until settled. The contingent consideration arrangements are generally based upon earnings performance and/or operating metrics. The Company determines the fair value of the contingent consideration arrangements using probability-weighted analyses to determine the amounts of the gross liability, and, if the arrangement is long-term in nature, applying a discount rate that appropriately captures the risk associated with the obligation to determine the net amount reflected in the consolidated financial statements. Significant changes in forecasted earnings or operating metrics would result in a significantly higher or lower fair value measurement. The changes in the remeasured fair value of the contingent consideration arrangements during each reporting period, including the accretion of the discount, if applicable, are recognized in "General and administrative expense" in the accompanying consolidated statement of operations.
Goodwill and Indefinite-Lived Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets The Company assesses goodwill and indefinite-lived intangible assets for impairment annually as of October 1, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit or the fair value of an indefinite-lived intangible asset below its carrying value. When the Company elects to perform a qualitative assessment and concludes it is not more likely than not that the fair value of the reporting unit is less than its carrying value, no further assessment of that reporting unit's goodwill is necessary; otherwise, a quantitative assessment is performed and the fair value of the reporting unit is determined. If the carrying value of the reporting unit exceeds its fair value, an impairment equal to the excess is recorded. For the Company's annual goodwill test at October 1, 2018, a qualitative assessment of the MTCH, ANGI, Vimeo, College Humor Media and BlueCrew reporting units' goodwill was performed because the Company concluded it was more likely than not that the fair value of these reporting units was in excess of their respective carrying values. The primary fact ors that the Company considered in its qualitative assessment for each of these reporting units are described below: • MTCH's October 1, 2018 market capitalization of $15.7 billion exceeded its carrying value by approximately $15.1 billion and MTCH's strong operating performance. • ANGI's October 1, 2018 market capitalization of $10.7 billion exceeded its carrying value by approximately $9.6 billion and ANGI's strong operating performance. • The Company performed valuations of the Vimeo, College Humor Media and BlueCrew reporting units during 2018. These valuations were prepared primarily in connection with the issuance and/or settlement of equity grants that are denominated in the equity of these businesses. The valuations were prepared time proximate to, however, not as of, October 1, 2018. The fair value of each of these businesses was in excess of its October 1, 2018 carrying value. The Company tests goodwill for impairment when it concludes that it is more likely than not that there may be an impairment. For the Company's annual goodwill test at October 1, 2018, the Company quantitatively tested the Desktop and Mosaic Group reporting units (included in the Applications segment). The Company's quantitative test indicated that the fair value of these reporting units are in excess of their respective carrying values; therefore, the goodwill of these reporting units are not impaired. The Company's Dotdash, Ask Media Group and The Daily Beast reporting units have no goodwill. The aggregate goodwill balance for the reporting units for which the most recent estimate of fair value is less than 110% of their carrying values is approximately $265.1 million . The fair value of the Company's reporting units (except for MTCH and ANGI described above) is determined using both an income approach based on discounted cash flows ("DCF") and a market approach when it tests goodwill for impairment, either on an interim basis or annual basis as of October 1 each year. The Company uses the same approach in determining the fair value of its businesses in connection with its non-public subsidiary denominated stock-based compensation plans, which can be a significant factor in the decision to apply the qualitative screen. Determining fair value using a DCF analysis requires the exercise of significant judgment with respect to several items, including the amount and timing of expected future cash flows and appropriate discount rates. The expected cash flows used in the DCF analyses are based on the Company's most recent forecast and budget and, for years beyond the budget, the Company's estimates, which are based, in part, on forecasted growth rates. The discount rates used in the DCF analyses are intended to reflect the risks inherent in the expected future cash flows of the respective reporting units. Assumptions used in the DCF analyses, including the discount rate, are assessed based on each reporting unit's current results and forecasted future performance, as well as macroeconomic and industry specific factors. The discount rates used in the quantitative test for determining the fair value of the Company's reporting units ranged from 12.5% to 15% in 2018 and 12.5% to 17.5% in 2017. Determining fair value using a market approach considers multiples of financial metrics based on both acquisitions and trading multiples of a selected peer gr oup of companies. From the comparable companies, a representative market multiple is determined which is applied to financial metrics to estimate the fair value of a reporting unit. To determine a peer group of companies for our respective reporting units, we considered companies relevant in terms of consumer use, monetization model, margin and growth characteristics, and brand strength operating in their respective sectors. While a primary driver in the determination of the fair values of the Company's reporting units is the estimate of future revenue and profitability, the determination of fair value is based, in part, upon the Company's assessment of macroeconomic factors, industry and competitive dynamics and the strategies of its businesses in response to these factors. While the Company has the option to qualitatively assess whether it is more likely than not that the fair values of its indefinite-lived intangible assets are less than their carrying values, the Company's policy is to determine the fair value of each of its indefinite-lived intangible assets annually as of October 1. The Company determines the fair value of indefinite-lived intangible assets using an avoided royalty DCF valuation analysis. Significant judgments inherent in this analysis include the selection of appropriate royalty and discount rates and estimating the amount and timing of expected future cash flows. The discount rates used in the DCF analyses are intended to reflect the risks inherent in the expected future cash flows generated by the respective intangible assets. The royalty rates used in the DCF analyses are based upon an estimate of the royalty rates that a market participant would pay to license the Company's trade names and trademarks. Assumptions used in the avoided royalty DCF analyses, including the discount rate and royalty rate, are assessed annually based on the actual and projected cash flows related to the asset, as well as macroeconomic and industry specific factors. The discount rates used in the Company's annual indefinite-lived impairment assessment ranged from 10.5% to 35% in 2018 and 11% to 16% 2017, and the royalty rates used ranged from 0.75% to 8.0% in 2018 and 2% to 7% in 2017. The aggregate indefinite-lived intangible asset balance for which the most recent estimate of fair value is less than 110% of their carrying values is approximately $131.3 million . The 2018 annual assessment of goodwill did not identify any impairments. The 2018 annual assessment of indefinite-lived intangible assets identified impairment charges of $27.7 million and $1.1 million related to certain Desktop and College Humor Media indefinite-lived trade names, respectively. The indefinite-lived intangible asset impairment charge at Desktop was due to Google’s policy changes related to its Chrome browser which became effective on September 12, 2018 and have negatively impacted the distribution of our B2C downloadable desktop products. The impairment charge related to the B2C trade name was identified in our annual impairment assessment as of October 1, 2018 and reflects the projected reduction in profits and revenues and the resultant reduction in the assumed royalty rate from these policy changes. The impairment charges are included in "Amortization of intangibles" in the accompanying consolidated statement of operations. The 2017 annual assessments of goodwill and indefinite-lived intangible assets did not identify any impairments. While the 2016 annual assessment did not identify any material impairments, during the second quarter of 2016, the Company recorded an impairment charge equal to the entire $275.4 million at IAC Publishing. In connection with the Company's realignment of its reportable segments in the fourth quarter of 2018, $198.3 million and $77.0 million was allocated to the Dotdash and the Emerging & Other reportable segments, respectively, based upon their relative fair values as of October 1, 2018. In addition, amortization of intangibles was further impacted by the inclusion of impairment charges in 2016 of $9.0 million and $2.6 million related to certain Dictionary.com and Dotdash indefinite-lived trade names, respectively. The goodwill impairment charges at IAC Publishing was driven by the impact from the Google contract, traffic trends and monetization challenges and the corresponding impact on the then estimate of fair value. The expected cash flows used in the IAC Publishing DCF analysis were based on the Company's most recent forecast for the second half of 2016 and each of the years in the forecast period, which were updated to include the effects of the Google contract, traffic trends and monetization challenges and the cost savings from our restructuring efforts. For years beyond the forecast period, the Company's estimated cash flows were based on forecasted growth rates. The discount rate used in the DCF analysis reflected the risks inherent in the expected future cash flows of the IAC Publishing reporting unit. Determining fair value using a market approach considers multiples of financial metrics based on both acquisitions and trading multiples of a selected peer group of companies. From the comparable companies, a representative market multiple was determined which was applied to financial metrics to estimate the fair value of the IAC Publishing reporting unit. To determine a peer group of companies for IAC Publishing, we considered companies relevant in terms of business model, revenue profile, margin and growth characteristics and brand strength. The indefinite-lived intangible asset impairment charges related to certain trade names and trademarks and were due to reduced level of revenue and profits, which, in turn, also led to a reduction in the assumed royalty rates for these assets. The royalty rates used to value the trade names that were impaired ranged from 2% to 6% and the discount rate that was used reflected the risks inherent in the expected future cash flows of the trade names and trademarks. The impairment charge is included in "Amortization of intangibles" in the accompanying consolidated statement of operations. The Company’s operating segments are MTCH, ANGI, Vimeo, Dotdash and Applications, which are also reportable segments, and within its Emerging & Other reportable segment, Ask Media Group, BlueCrew, The Daily Beast, College Humor Media and IAC Films. The Company’s reporting units are consistent with its operating segments, with the exception of Desktop and Mosaic Group, which are separate reporting units within the Applications operating segment. Goodwill is tested for impairment at the reporting unit level.
Long-Lived Assets and Intangible Assets with Definite Lives	Long-Lived Assets and Intangible Assets with Definite Lives Long-lived assets, which consist of property and equipment and intangible assets with definite lives, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. The carrying value of a long-lived asset is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. If the carrying value is deemed not to be recoverable, an impairment loss is recorded equal to the amount by which the carrying value of the long-lived asset exceeds its fair value. Amortization of definite-lived intangible assets is computed either on a straight-line basis or based on the pattern in which the economic benefits of the asset will be realized.
Fair Value Measurements	Fair Value Measurements The Company categorizes its financial instruments measured at fair value into a fair value hierarchy that prioritizes the inputs used in pricing the asset or liability. The three levels of the fair value hierarchy are: • Level 1: Observable inputs obtained from independent sources, such as quoted market prices for identical assets and liabilities in active markets. • Level 2: Other inputs, which are observable directly or indirectly, such as quoted market prices for similar assets or liabilities in active markets, quoted market prices for identical or similar assets or liabilities in markets that are not active and inputs that are derived principally from or corroborated by observable market data. The fair values of the Company's Level 2 financial assets are primarily obtained from observable market prices for identical underlying securities that may not be actively traded. Certain of these securities may have different market prices from multiple market data sources, in which case an average market price is used. • Level 3: Unobservable inputs for which there is little or no market data and require the Company to develop its own assumptions, based on the best information available in the circumstances, about the assumptions market participants would use in pricing the assets or liabilities. See " Note 6—Financial Instruments " for a discussion of fair value measurements made using Level 3 inputs. The Company's non-financial assets, such as goodwill, intangible assets and property and equipment are adjusted to fair value only when an impairment is recognized. The Company's financial assets, comprising equity securities without readily determinable fair values, are adjusted to fair value when observable price changes are identified or an impairment is recognized. Such fair value measurements are based predominantly on Level 3 inputs.
Traffic Acquisition Costs	Traffic Acquisition Costs Traffic acquisition costs consist of (i) the amortization of fees paid to Apple and Google related to the distribution and the facilitation of in-app purchases and (ii) payments made to partners who distribute our business-to-business customized browser-based applications and who integrate our paid listings into their websites. These payments include amounts based on revenue share and other arrangements. The Company expenses these payments in the period incurred as a component of cost of revenue.
Advertising Costs	Advertising Costs Advertising costs are expensed in the period incurred (when the advertisement first runs for production costs that are initially capitalized) and represent online marketing, including fees paid to search engines, social media sites and third parties that distribute our B2C downloadable applications, offline marketing, which is primarily television advertising, and partner-related payments to those who direct traffic to the brands within our MTCH and ANGI segments. Advertising expense is $1.2 billion , $1.1 billion and $1.0 billion for the years ended December 31, 2018 , 2017 and 2016 , respectively. The Company capitalizes and amortizes the costs associated with certain distribution arrangements that require it to pay a fee per access point delivered. These access points are generally in the form of downloadable applications associated with our direct-to consumer operations. These fees are amortized over the estimated useful lives of the access points to the extent the Company can reasonably estimate a probable future economic benefit and the period over which such benefit will be realized (generally 18 months). Otherwise, the fees are charged to expense as incurred.
Legal Costs	Legal Costs Legal costs are expensed as incurred.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method, and deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying values of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided if it is determined that it is more likely than not that the deferred tax asset will not be realized. The Company records interest, net of any applicable related income tax benefit, on potential income tax contingencies as a component of income tax expense. The Company evaluates and accounts for uncertain tax positions using a two-step approach. Recognition (step one) occurs when the Company concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustainable upon examination. Measurement (step two) determines the amount of benefit that is greater than 50% likely to be realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. De-recognition of a tax position that was previously recognized would occur when the Company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act (the "Tax Act"). The Tax Act imposes a new minimum tax on global intangible low-taxed income ("GILTI") earned by foreign subsidiaries beginning in 2018. The FASB Staff Q&A, Topic 740 No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity may make an accounting policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred. The Company elects to recognize the tax on GILTI as a period expense in the period the tax is incurred.
Earnings Per Share	Earnings Per Share Basic earnings per share is computed by dividing net earnings attributable to IAC shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share reflects the potential dilution that could occur if stock options and other commitments to issue common stock were exercised or equity awards vested resulting in the issuance of common stock that could share in the earnings of the Company.
Foreign Currency Translation and Transaction Gains and Losses	Foreign Currency Translation and Transaction Gains and Losses The financial position and operating results of foreign entities whose primary economic environment is based on their local currency are consolidated using the local currency as the functional currency. These local currency assets and liabilities are translated at the rates of exchange as of the balance sheet date, and local currency revenue and expenses of these operations are translated at average rates of exchange during the period. Translation gains and losses are included in accumulated other comprehensive income as a component of shareholders' equity. Transaction gains and losses resulting from assets and liabilities denominated in a currency other than the functional currency are included in the consolidated statement of operations as a component of other income (expense), net. See " Note 17—Consolidated Financial Statement Details " for additional information regarding foreign currency exchange gains and losses. Translation gains and losses relating to foreign entities that are liquidated or substantially liquidated are reclassified out of accumulated other comprehensive income (loss) into earnings.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation is measured at the grant date based on the fair value of the award and is generally expensed over the requisite service period.
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests Noncontrolling interests in the consolidated subsidiaries of the Company are ordinarily reported on the consolidated balance sheet within shareholders' equity, separately from the Company's equity. However, securities that are redeemable at the option of the holder and not solely within the control of the issuer must be classified outside of shareholders' equity. Accordingly, all noncontrolling interests that are redeemable at the option of the holder are presented outside of shareholders' equity in the accompanying consolidated balance sheet. In connection with the acquisition of certain subsidiaries, management of these businesses has retained an ownership interest. The Company is party to fair value put and call arrangements with respect to these interests. These put and call arrangements allow management of these businesses to require the Company to purchase their interests or allow the Company to acquire such interests at fair value, respectively. The put arrangements do not meet the definition of a derivative instrument as the put agreements do not provide for net settlement. These put and call arrangements become exercisable by the Company and the counter-party at various dates in the future. Two of these arrangements were exercised during both the years ended December 31, 2018 and 2017 and one of these arrangements was exercised during the year ended December 31, 2016 . These put arrangements are exercisable by the counter-party outside the control of the Company. Accordingly, to the extent that the fair value of these interests exceeds the value determined by normal noncontrolling interest accounting, the value of such interests is adjusted to fair value with a corresponding adjustment to additional paid-in capital. During the years ended December 31, 2018 , 2017 and 2016 , the Company recorded adjustments of $4.1 million , $6.3 million and $7.9 million , respectively, to increase these interests to fair value. Fair value determinations require high levels of judgment and are based on various valuation techniques, including market comparables and discounted cash flow projections.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements adopted by the Company ASU No. 2014-09, Revenue from Contracts with Customers In May 2014, the FASB issued ASU No. 2014-09, which superseded nearly all previous revenue recognition guidance. The Company adopted ASU No. 2014-09 effective January 1, 2018 using the modified retrospective transition method for open contracts as of the date of initial application. The cumulative effect to the Company's retained earnings at January 1, 2018 was an increase of $40.2 million , of which $3.4 million was related to the noncontrolling interest in ANGI; the adjustment to retained earnings was principally related to the Company’s ANGI and Applications segments. • Within ANGI, the effect of the adoption of ASU No. 2014-09 is that commissions paid to employees pursuant to certain sales incentive programs, which represent the incremental direct costs of obtaining a service professional contract, are now capitalized and amortized over the estimated life of a service professional (also referred to as the estimated customer relationship period). These costs were expensed as incurred prior to January 1, 2018. The cumulative effect of the adoption of ASU No. 2014-09 was the establishment of a current and non-current asset for capitalized sales commissions of $29.7 million and $4.2 million , respectively, and a related deferred tax liability of $8.0 million , resulting in a net increase to retained earnings of $25.9 million on January 1, 2018. • Within Applications, the primary effect of the adoption of ASU No. 2014-09 is to accelerate the recognition of the portion of the revenue of certain desktop applications sold by SlimWare that qualifies as functional intellectual property ("functional IP") under ASU No. 2014-09. This revenue was previously deferred and recognized over the applicable subscription term. The cumulative effect of the adoption of ASU No. 2014-09 for SlimWare was a reduction in deferred revenue of $20.3 million and the establishment of a deferred tax liability of $4.9 million , resulting in a net increase to retained earnings of $15.5 million on January 1, 2018. The Company's disaggregated revenue disclosures are presented in " Note 12—Segment Information ." The following table presents the impact of the adoption of ASU No. 2014-09 by segment under Accounting Standards Codification ("ASC") 606, Revenue from Contracts with Customers , as reported, and ASC 605, Revenue Recognition , for the year ended December 31, 2018. Under ASC 606 Under ASC 605 Effect of adoption of ASU No. 2014-09 (In thousands) Revenue by segment: Match Group $ 1,729,850 $ 1,729,850 $ — ANGI Homeservices 1,132,241 1,132,241 — Vimeo 159,641 160,931 (1,290 ) Dotdash 130,991 130,991 — Applications 582,287 581,492 795 Emerging & Other 528,250 528,250 — Inter-segment eliminations (368 ) (368 ) — Total $ 4,262,892 $ 4,263,387 $ (495 ) Operating costs and expenses by segment: Match Group $ 1,176,556 $ 1,176,556 $ — ANGI Homeservices 1,068,335 1,073,275 (4,940 ) Vimeo 195,235 196,212 (977 ) Dotdash 112,213 112,213 — Applications 487,453 484,644 2,809 Emerging & Other 498,286 498,286 — Corporate 159,675 159,675 — Total $ 3,697,753 $ 3,700,861 $ (3,108 ) Operating income (loss) by segment: Match Group $ 553,294 $ 553,294 $ — ANGI Homeservices 63,906 58,966 4,940 Vimeo (35,594 ) (35,281 ) (313 ) Dotdash 18,778 18,778 — Applications 94,834 96,848 (2,014 ) Emerging & Other 29,964 29,964 — Corporate (160,043 ) (160,043 ) — Total $ 565,139 $ 562,526 $ 2,613 Net earnings $ 757,747 $ 755,741 $ 2,006 ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU No. 2016-01, which updates certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Under ASU No. 2016-01, equity securities, other than those of our consolidated subsidiaries and those accounted for under the equity method, will be measured at fair value with changes in fair value recognized in the statement of operations each reporting period. ASU No. 2016-01 is effective for reporting periods beginning after December 15, 2017. There was no cumulative impact to the Company's consolidated financial statements upon adoption of ASU No. 2016-01 on January 1, 2018. The adoption of ASU No. 2016-01 increases the volatility of the Company's other income (expense), net as a result of the remeasurement of these instruments. For the year ended December 31, 2018, other income (expense), net includes net unrealized gains related to certain equity securities that were adjusted to fair value in the second quarter of 2018 in accordance with ASU No. 2016-01 of $126.4 million . See " Note 6—Financial Instruments " for additional information. ASU No. 2016-18, Restricted Cash In November 2016, the FASB issued ASU No. 2016-18, which requires companies to explain the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. Therefore, amounts generally described as restricted cash or restricted cash equivalents are combined with unrestricted cash and cash equivalents when reconciling the beginning and end of period balances on the statement of cash flows. ASU No. 2016-18 also requires companies to disclose the nature of their restricted cash and restricted cash equivalents balances. Additionally, when cash, cash equivalents, restricted cash, and restricted cash equivalents are presented within different captions on the balance sheet, a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet is required. ASU No. 2016-18 is effective for reporting periods beginning after December 15, 2017. The Company's adoption of ASU No. 2016-18 effective January 1, 2018, on a retrospective basis, did not have a material effect on its consolidated financial statements. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheet to the total amounts shown in the consolidated statement of cash flows: December 31, 2018 December 31, 2017 December 31, 2016 December 31, 2015 (In thousands) Cash and cash equivalents $ 2,131,632 $ 1,630,809 $ 1,329,187 $ 1,481,447 Restricted cash included in other current assets 1,633 2,873 20,464 126 Restricted cash included in other assets 420 — 10,548 20,100 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 2,133,685 $ 1,633,682 $ 1,360,199 $ 1,501,673 Restricted cash at December 31, 2018 primarily consists of a cash collateralized letter of credit and a deposit related to corporate credit cards. Restricted cash at December 31, 2017 primarily supports a letter of credit to a supplier, which was released to the Company in the second quarter of 2018. Restricted cash at December 31, 2016 primarily included funds held in escrow for the redemption and repurchase of IAC Senior Notes and the MyHammer tender offer. In the first quarter of 2017, the Senior Notes were redeemed and repurchased and the funds held in escrow for the MyHammer tender offer were returned to the Company. Restricted cash at December 31, 2015 primarily includes the repurchase of IAC Senior Notes. ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued ASU No. 2018-15, which clarifies the accounting for implementation costs in a cloud computing arrangement that is a services contract to follow the internal-use software guidance of ASC 350-40, Intangibles - Goodwill and Other, Internal-use Software . The provisions of ASU No. 2018-15 are effective for reporting periods beginning after December 15, 2019, including interim periods and early adoption is permitted, including adoption in any interim period. The provisions of ASU No. 2018-15 may be adopted prospectively to all implementation costs incurred after the date of adoption or retrospectively. The Company early adopted the provisions of ASU No. 2018-15 on October 1, 2018 prospectively and the adoption of this standard did not have material impact on its consolidated financial statements. ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU No. 2018-07, which largely aligns the measurement and classification guidance for share-based payments granted to non-employees with the guidance for share-based payments granted to employees. The new guidance supersedes Subtopic 505-50, Equity - Equity-Based payments to Nonemployees . ASU No. 2018-07 is effective for reporting periods beginning after December 15, 2018, with early adoption permitted. The Company adopted ASU No. 2018-07 effective April 1, 2018 and its adoption did not have a material effect on its consolidated financial statements. The effect of the adoption of ASU No. 2018-07 will be to minimize the volatility of expense related to stock-based awards to non-employees in the future. Accounting Pronouncement not yet adopted by the Company ASU No. 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU No. 2016-02, which supersedes existing guidance on accounting for leases and generally requires all leases to be recognized in the statement of financial position. The provisions of ASU No. 2016-02 are effective for reporting periods beginning after December 15, 2018. The Company will adopt the new lease guidance effective January 1, 2019. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which provides the option of an additional transition method that allows entities to initially apply the new lease guidance at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company expects to implement the transition method option provided by ASU No. 2018-11. The Company is not a lessor, has no capitalized leases and does not expect to enter into any capitalized leases prior to the adoption of ASU No. 2016-02. Accordingly, the Company does not expect the amount or classification of rent expense in its statement of operations to be affected by the adoption of ASU No. 2016-02. The primary effect of the adoption of ASU No. 2016-02 will be the recognition of a right of use asset and related lease liability to reflect the Company's rights and obligations under its operating leases. The Company will also be required to provide the additional disclosures stipulated in ASU No. 2016-02. The adoption of ASU No. 2016-02 will not have an impact on the leverage calculation set forth in any of the agreements governing the outstanding debt of the Company or its MTCH and ANGI subsidiaries, or our credit agreement or the credit agreement of MTCH and ANGI because, in each circumstance, the leverage calculations are not affected by the lease liability that will be recorded upon adoption of the new standard. While the Company's evaluation of the impact of the adoption of ASU No. 2016-02 on its consolidated financial statements continues, outlined below is a summary of the status of the Company's progress: • the Company has selected a software solution to implement ASU No. 2016-02; • the Company has input lease summaries into the software solution; • the Company is assessing the other inputs required in connection with the adoption of ASU No. 2016-02; and • the Company is developing its accounting policy, procedures and internal controls related to the new standard. Development of the selected software solution by the third-party vendor is ongoing. While significant progress has been made, certain key deliverables remain, which the Company expects to be delivered in March 2019. The Company's ability to adopt ASU No. 2016-02 in an efficient and effective manner is contingent upon the delivery and testing of these remaining deliverables. The Company has been able to develop a preliminary estimate of the impact of the adoption of ASU No. 2016-02 through the use of the third-party software solution, supplemented by our user acceptance testing. This preliminary estimate is that a $160 million right of use asset and related lease liability will be recognized on the Company's consolidated balance sheet upon adoption. The Company does not expect a material impact on its results of operations or cash flows.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives of Property and Equipment	Asset Category Estimated Useful Lives Buildings and leasehold improvements 3 to 39 Years Computer equipment and capitalized software 2 to 3 Years Furniture and other equipment 3 to 12 Years December 31, 2018 2017 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 249,026 $ 246,038 Computer equipment and capitalized software 229,083 218,529 Furniture and other equipment 86,694 88,930 Projects in progress 29,204 19,094 Land 11,591 14,390 Property and equipment 605,598 586,981 Accumulated depreciation and amortization (286,798 ) (271,811 ) Property and equipment, net of accumulated depreciation and amortization $ 318,800 $ 315,170
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following table presents the impact of the adoption of ASU No. 2014-09 by segment under Accounting Standards Codification ("ASC") 606, Revenue from Contracts with Customers , as reported, and ASC 605, Revenue Recognition , for the year ended December 31, 2018. Under ASC 606 Under ASC 605 Effect of adoption of ASU No. 2014-09 (In thousands) Revenue by segment: Match Group $ 1,729,850 $ 1,729,850 $ — ANGI Homeservices 1,132,241 1,132,241 — Vimeo 159,641 160,931 (1,290 ) Dotdash 130,991 130,991 — Applications 582,287 581,492 795 Emerging & Other 528,250 528,250 — Inter-segment eliminations (368 ) (368 ) — Total $ 4,262,892 $ 4,263,387 $ (495 ) Operating costs and expenses by segment: Match Group $ 1,176,556 $ 1,176,556 $ — ANGI Homeservices 1,068,335 1,073,275 (4,940 ) Vimeo 195,235 196,212 (977 ) Dotdash 112,213 112,213 — Applications 487,453 484,644 2,809 Emerging & Other 498,286 498,286 — Corporate 159,675 159,675 — Total $ 3,697,753 $ 3,700,861 $ (3,108 ) Operating income (loss) by segment: Match Group $ 553,294 $ 553,294 $ — ANGI Homeservices 63,906 58,966 4,940 Vimeo (35,594 ) (35,281 ) (313 ) Dotdash 18,778 18,778 — Applications 94,834 96,848 (2,014 ) Emerging & Other 29,964 29,964 — Corporate (160,043 ) (160,043 ) — Total $ 565,139 $ 562,526 $ 2,613 Net earnings $ 757,747 $ 755,741 $ 2,006
Schedule of Cash, Cash Equivalents, and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheet to the total amounts shown in the consolidated statement of cash flows: December 31, 2018 December 31, 2017 December 31, 2016 December 31, 2015 (In thousands) Cash and cash equivalents $ 2,131,632 $ 1,630,809 $ 1,329,187 $ 1,481,447 Restricted cash included in other current assets 1,633 2,873 20,464 126 Restricted cash included in other assets 420 — 10,548 20,100 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 2,133,685 $ 1,633,682 $ 1,360,199 $ 1,501,673
Schedule of Cash, Cash Equivalents, and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheet to the total amounts shown in the consolidated statement of cash flows: December 31, 2018 December 31, 2017 December 31, 2016 December 31, 2015 (In thousands) Cash and cash equivalents $ 2,131,632 $ 1,630,809 $ 1,329,187 $ 1,481,447 Restricted cash included in other current assets 1,633 2,873 20,464 126 Restricted cash included in other assets 420 — 10,548 20,100 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 2,133,685 $ 1,633,682 $ 1,360,199 $ 1,501,673

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income before Income Taxes	U.S. and foreign earnings (loss) before income taxes and noncontrolling interests are as follows: Years Ended December 31, 2018 2017 2016 (In thousands) U.S. $ 630,417 $ (52,606 ) $ (248,433 ) Foreign 131,141 119,564 167,348 Total $ 761,558 $ 66,958 $ (81,085 )
Schedule of Components of Income Tax Expense (Benefit)	The components of the income tax provision (benefit) are as follows: Years Ended December 31, 2018 2017 2016 (In thousands) Current income tax provision (benefit): Federal $ (2,849 ) $ (31,844 ) $ 23,343 State 2,569 1,964 3,662 Foreign 38,770 24,108 27,242 Current income tax provision (benefit) 38,490 (5,772 ) 54,247 Deferred income tax provision (benefit): Federal (21,792 ) (255,477 ) (100,798 ) State 172 (28,364 ) (9,518 ) Foreign (13,059 ) (1,437 ) (8,865 ) Deferred income tax benefit (34,679 ) (285,278 ) (119,181 ) Income tax provision (benefit) $ 3,811 $ (291,050 ) $ (64,934 )
Schedule of Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets	Income taxes receivable (payable) and deferred tax assets (liabilities) are included in the following captions in the accompanying consolidated balance sheet at December 31, 2018 and 2017 : December 31, 2018 2017 (In thousands) Income taxes receivable (payable): Other current assets $ 10,132 $ 33,239 Other non-current assets 11,401 1,949 Accrued expenses and other current liabilities (12,745 ) (11,798 ) Income taxes payable (37,584 ) (25,624 ) Net income taxes payable $ (28,796 ) $ (2,234 ) Deferred tax assets (liabilities): Other non-current assets $ 64,786 $ 66,321 Deferred income taxes (23,600 ) (35,070 ) Net deferred tax assets $ 41,186 $ 31,251
Schedule of Deferred Tax Assets and Liabilities	The tax effects of cumulative temporary differences that give rise to significant deferred tax assets and deferred tax liabilities are presented below. The valuation allowance relates to deferred tax assets for which it is more likely than not that the tax benefit will not be realized. December 31, 2018 2017 (In thousands) Deferred tax assets: Accrued expenses $ 23,525 $ 22,234 NOL carryforwards 291,639 292,812 Tax credit carryforwards 89,397 78,715 Stock-based compensation 82,698 77,976 Other 30,106 42,331 Total deferred tax assets 517,365 514,068 Less valuation allowance (115,853 ) (132,598 ) Net deferred tax assets 401,512 381,470 Deferred tax liabilities: Investment in subsidiaries (238,650 ) (247,167 ) Intangibles (77,669 ) (87,811 ) Fair value investment (22,927 ) — Other (21,080 ) (15,241 ) Total deferred tax liabilities (360,326 ) (350,219 ) Net deferred tax assets $ 41,186 $ 31,251
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the income tax provision (benefit) to the amounts computed by applying the statutory federal income tax rate to earnings before income taxes is shown as follows: Years Ended December 31, 2018 2017 2016 (In thousands) Income tax provision (benefit) at the federal statutory rate of 21% (35% for 2017 and 2016) $ 159,927 $ 23,435 $ (28,446 ) State income taxes, net of effect of federal tax benefit 14,887 86 (3,880 ) Stock-based compensation (129,654 ) (358,901 ) 3,998 Realization of certain deferred tax assets (13,200 ) (3,133 ) — Transition tax (9,190 ) 62,667 — Deferred tax adjustment for enacted changes in tax laws and rates (7,488 ) 705 (4,594 ) Research credit (4,023 ) (5,304 ) (2,231 ) Foreign income taxed at a different statutory tax rate (3,206 ) (14,725 ) (27,115 ) Non-taxable sale and non-deductible goodwill associated with ShoeBuy — — (13,142 ) Goodwill impairment of Dotdash and Emerging & Other — — 10,649 Non-deductible impairments for certain cost method investments — 2,669 3,489 Other, net (4,242 ) 1,451 (3,662 ) Income tax provision (benefit) $ 3,811 $ (291,050 ) $ (64,934 )
Schedule of Income Tax Contingencies	A reconciliation of the beginning and ending amount of unrecognized tax benefits, including penalties but excluding interest, is as follows: December 31, 2018 2017 2016 (In thousands) Balance at January 1 $ 36,732 $ 38,372 $ 40,808 Additions based on tax positions related to the current year 10,334 2,050 2,033 Additions for tax positions of prior years 4,716 1,994 2,676 Reductions for tax positions of prior years (400 ) (3,761 ) (743 ) Settlements — — (5,107 ) Expiration of applicable statutes of limitations (2,507 ) (1,923 ) (1,295 ) Balance at December 31 $ 48,875 $ 36,732 $ 38,372

BUSINESS COMBINATION (Tables)

BUSINESS COMBINATION (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Purchase Price	The table below summarizes the purchase price: Angie's List (In thousands) Class A common stock $ 763,684 Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock 1,913 Fair value of vested and pro rata portion of unvested stock options attributable to pre-combination services 11,749 Fair value of the pro rata portion of unvested restricted stock units attributable to pre-combination services 4,038 Total purchase price $ 781,384 A summary of the costs incurred, payments made and the related accrual is presented below. Years Ended December 31, 2018 2017 (In thousands) Transaction and integration related costs $ 3,584 $ 44,101 Stock-based compensation expense 70,645 122,066 Total $ 74,229 $ 166,167 December 31, 2018 2017 (In thousands) Accrual as of January 1 $ 8,480 $ — Costs incurred 3,584 44,101 Payments made (12,064 ) (35,621 ) Accrual as of December 31 $ — $ 8,480 The costs are allocated as follows in the accompanying consolidated statement of operations: Year Ended December 31, 2018 Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense — 2,161 2,161 General and administrative expense 3,584 61,010 64,594 Product development expense — 7,474 7,474 Total $ 3,584 $ 70,645 $ 74,229 Year Ended December 31, 2017 Transaction and Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense 7,430 24,416 31,846 General and administrative expense 36,120 83,420 119,540 Product development expense 551 14,230 14,781 Total $ 44,101 $ 122,066 $ 166,167
Schedule of Preliminary Estimated Fair Value of Assets Acquired and Liabilities Assumed	The table below summarizes the fair values of the assets acquired and liabilities assumed at the date of combination: Angie's List (In thousands) Cash and cash equivalents $ 44,270 Other current assets 11,280 Property and equipment 16,341 Goodwill 543,674 Intangible assets 317,300 Total assets 932,865 Deferred revenue (32,595 ) Other current liabilities (46,150 ) Long-term debt—related party (61,498 ) Deferred income taxes (9,833 ) Other long-term liabilities (1,405 ) Net assets acquired $ 781,384
Schedule of Preliminary Estimated Fair Value of Intangible Assets Acquired	The fair values of the identifiable intangible assets acquired at the date of combination are as follows: Angie's List (In thousands) Weighted-Average Useful Life (Years) Indefinite-lived trade name and trademarks $ 137,000 Indefinite Service professionals 90,500 3 Developed technology 63,900 6 Memberships 15,900 3 User base 10,000 1 Total identifiable intangible assets acquired $ 317,300
Schedule of Pro Forma Financial Information	Years Ended December 31, 2017 2016 (In thousands, except per share data) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to ANGI Homeservices Inc. shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders $ 4.27 $ (1.79 )

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Intangible Assets, Net	Goodwill and intangible assets, net are as follows: December 31, 2018 2017 (In thousands) Goodwill $ 2,726,859 $ 2,559,066 Intangible assets with indefinite lives 458,104 459,143 Intangible assets with definite lives, net of accumulated amortization 173,318 204,594 Total goodwill and intangible assets, net $ 3,358,281 $ 3,222,803
Schedule of Goodwill by Reporting Unit	The following table presents the balance of goodwill by reportable segment, including the changes in the carrying value of goodwill, for the year ended December 31, 2018 : Balance at Additions (Deductions) Transfers In/(Out) Foreign Balance at (In thousands) Match Group $ 1,247,899 $ 11,187 $ — $ — $ (14,073 ) $ 1,245,013 ANGI Homeservices 768,317 142,768 (14,373 ) — (3,912 ) 892,800 Vimeo 77,303 — (151 ) — — 77,152 Applications: Desktop 265,146 — — — — 265,146 Mosaic Group 182,096 50,784 — 7,323 (457 ) 239,746 Total Applications 447,242 50,784 — 7,323 (457 ) 504,892 Emerging & Other 18,305 3,684 (7,664 ) (7,323 ) — 7,002 Total $ 2,559,066 $ 208,423 $ (22,188 ) $ — $ (18,442 ) $ 2,726,859 The following table presents the balance of goodwill by reportable segment, including the changes in the carrying value of goodwill, for the year ended December 31, 2017 : Balance at Additions (Deductions) Foreign Balance at (In thousands) Match Group $ 1,206,538 $ 255 $ — $ 41,106 $ 1,247,899 ANGI Homeservices 170,611 590,772 — 6,934 768,317 Vimeo 9,649 67,654 — — 77,303 Applications: Desktop 265,146 — — — 265,146 Mosaic Group 182,096 — — — 182,096 Total Applications 447,242 — — — 447,242 Emerging & Other 90,012 2,715 (74,430 ) 8 18,305 Total $ 1,924,052 $ 661,396 $ (74,430 ) $ 48,048 $ 2,559,066
Schedule of Intangible Assets with Definite Lives	Intangible assets with indefinite lives are trade names and trademarks acquired in various acquisitions. At December 31, 2018 and 2017 , intangible assets with definite lives are as follows: December 31, 2018 Gross Accumulated Net Weighted-Average (In thousands) Technology $ 143,303 $ (53,199 ) $ 90,104 4.7 Service professional and contractor relationships 99,528 (44,674 ) 54,854 2.9 Customer lists and user base 30,099 (15,126 ) 14,973 2.9 Memberships 15,900 (6,640 ) 9,260 3.0 Trade names 12,393 (9,393 ) 3,000 3.3 Other 8,500 (7,373 ) 1,127 4.8 Total $ 309,723 $ (136,405 ) $ 173,318 3.8 December 31, 2017 Gross Accumulated Net Weighted-Average (In thousands) Technology $ 115,200 $ (37,357 ) $ 77,843 4.8 Service professional and contractor relationships 99,497 (11,452 ) 88,045 3.0 Customer lists and user base 23,468 (5,401 ) 18,067 2.2 Memberships 15,900 (1,340 ) 14,560 3.0 Trade names 16,986 (13,634 ) 3,352 2.6 Other 8,500 (5,773 ) 2,727 4.8 Total $ 279,551 $ (74,957 ) $ 204,594 3.7
Schedule of Expected Amortization of Intangible Assets	At December 31, 2018 , amortization of intangible assets with definite lives for each of the next five years and thereafter is estimated to be as follows: Years Ending December 31, (In thousands) 2019 $ 71,155 2020 51,916 2021 19,433 2022 16,310 2023 10,239 Thereafter 4,265 Total $ 173,318

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Marketable Securities	At December 31, 2018 and 2017, the fair value of marketable securities are as follows: December 31, 2018 2017 (In thousands) Available-for-sale marketable debt securities $ 123,246 $ 4,995 Marketable equity security 419 — Total marketable securities $ 123,665 $ 4,995
Schedule of Current Available-for-sale Marketable Securities	At December 31, 2017 , current available-for-sale marketable debt securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 4,995 $ — $ — $ 4,995 Total available-for-sale marketable debt securities $ 4,995 $ — $ — $ 4,995 At December 31, 2018 , current available-for-sale marketable debt securities are as follows: Amortized Gross Gross Fair Value (In thousands) Treasury discount notes $ 112,291 $ 3 $ (3 ) $ 112,291 Commercial paper 10,955 — — 10,955 Total available-for-sale marketable debt securities $ 123,246 $ 3 $ (3 ) $ 123,246
Schedule of Proceeds from Maturities and Sales of Current Available-for-sale Marketable Securities	The following table presents the proceeds from maturities and sales of available-for-sale marketable debt securities and the related gross realized gains: December 31, 2018 2017 2016 (In thousands) Proceeds from maturities and sales of available-for-sale marketable debt securities $ 333,600 $ 114,350 $ 279,485 Gross realized gains — — 3,556
Schedule of Long-term Investments	Long-term investments consist of: December 31, 2018 2017 (In thousands) Equity securities without readily determinable fair values $ 235,055 $ — Equity method investments — 1,559 Cost method investments — 63,418 Total long-term investments $ 235,055 $ 64,977
Schedule of Realized and Unrealized Gains (Losses) on Investments	The following table presents a summary of realized and unrealized gains and losses recorded in other income (expense), net, as adjustments to the carrying value of equity securities without readily determinable fair values held as of December 31, 2018. The gross unrealized gains principally relate to the Company's remaining investments in an investee following the sale of a portion of the Company's investment during the second quarter of 2018. Year Ended December 31, 2018 (In thousands) Upward adjustments (gross unrealized gains) $ 128,986 Downward adjustments including impairments (gross unrealized losses) (4,931 ) Total $ 124,055 Realized and unrealized gains and losses for the Company's marketable equity security and investments without readily determinable fair values for the year ended December 31, 2018 are as follows: Year Ended December 31, 2018 (In thousands) Realized gains, net, for equity securities sold $ 27,874 Unrealized gains, net, on equity securities held 124,170 Total gains recognized, net, in other income (expense), net $ 152,044
Schedule of Financial Instruments Measured at Fair Value on Recurring Basis	The following tables present the Company's financial instruments that are measured at fair value on a recurring basis: December 31, 2018 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 880,815 $ — $ — $ 880,815 Treasury discount notes — 561,733 — 561,733 Commercial paper — 162,417 — 162,417 Time deposits — 90,036 — 90,036 Marketable securities: Treasury discount notes — 112,291 — 112,291 Commercial paper — 10,955 — 10,955 Marketable equity security 419 — — 419 Total $ 881,234 $ 937,432 $ — $ 1,818,666 Liabilities: Contingent consideration arrangements $ — $ — $ (28,631 ) $ (28,631 ) December 31, 2017 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 780,425 $ — $ — $ 780,425 Commercial paper — 215,325 — 215,325 Treasury discount notes — 100,457 — 100,457 Time deposits — 60,000 — 60,000 Certificates of deposit — 6,195 — 6,195 Marketable securities: Commercial paper — 4,995 — 4,995 Total $ 780,425 $ 386,972 $ — $ 1,167,397 Liabilities: Contingent consideration arrangements $ — $ — $ (2,647 ) $ (2,647 )
Schedule of Unobservable Inputs in Fair Value Measurement	The Company's financial instruments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3) are its contingent consideration arrangements. Contingent Consideration Arrangements Years Ended December 31, 2018 2017 (In thousands) Balance at January 1 $ (2,647 ) $ (33,871 ) Total net (losses) gains: Included in earnings: Fair value adjustments (1,456 ) (5,801 ) Included in other comprehensive income (loss) 45 (1,404 ) Fair value at date of acquisition (25,521 ) — Settlements 948 38,429 Balance at December 31 $ (28,631 ) $ (2,647 )
Schedule of Carrying Value and the Fair Value of Financial Instruments Measured at Fair Value Only for Disclosure Purposes	The following table presents the carrying value and the fair value of financial instruments measured at fair value only for disclosure purposes: December 31, 2018 December 31, 2017 Carrying Fair Carrying Fair (In thousands) Current portion of long-term debt $ (13,750 ) $ (12,753 ) $ (13,750 ) $ (13,802 ) Long-term debt, net (a) (2,245,548 ) (2,460,204 ) (1,979,469 ) (2,168,108 ) _________________ (a) At December 31, 2018 and 2017, the carrying value of long-term debt, net includes unamortized original issue discount and debt issuance costs of $88.9 million and $109.1 million , respectively .

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt consists of: December 31, 2018 2017 (In thousands) MTCH Debt: MTCH Term Loan due November 16, 2022 $ 425,000 $ 425,000 MTCH Credit Facility due December 7, 2023 260,000 — 6.375% Senior Notes due June 1, 2024 (the "6.375% MTCH Senior Notes"); interest payable each June 1 and December 1 400,000 400,000 5.00% Senior Notes due December 15, 2027 (the "5.00% MTCH Senior Notes"); interest payable each June 15 and December 15 450,000 450,000 Total MTCH long-term debt 1,535,000 1,275,000 Less: unamortized original issue discount 7,352 8,668 Less: unamortized debt issuance costs 11,737 13,636 Total MTCH debt, net 1,515,911 1,252,696 ANGI Debt: ANGI Term Loan due November 5, 2023 261,250 275,000 Less: current portion of ANGI Term Loan 13,750 13,750 Less: unamortized debt issuance costs 2,529 2,938 Total ANGI debt, net 244,971 258,312 IAC Debt: 0.875% Exchangeable Senior Notes due October 1, 2022 (the "Exchangeable Notes"); interest payable each April 1 and October 1 517,500 517,500 4.75% Senior Notes due December 15, 2022 (the "4.75% Senior Notes"); interest payable each June 15 and December 15 34,489 34,859 Total IAC long-term debt 551,989 552,359 Less: unamortized original issue discount 54,025 67,158 Less: unamortized debt issuance costs 13,298 16,740 Total IAC debt, net 484,666 468,461 Total long-term debt, net $ 2,245,548 $ 1,979,469
Schedule of Debt Instrument Redemption	Thereafter, these notes may be redeemed at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed during the twelve-month period beginning on December 15 of the years indicated below: Year Percentage 2022 102.500 % 2023 101.667 % 2024 100.833 % 2025 and thereafter 100.000 % Thereafter, these notes may be redeemed at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed during the twelve-month period beginning on June 1 of the years indicated below: Year Percentage 2019 104.781 % 2020 103.188 % 2021 101.594 % 2022 and thereafter 100.000 %
Schedule of Aggregate Contractual Maturities of Long-term Debt	Long-term debt maturities: Years Ending December 31, (In thousands) 2019 $ 13,750 2020 13,750 2021 13,750 2022 1,004,489 2023 452,500 2024 400,000 2027 450,000 Total 2,348,239 Less: current portion of long-term debt 13,750 Less: unamortized original issue discount 61,377 Less: unamortized debt issuance costs 27,564 Total long-term debt, net $ 2,245,548

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	The following tables present the components of accumulated other comprehensive (loss) income and items reclassified out of accumulated other comprehensive loss into earnings: Year Ended December 31, 2018 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive Loss (In thousands) Balance at January 1 $ (103,568 ) $ — $ (103,568 ) Other comprehensive (loss) income before reclassifications (25,106 ) 4 (25,102 ) Amounts reclassified to earnings (52 ) — (52 ) Net current period other comprehensive (loss) income (25,158 ) 4 (25,154 ) Balance at December 31 $ (128,726 ) $ 4 $ (128,722 ) Year Ended December 31, 2017 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive (Loss) Income (In thousands) Balance at January 1 $ (170,149 ) $ 4,026 $ (166,123 ) Other comprehensive income before reclassifications 65,908 7 65,915 Amounts reclassified to earnings 673 (4,033 ) (3,360 ) Net current period other comprehensive income (loss) 66,581 (4,026 ) 62,555 Balance at December 31 $ (103,568 ) $ — $ (103,568 ) Year Ended December 31, 2016 Foreign Currency Translation Adjustment Unrealized Gains On Available-For-Sale Securities Accumulated Other Comprehensive (Loss) Income (In thousands) Balance at January 1 $ (154,645 ) $ 2,542 $ (152,103 ) Other comprehensive (loss) income before reclassifications, net of tax benefit of $0.7 million related to unrealized losses on available-for-sale securities (46,943 ) 4,855 (42,088 ) Amounts reclassified to earnings 9,850 (2,913 ) 6,937 Net current period other comprehensive (loss) income (37,093 ) 1,942 (35,151 ) Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO 21,589 (458 ) 21,131 Balance at December 31 $ (170,149 ) $ 4,026 $ (166,123 )

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings per Share	The following table sets forth the computation of basic and diluted earnings (loss) per share attributable to IAC shareholders: Years Ended December 31, 2018 2017 2016 Basic Diluted Basic Diluted Basic Diluted (In thousands, except per share data) Numerator: Net earnings (loss) $ 757,747 $ 757,747 $ 358,008 $ 358,008 $ (16,151 ) $ (16,151 ) Net earnings attributable to noncontrolling interests (130,786 ) (130,786 ) (53,084 ) (53,084 ) (25,129 ) (25,129 ) Impact from public subsidiaries' dilutive securities (a)(b) — (25,228 ) — (33,531 ) — — Net earnings (loss) attributable to IAC shareholders $ 626,961 $ 601,733 $ 304,924 $ 271,393 $ (41,280 ) $ (41,280 ) Denominator: Weighted average basic shares outstanding 83,407 83,407 80,089 80,089 80,045 80,045 Dilutive securities (a) (b) (c) (d) (e) (f) (g) — 7,915 — 5,221 — — Denominator for earnings per share—weighted average shares (a) (b) (c) (d) (e) (f) (g) 83,407 91,322 80,089 85,310 80,045 80,045 Earnings (loss) per share attributable to IAC shareholders: Earnings (loss) per share $ 7.52 $ 6.59 $ 3.81 $ 3.18 $ (0.52 ) $ (0.52 ) __________________________________________________________________ (a) For the year ended December 31, 2018 , it is more dilutive for IAC to settle certain MTCH equity awards. For the years ended December 31, 2017 and 2016, it is more dilutive for MTCH to settle certain MTCH equity awards. (b) For the years ended December 31, 2018 and 2017, it is more dilutive for IAC to settle certain ANGI equity awards. The impact on earnings of ANGI dilutive securities is not applicable for periods prior to the Combination. (c) If the effect is dilutive, weighted average common shares outstanding include the incremental shares that would be issued upon the assumed exercise of stock options, warrants and subsidiary denominated equity, exchange of the Company's Exchangeable Notes and vesting of restricted stock units ("RSUs"). For the years ended December 31, 2018 and 2017, 3.5 million and 6.9 million potentially dilutive securities, respectively, are excluded from the calculation of diluted earnings per share because their inclusion would have been anti-dilutive. (d) For the year ended December 31, 2016, the Company had a loss from operations; therefore, approximately 11.3 million potentially dilutive securities were excluded from computing dilutive earnings per share because the impact would have been anti-dilutive. Accordingly, the weighted average basic shares outstanding were used to compute all earnings per share amounts. (e) Market-based awards and performance-based stock units ("PSUs") are considered contingently issuable shares. Shares issuable upon exercise or vesting of market-based awards and PSUs are included in the denominator for earnings per share if (i) the applicable market or performance condition(s) has been met and (ii) the inclusion of the market-based awards and PSUs is dilutive for the respective reporting periods. For both the years ended December 31, 2018 and 2017, 0.1 million shares underlying market-based awards and PSUs were excluded from the calculation of diluted earnings per share because the market or performance conditions had not been met. (f) It is the Company's intention to settle the Exchangeable Notes through a combination of cash, equal to the face amount of the notes, and shares; therefore, the Exchangeable Notes are only dilutive for periods during which the average price of IAC common stock exceeds the approximate $152.18 per share exchange price per $1,000 principal amount of the Exchangeable Notes. For the year ended December 31, 2018, the average price of IAC common stock exceeded $152.18 and the dilutive impact of the Exchangeable Notes was 0.3 million shares. For the year ended December 31, 2017, the Exchangeable Notes were anti-dilutive. (g) See " Note 11—Stock-based Compensation " for additional information on equity instruments denominated in the shares of certain subsidiaries.

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Changes in Outstanding Stock Options	Stock options outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows: December 31, 2018 Shares Weighted Weighted Aggregate (Shares and intrinsic value in thousands) Options outstanding at January 1, 2018 6,586 $ 60.57 Granted 80 152.53 Exercised (774 ) 52.56 Forfeited (72 ) 57.52 Expired (6 ) 19.51 Options outstanding at December 31, 2018 5,814 $ 62.97 6.1 $ 698,128 Options exercisable 3,592 $ 59.64 5.3 $ 443,293
Schedule of Information for Stock Options Outstanding and Exercisable	The following table summarizes the information about stock options outstanding and exercisable at December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Outstanding at Weighted- Weighted- Exercisable at Weighted- Weighted- (Shares in thousands) $20.01 to $30.00 30 1.1 $ 21.60 30 1.1 $ 21.60 $30.01 to $40.00 389 2.3 32.30 389 2.3 32.30 $40.01 to $50.00 1,541 5.8 43.35 961 5.0 44.26 $50.01 to $60.00 246 3.2 59.85 244 3.2 59.86 $60.01 to $70.00 1,173 6.3 65.27 767 6.0 65.62 $70.01 to $80.00 1,840 7.4 75.33 822 6.8 74.72 $80.01 to $90.00 500 6.3 84.31 375 6.3 84.31 Greater than $90.01 95 9.1 148.30 4 8.9 125.08 5,814 6.1 62.97 3,592 5.3 59.64
Schedule of Weighted Average Assumptions	The following are the weighted average assumptions used in the Black-Scholes option pricing model: Years Ended December 31, 2018 2017 2016 Expected volatility 27 % 29 % 29 % Risk-free interest rate 2.7 % 2.0 % 1.2 % Expected term 6.2 years 5.2 years 4.8 years Dividend yield — % — % — %
Schedule of Outstanding Unvested RSUs and PSUs	Unvested RSUs and PSUs outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows: RSUs PSUs Number Weighted Number Weighted (Shares in thousands) Unvested at January 1, 2018 360 $ 80.81 130 $ 76.00 Granted 153 183.33 30 152.53 Vested (49 ) 78.54 — — Forfeited (5 ) 98.81 (17 ) 76.00 Unvested at December 31, 2018 459 $ 115.12 143 $ 92.02

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	Years Ended December 31, 2018 2017 2016 (In thousands) Revenue: Match Group $ 1,729,850 $ 1,330,661 $ 1,118,110 ANGI Homeservices 1,132,241 736,386 498,890 Vimeo 159,641 103,332 78,805 Dotdash 130,991 90,890 77,913 Applications 582,287 577,998 604,140 Emerging & Other 528,250 468,589 762,609 Inter-segment elimination (368 ) (617 ) (585 ) Total $ 4,262,892 $ 3,307,239 $ 3,139,882 The following table presents the revenue of the Company's segments disaggregated by type of service: Years Ended December 31, 2018 2017 2016 (In thousands) Match Group Direct revenue: North America $ 902,478 $ 741,334 $ 673,944 International 774,693 539,915 393,420 Direct revenue 1,677,171 1,281,249 1,067,364 Indirect revenue (principally advertising revenue) 52,679 49,412 50,746 Total Match Group revenue $ 1,729,850 $ 1,330,661 $ 1,118,110 Supplemental information on Direct revenue Tinder $ 805,316 $ 403,216 $ 168,522 Other brands 871,855 878,033 898,842 Total Direct revenue $ 1,677,171 $ 1,281,249 $ 1,067,364 ANGI Homeservices Marketplace: Consumer connection revenue $ 704,341 $ 521,481 $ 382,466 Membership subscription revenue 66,214 56,135 43,573 Other revenue 3,940 3,798 2,827 Marketplace revenue 774,495 581,414 428,866 Advertising and other revenue 287,676 97,483 32,981 North America 1,062,171 678,897 461,847 Consumer connection revenue 50,913 40,009 28,124 Membership subscription revenue 17,362 16,596 7,936 Advertising and other revenue 1,795 884 983 Europe 70,070 57,489 37,043 Total ANGI Homeservices revenue $ 1,132,241 $ 736,386 $ 498,890 Vimeo Platform revenue $ 146,665 $ 99,650 $ 78,805 Hardware revenue 12,976 3,682 — Years Ended December 31, 2018 2017 2016 (In thousands) Total Vimeo revenue $ 159,641 $ 103,332 $ 78,805 Dotdash Advertising revenue $ 113,014 $ 81,948 $ 76,099 Affiliate commerce commission revenue 14,458 7,372 1,685 Other revenue 3,519 1,570 129 Total Dotdash revenue $ 130,991 $ 90,890 $ 77,913 Applications Desktop Advertising revenue: Google advertising revenue $ 426,964 $ 480,774 $ 523,335 Other 10,992 6,762 10,037 Advertising revenue 437,956 487,536 533,372 Subscription and other revenue 20,815 34,613 29,943 Total Desktop 458,771 522,149 563,315 Mosaic Group Subscription and other revenue 104,975 27,980 21,787 Advertising revenue 18,541 27,869 19,038 Total Mosaic Group 123,516 55,849 40,825 Total Applications revenue $ 582,287 $ 577,998 $ 604,140 Emerging & Other Advertising revenue: Google advertising revenue $ 357,752 $ 225,576 $ 269,192 Other 66,733 53,911 75,008 Advertising revenue 424,485 279,487 344,200 Other revenue 103,765 169,497 160,329 Test preparation revenue — 19,605 86,517 Product revenue — — 171,563 Total Emerging & Other revenue $ 528,250 $ 468,589 $ 762,609
Schedule of Revenue by Geographic Areas	Years Ended December 31, 2018 2017 2016 (In thousands) Revenue United States $ 2,824,928 $ 2,323,050 $ 2,318,976 All other countries 1,437,964 984,189 820,906 Total $ 4,262,892 $ 3,307,239 $ 3,139,882
Schedule of Long-lived Assets by Geographic Areas	December 31, 2018 2017 (In thousands) Long-lived assets (excluding goodwill and intangible assets) United States $ 289,756 $ 286,541 All other countries 29,044 28,629 Total $ 318,800 $ 315,170
Schedule of Reconciliation of Adjusted EBITDA to Operating Income (Loss)	The following tables present operating income (loss) and Adjusted EBITDA by reportable segment: Years Ended December 31, 2018 2017 2016 (In thousands) Operating Income (Loss): Match Group $ 553,294 $ 360,517 $ 315,549 ANGI Homeservices 63,906 (149,176 ) 25,363 Vimeo (35,594 ) (27,328 ) (25,350 ) Dotdash 18,778 (15,694 ) (248,705 ) Applications 94,834 130,176 109,663 Emerging & Other 29,964 17,412 (99,696 ) Corporate (160,043 ) (127,441 ) (109,449 ) Total $ 565,139 $ 188,466 $ (32,625 ) Years Ended December 31, 2018 2017 2016 (In thousands) Adjusted EBITDA: (a) Match Group $ 653,931 $ 468,941 $ 403,380 ANGI Homeservices $ 247,506 $ 37,858 $ 45,851 Vimeo $ (28,045 ) $ (23,607 ) $ (20,281 ) Dotdash $ 21,384 $ (2,763 ) $ (16,846 ) Applications $ 131,837 $ 136,757 $ 132,276 Emerging & Other $ 36,178 $ 25,862 $ 10,111 Corporate $ (74,017 ) $ (67,755 ) $ (53,272 ) _______________________________________________________________________________ (a) The Company's primary financial measure is Adjusted EBITDA, which is defined as operating income excluding: (1) stock-based compensation expense; (2) depreciation; and (3) acquisition-related items consisting of (i) amortization of intangible assets and impairments of goodwill and intangible assets, if applicable, and (ii) gains and losses recognized on changes in the fair value of contingent consideration arrangements. The Company believes this measure is useful for analysts and investors as this measure allows a more meaningful comparison between our performance and that of our competitors. Moreover, our management uses this measure internally to evaluate the performance of our businesses, and this measure is one of the primary metrics on which our internal budgets are based and by which management is compensated. The above items are excluded from our Adjusted EBITDA measure because these items are non-cash in nature. Adjusted EBITDA has certain limitations in that it does not take into account the impact to IAC's statement of operations of certain expenses. The following tables reconcile operating income (loss) for the Company's reportable segments and net earnings attributable to IAC shareholders to Adjusted EBITDA: Year Ended December 31, 2018 Operating Stock-Based Depreciation Amortization Acquisition-related Contingent Consideration Fair Value Adjustments Adjusted EBITDA (In thousands) Match Group $ 553,294 $ 66,031 $ 32,968 $ 1,318 $ 320 $ 653,931 ANGI Homeservices 63,906 $ 97,078 $ 24,310 $ 62,212 $ — $ 247,506 Vimeo (35,594 ) $ — $ 1,200 $ 6,349 $ — $ (28,045 ) Dotdash 18,778 $ — $ 969 $ 1,637 $ — $ 21,384 Applications 94,834 $ — $ 2,601 $ 33,266 $ 1,136 $ 131,837 Emerging & Other 29,964 $ 919 $ 1,678 $ 3,617 $ — $ 36,178 Corporate (160,043 ) $ 74,392 $ 11,634 $ — $ — $ (74,017 ) Total 565,139 Interest expense (109,327 ) Other income, net 305,746 Earnings before income taxes 761,558 Income tax provision (3,811 ) Net earnings 757,747 Net earnings attributable to noncontrolling interests (130,786 ) Net earnings attributable to IAC shareholders $ 626,961 Year Ended December 31, 2017 Operating Income (Loss) Stock-Based Compensation Expense Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Adjusted EBITDA (In thousands) Match Group $ 360,517 $ 69,090 $ 32,613 $ 1,468 $ 5,253 $ 468,941 ANGI Homeservices (149,176 ) $ 149,230 $ 14,543 $ 23,261 $ — $ 37,858 Vimeo (27,328 ) $ — $ 1,408 $ 2,313 $ — $ (23,607 ) Dotdash (15,694 ) $ — $ 2,255 $ 10,676 $ — $ (2,763 ) Applications 130,176 $ — $ 3,863 $ 2,170 548 — $ 136,757 Emerging & Other 17,412 $ 2,130 $ 4,065 $ 2,255 $ — $ 25,862 Corporate (127,441 ) $ 44,168 $ 15,518 $ — $ — $ (67,755 ) Total 188,466 Interest expense (105,295 ) Other expense, net (16,213 ) Earnings before income taxes 66,958 Income tax benefit 291,050 Net earnings 358,008 Net earnings attributable to noncontrolling interests (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 Year Ended December 31, 2016 Operating Income (Loss) Stock-Based Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Goodwill Impairment Adjusted EBITDA (In thousands) Match Group $ 315,549 $ 52,370 $ 27,726 $ 16,932 $ (9,197 ) $ — $ 403,380 ANGI Homeservices 25,363 $ 8,916 $ 8,419 $ 3,153 $ — $ — $ 45,851 Vimeo (25,350 ) $ — $ 1,085 $ 4,176 $ (192 ) $ — $ (20,281 ) Dotdash (248,705 ) $ — $ 2,775 $ 30,754 $ — $ 198,330 $ (16,846 ) Applications 109,663 $ — $ 5,095 $ 5,483 $ 12,035 $ — $ 132,276 Emerging & Other (99,696 ) $ 1,258 $ 12,675 $ 18,928 $ (91 ) $ 77,037 $ 10,111 Corporate (109,449 ) $ 42,276 $ 13,901 $ — $ — $ — $ (53,272 ) Total (32,625 ) Interest expense (109,110 ) Other income, net 60,650 Loss before income taxes (81,085 ) Income tax benefit 64,934 Net loss (16,151 ) Net earnings attributable to noncontrolling interests (25,129 ) Net loss attributable to IAC shareholders $ (41,280 )
Schedule of Reconciliation of Segment Assets to Total Assets	The following tables reconcile segment assets to total assets by reportable segment: December 31, 2018 Segment Assets (b) Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 377,965 $ 58,351 $ 1,245,013 $ 230,684 $ 6,956 $ 1,918,969 ANGI Homeservices 497,327 70,859 892,800 171,486 132,809 1,765,281 Vimeo 33,568 1,014 77,152 — 9,442 121,176 Dotdash 39,276 3,229 — 13,500 1,514 57,519 Applications 153,781 4,867 504,892 39,463 22,447 725,450 Emerging & Other 95,858 1,638 7,002 2,971 150 107,619 Corporate (c) 1,934,943 178,842 — — — 2,113,785 Total $ 3,132,718 $ 318,800 $ 2,726,859 $ 458,104 $ 173,318 6,809,799 Add: Deferred tax assets (d) 64,786 Total Assets $ 6,874,585 December 31, 2017 Segment Assets (b) Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 467,338 $ 61,620 $ 1,247,899 $ 228,296 $ 2,049 $ 2,007,202 ANGI Homeservices 264,450 53,292 768,317 153,447 175,124 1,414,630 Vimeo 30,507 1,972 77,303 — 15,655 125,437 Dotdash 27,190 4,077 — 6,000 3,152 40,419 Applications 345,532 7,004 447,242 60,600 847 861,225 Emerging & Other 255,107 2,377 18,305 10,800 7,767 294,356 Corporate (c) 873,392 184,828 — — — 1,058,220 Total $ 2,263,516 $ 315,170 $ 2,559,066 $ 459,143 $ 204,594 5,801,489 Add: Deferred tax assets (d) 66,321 Total Assets $ 5,867,810 _____________________________________ (b) Consistent with the Company's primary metric (described in (a) above), the Company excludes, if applicable, property and equipment, goodwill and intangible assets from the measure of segment assets presented above. (c) Corporate assets consist primarily of cash and cash equivalents, marketable securities and IAC's headquarters building. (d) Total segment assets differ from total assets on a consolidated basis as a result of unallocated deferred tax assets.
Schedule of Capital Expenditures by Segment	The following table presents capital expenditures by reportable segment: Years Ended December 31, 2018 2017 2016 (In thousands) Capital expenditures: Match Group $ 30,954 $ 28,833 $ 46,098 ANGI Homeservices 46,976 26,837 16,660 Vimeo 209 109 1,959 Dotdash 102 825 1,671 Applications 111 227 1,196 Emerging & Other 1,119 852 6,683 Corporate 6,163 17,840 3,772 Total $ 85,634 $ 75,523 $ 78,039

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments under Operating Lease Agreements	Future minimum payments under operating lease agreements are as follows: Years Ending December 31, (In thousands) 2019 $ 38,770 2020 46,440 2021 40,998 2022 34,066 2023 30,567 Thereafter 255,563 Total $ 446,404
Schedule of Commercial Commitments Outstanding	The Company also has funding commitments that could potentially require its performance in the event of demands by third parties or contingent events as follows: Amount of Commitment Expiration Per Period Less Than 1 Year 1-3 Years 3-5 Years More Than 5 Years Total Amounts Committed (In thousands) Purchase obligations $ 40,428 $ 23,897 $ — $ — $ 64,325 Letters of credit and surety bonds 449 — — 2,272 2,721 Total commercial commitments $ 40,877 $ 23,897 $ — $ 2,272 $ 67,046

SUPPLEMENTAL CASH FLOW INFORM_2

SUPPLEMENTAL CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Schedule of Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information: Years Ended December 31, 2018 2017 2016 (In thousands) Cash paid (received) during the year for: Interest $ 90,485 $ 92,461 $ 107,360 Income tax payments 45,154 35,598 69,103 Income tax refunds (33,698 ) (42,025 ) (23,877 )

CONSOLIDATED FINANCIAL STATEM_2

CONSOLIDATED FINANCIAL STATEMENT DETAILS (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Current Assets	December 31, 2018 2017 (In thousands) Other current assets: Capitalized costs to obtain a contract with a customer $ 69,817 $ — Prepaid expenses 55,586 49,350 Capitalized downloadable search toolbar costs, net 33,365 31,588 Income taxes receivable 10,132 33,239 Production costs 2,260 18,570 Other 57,093 52,627 Other current assets $ 228,253 $ 185,374
Schedule of Property and Equipment, Net	Asset Category Estimated Useful Lives Buildings and leasehold improvements 3 to 39 Years Computer equipment and capitalized software 2 to 3 Years Furniture and other equipment 3 to 12 Years December 31, 2018 2017 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 249,026 $ 246,038 Computer equipment and capitalized software 229,083 218,529 Furniture and other equipment 86,694 88,930 Projects in progress 29,204 19,094 Land 11,591 14,390 Property and equipment 605,598 586,981 Accumulated depreciation and amortization (286,798 ) (271,811 ) Property and equipment, net of accumulated depreciation and amortization $ 318,800 $ 315,170
Schedule of Accrued Expenses and Other Current Liabilities	December 31, 2018 2017 (In thousands) Accrued expenses and other current liabilities: Accrued employee compensation and benefits $ 137,583 $ 108,431 Accrued advertising expense 105,520 96,445 Other 191,783 162,048 Accrued expenses and other current liabilities $ 434,886 $ 366,924
Schedule of Revenue	Years Ended December 31, 2018 2017 2016 (In thousands) Revenue: Service revenue $ 4,249,227 $ 3,302,937 $ 2,967,474 Product revenue 13,665 4,302 172,408 Revenue $ 4,262,892 $ 3,307,239 $ 3,139,882
Schedule of Cost of Revenue	Years Ended December 31, 2018 2017 2016 (In thousands) Cost of revenue: Cost of service revenue $ 898,736 $ 647,226 $ 617,058 Cost of product revenue 12,410 3,782 138,672 Cost of revenue $ 911,146 $ 651,008 $ 755,730
Schedule of Other (Expense) Income, Net	Years Ended December 31, 2018 2017 2016 (In thousands) Other income (expense), net $ 305,746 $ (16,213 ) $ 60,650

TRANSACTION AND INTEGRATION R_2

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Purchase Price	The table below summarizes the purchase price: Angie's List (In thousands) Class A common stock $ 763,684 Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock 1,913 Fair value of vested and pro rata portion of unvested stock options attributable to pre-combination services 11,749 Fair value of the pro rata portion of unvested restricted stock units attributable to pre-combination services 4,038 Total purchase price $ 781,384 A summary of the costs incurred, payments made and the related accrual is presented below. Years Ended December 31, 2018 2017 (In thousands) Transaction and integration related costs $ 3,584 $ 44,101 Stock-based compensation expense 70,645 122,066 Total $ 74,229 $ 166,167 December 31, 2018 2017 (In thousands) Accrual as of January 1 $ 8,480 $ — Costs incurred 3,584 44,101 Payments made (12,064 ) (35,621 ) Accrual as of December 31 $ — $ 8,480 The costs are allocated as follows in the accompanying consolidated statement of operations: Year Ended December 31, 2018 Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense — 2,161 2,161 General and administrative expense 3,584 61,010 64,594 Product development expense — 7,474 7,474 Total $ 3,584 $ 70,645 $ 74,229 Year Ended December 31, 2017 Transaction and Integration Related Costs Stock-based Compensation Expense Total (In thousands) Cost of revenue $ — $ — $ — Selling and marketing expense 7,430 24,416 31,846 General and administrative expense 36,120 83,420 119,540 Product development expense 551 14,230 14,781 Total $ 44,101 $ 122,066 $ 166,167

GUARANTOR AND NON-GUARANTOR F_2

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Guarantor and Nonguarantor Financial Statements [Abstract]
Schedule of Condensed Balance Sheet	Balance sheet at December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 1,018,082 $ — $ 1,113,550 $ — $ 2,131,632 Marketable securities 98,299 — 25,366 — 123,665 Accounts receivable, net of allowance and reserves — 99,970 179,219 — 279,189 Other current assets 27,349 29,222 171,682 — 228,253 Intercompany receivables — 1,423,456 — (1,423,456 ) — Property and equipment, net of accumulated depreciation and amortization 6,526 163,281 148,993 — 318,800 Goodwill — 412,009 2,314,850 — 2,726,859 Intangible assets, net of accumulated amortization — 43,914 587,508 — 631,422 Investment in subsidiaries 1,897,699 214,519 — (2,112,218 ) — Other non-current assets 274,789 94,290 251,315 (185,629 ) 434,765 Total assets $ 3,322,744 $ 2,480,661 $ 4,792,483 $ (3,721,303 ) $ 6,874,585 Current portion of long-term debt $ — $ — $ 13,750 $ — $ 13,750 Accounts payable, trade 1,304 36,293 37,310 — 74,907 Other current liabilities 41,721 95,405 657,775 — 794,901 Long-term debt, net 34,262 — 2,211,286 — 2,245,548 Income taxes payable 15 1,707 35,862 — 37,584 Intercompany liabilities 402,056 — 1,021,400 (1,423,456 ) — Other long-term liabilities 261 18,181 257,594 (185,629 ) 90,407 Redeemable noncontrolling interests — — 65,687 — 65,687 Shareholders' equity (deficit) 2,843,125 2,329,075 (216,857 ) (2,112,218 ) 2,843,125 Noncontrolling interests — — 708,676 — 708,676 Total liabilities and shareholders' equity $ 3,322,744 $ 2,480,661 $ 4,792,483 $ (3,721,303 ) $ 6,874,585 Balance sheet at December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 585,639 $ — $ 1,045,170 $ — $ 1,630,809 Marketable securities 4,995 — — — 4,995 Accounts receivable, net of allowance and reserves 31 109,289 194,707 — 304,027 Other current assets 49,159 33,387 102,828 — 185,374 Intercompany receivables — 668,703 — (668,703 ) — Property and equipment, net of accumulated depreciation and amortization 2,811 174,323 138,036 — 315,170 Goodwill — 412,010 2,147,056 — 2,559,066 Intangible assets, net of accumulated amortization — 74,852 588,885 — 663,737 Investment in subsidiaries 2,077,898 554,998 — (2,632,896 ) — Other non-current assets 170,073 87,306 79,688 (132,435 ) 204,632 Total assets $ 2,890,606 $ 2,114,868 $ 4,296,370 $ (3,434,034 ) $ 5,867,810 Current portion of long-term debt $ — $ — $ 13,750 $ — $ 13,750 Accounts payable, trade 5,163 30,469 40,939 — 76,571 Other current liabilities 29,489 88,050 591,868 — 709,407 Long-term debt, net 34,572 — 1,944,897 — 1,979,469 Income taxes payable 16 1,605 24,003 — 25,624 Intercompany liabilities 390,827 — 277,876 (668,703 ) — Other long-term liabilities 511 18,613 186,610 (132,435 ) 73,299 Redeemable noncontrolling interests — — 42,867 — 42,867 Shareholders' equity 2,430,028 1,976,131 656,765 (2,632,896 ) 2,430,028 Noncontrolling interests — — 516,795 — 516,795 Total liabilities and shareholders' equity $ 2,890,606 $ 2,114,868 $ 4,296,370 $ (3,434,034 ) $ 5,867,810
Schedule of Condensed Statement of Operations	Statement of operations for the year ended December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 850,475 $ 3,412,795 $ (378 ) $ 4,262,892 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 195 262,912 648,330 (291 ) 911,146 Selling and marketing expense 977 313,769 1,204,844 (150 ) 1,519,440 General and administrative expense 141,727 49,563 582,720 69 774,079 Product development expense 2,003 56,431 250,901 (6 ) 309,329 Depreciation 1,203 12,497 61,660 — 75,360 Amortization of intangibles — 29,437 78,962 — 108,399 Total operating costs and expenses 146,105 724,609 2,827,417 (378 ) 3,697,753 Operating (loss) income (146,105 ) 125,866 585,378 — 565,139 Equity in earnings of unconsolidated affiliates 731,834 20,083 — (751,917 ) — Interest expense (1,700 ) — (107,627 ) — (109,327 ) Other (expense) income, net (a) (18,834 ) 503,261 199,757 (378,438 ) 305,746 Earnings before income taxes 565,195 649,210 677,508 (1,130,355 ) 761,558 Income tax benefit (provision) 61,766 (56,612 ) (8,965 ) — (3,811 ) Net earnings 626,961 592,598 668,543 (1,130,355 ) 757,747 Net earnings attributable to noncontrolling interests — — (130,786 ) — (130,786 ) Net earnings attributable to IAC shareholders $ 626,961 $ 592,598 $ 537,757 $ (1,130,355 ) $ 626,961 Comprehensive income attributable to IAC shareholders $ 601,683 $ 601,232 $ 515,766 $ (1,116,998 ) $ 601,683 ____________________ (a) During the year ended December 31, 2018, foreign cash of $396.2 million was repatriated to the U.S, of which $25.2 million was between non-guarantor subsidiaries. Statement of operations for the year ended December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 753,858 $ 2,553,998 $ (617 ) $ 3,307,239 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 160 159,488 491,865 (505 ) 651,008 Selling and marketing expense 1,250 353,186 1,027,304 (519 ) 1,381,221 General and administrative expense 100,237 62,340 556,273 407 719,257 Product development expense 2,421 55,232 193,226 — 250,879 Depreciation 1,564 20,668 52,033 — 74,265 Amortization of intangibles — 11,213 30,930 — 42,143 Total operating costs and expenses 105,632 662,127 2,351,631 (617 ) 3,118,773 Operating (loss) income (105,632 ) 91,731 202,367 — 188,466 Equity in earnings of unconsolidated affiliates 419,149 20,755 — (439,904 ) — Interest expense (20,339 ) — (84,956 ) — (105,295 ) Other (expense) income, net (30,787 ) 28,434 (13,860 ) — (16,213 ) Earnings before income taxes 262,391 140,920 103,551 (439,904 ) 66,958 Income tax benefit (provision) 42,533 (119,957 ) 368,474 — 291,050 Net earnings 304,924 20,963 472,025 (439,904 ) 358,008 Net earnings attributable to noncontrolling interests — — (53,084 ) — (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 $ 20,963 $ 418,941 $ (439,904 ) $ 304,924 Comprehensive income attributable to IAC shareholders $ 367,370 $ 7,629 $ 498,032 $ (505,661 ) $ 367,370 Statement of operations for the year ended December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 960,000 $ 2,180,487 $ (605 ) $ 3,139,882 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 859 297,712 457,571 (412 ) 755,730 Selling and marketing expense 2,353 417,051 828,016 (323 ) 1,247,097 General and administrative expense 89,583 83,636 357,097 130 530,446 Product development expense 4,807 69,778 138,180 — 212,765 Depreciation 1,610 26,514 43,552 — 71,676 Amortization of intangibles — 41,157 38,269 — 79,426 Goodwill impairment — 253,245 22,122 — 275,367 Total operating costs and expenses 99,212 1,189,093 1,884,807 (605 ) 3,172,507 Operating (loss) income (99,212 ) (229,093 ) 295,680 — (32,625 ) Equity in earnings of unconsolidated affiliates 49,545 6,774 — (56,319 ) — Interest expense (26,876 ) — (82,234 ) — (109,110 ) Other (expense) income, net (1,879 ) 10,209 52,320 — 60,650 (Loss) earnings before income taxes (78,422 ) (212,110 ) 265,766 (56,319 ) (81,085 ) Income tax benefit (provision) 37,142 77,851 (50,059 ) — 64,934 Net (loss) earnings (41,280 ) (134,259 ) 215,707 (56,319 ) (16,151 ) Net earnings attributable to noncontrolling interests — — (25,129 ) — (25,129 ) Net (loss) earnings attributable to IAC shareholders $ (41,280 ) $ (134,259 ) $ 190,578 $ (56,319 ) $ (41,280 ) Comprehensive (loss) income attributable to IAC shareholders $ (76,431 ) $ (142,494 ) $ 145,039 $ (2,545 ) $ (76,431 )
Schedule of Condensed Statement of Cash Flows	Statement of cash flows for the year ended December 31, 2018: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (38,737 ) $ 583,498 $ 822,227 $ (378,860 ) $ 988,128 Cash flows from investing activities: Acquisitions, net of cash acquired (4,142 ) (50,530 ) (9,824 ) — (64,496 ) Capital expenditures (5,274 ) (1,396 ) (78,964 ) — (85,634 ) Proceeds from maturities and sales of marketable debt securities 298,600 — 35,000 — 333,600 Purchases of marketable debt securities (390,005 ) — (59,671 ) — (449,676 ) Net proceeds from the sale of businesses and investments 408 87,254 49,057 — 136,719 Purchases of investments (39,180 ) — (13,800 ) — (52,980 ) Other, net (5,000 ) 7,451 6,576 — 9,027 Net cash (used in) provided by investing activities (144,593 ) 42,779 (71,626 ) — (173,440 ) Cash flows from financing activities: Repurchases of IAC debt (363 ) — — — (363 ) Proceeds from issuance of Match Group debt — — 260,000 — 260,000 Principal payments on ANGI Homeservices Term Loan — — (13,750 ) — (13,750 ) Debt issuance costs — — (5,449 ) — (5,449 ) Purchase of IAC treasury stock (82,891 ) — — — (82,891 ) Purchase of Match Group treasury stock — — (133,455 ) — (133,455 ) Proceeds from the exercise of IAC stock options 41,700 — — — 41,700 Proceeds from the exercise of Match Group and ANGI Homeservices stock options — — 4,705 — 4,705 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (18,982 ) — — — (18,982 ) Withholding taxes paid on behalf of Match Group and ANGI Homeservices employees on net settled stock-based awards — — (237,564 ) — (237,564 ) Dividends paid to Match Group noncontrolling interests — — (105,126 ) — (105,126 ) Purchase of noncontrolling interests — — (16,063 ) — (16,063 ) Acquisition-related contingent consideration payments — — (185 ) — (185 ) Intercompany 673,308 (625,338 ) (426,830 ) 378,860 — Other, net 2,674 (939 ) (7,110 ) — (5,375 ) Net cash provided by (used in) financing activities 615,446 (626,277 ) (680,827 ) 378,860 (312,798 ) Total cash provided 432,116 — 69,774 — 501,890 Effect of exchange rate changes on cash, cash equivalents, and restricted cash 327 — (2,214 ) — (1,887 ) Net increase in cash, cash equivalents, and restricted cash 432,443 — 67,560 — 500,003 Cash, cash equivalents, and restricted cash at beginning of period 585,639 — 1,048,043 — 1,633,682 Cash, cash equivalents, and restricted cash at end of period $ 1,018,082 $ — $ 1,115,603 $ — $ 2,133,685 Statement of cash flows for the year ended December 31, 2017: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (52,582 ) $ 131,700 $ 337,581 $ 416,699 Cash flows from investing activities: Acquisitions, net of cash acquired — (2,550 ) (144,003 ) (146,553 ) Capital expenditures (337 ) (1,169 ) (74,017 ) (75,523 ) Proceeds from maturities and sales of marketable debt securities 114,350 — — 114,350 Purchases of marketable debt securities (29,891 ) — — (29,891 ) Net proceeds from the sale of businesses and investments 1,266 — 184,512 185,778 Purchases of investments — — (9,106 ) (9,106 ) Other, net — 1,944 1,050 2,994 Net cash provided by (used in) investing activities 85,388 (1,775 ) (41,564 ) 42,049 Cash flows from financing activities: Proceeds from issuance of IAC debt — — 517,500 517,500 Repurchases of IAC debt (393,464 ) — — (393,464 ) Proceeds from issuance of Match Group debt — — 525,000 525,000 Principal payments on Match Group debt — — (445,172 ) (445,172 ) Borrowing under ANGI Homeservices Term Loan — — 275,000 275,000 Purchase of exchangeable note hedge — — (74,365 ) (74,365 ) Proceeds from issuance of warrants 23,650 — — 23,650 Debt issuance costs — — (33,744 ) (33,744 ) Purchase of IAC treasury stock (56,424 ) — — (56,424 ) Proceeds from the exercise of IAC stock options 82,397 — — 82,397 Proceeds from the exercise of Match Group and ANGI Homeservices stock options — — 61,095 61,095 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (93,832 ) — — (93,832 ) Withholding taxes paid on behalf of Match Group and ANGI Homeservices employees on net settled stock-based awards — — (264,323 ) (264,323 ) Purchase of Match Group stock-based awards — — (272,459 ) (272,459 ) Purchase of noncontrolling interests — — (15,439 ) (15,439 ) Acquisition-related contingent consideration payments — — (27,289 ) (27,289 ) Intercompany 416,396 (129,925 ) (286,471 ) — Other, net 251 — (5,251 ) (5,000 ) Net cash used in financing activities (21,026 ) (129,925 ) (45,918 ) (196,869 ) Total cash provided 11,780 — 250,099 261,879 Effect of exchange rate changes on cash, cash equivalents, and restricted cash 75 — 11,529 11,604 Net increase in cash, cash equivalents, and restricted cash 11,855 — 261,628 273,483 Cash, cash equivalents, and restricted cash at beginning of period 573,784 — 786,415 1,360,199 Cash, cash equivalents, and restricted cash at end of period $ 585,639 $ — $ 1,048,043 $ 1,633,682 Statement of cash flows for the year ended December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (62,686 ) $ 128,503 $ 278,421 $ — $ 344,238 Cash flows from investing activities: Acquisitions, net of cash acquired — — (18,403 ) — (18,403 ) Capital expenditures (479 ) (5,792 ) (71,768 ) — (78,039 ) Proceeds from maturities and sales of marketable debt securities 252,369 — — — 252,369 Purchases of marketable debt securities (313,943 ) — — — (313,943 ) Investments in time deposits — — (87,500 ) — (87,500 ) Proceeds from maturities of time deposits — — 87,500 — 87,500 Net proceeds from the sale of businesses and investments 73,843 1,779 96,606 — 172,228 Purchases of investments — — (12,565 ) — (12,565 ) Intercompany (155,104 ) — — 155,104 — Other, net 126 910 10,179 — 11,215 Net cash (used in) provided by investing activities (143,188 ) (3,103 ) 4,049 155,104 12,862 Cash flows from financing activities: Repurchases of IAC debt (126,409 ) — — — (126,409 ) Proceeds from issuance of Match Group debt — — 400,000 — 400,000 Principal payments on Match Group debt — — (450,000 ) — (450,000 ) Debt issuance costs — — (7,811 ) — (7,811 ) Purchase of IAC treasury stock (308,948 ) — — — (308,948 ) Proceeds from the exercise of IAC stock options 25,821 — — — 25,821 Proceeds from the exercise of Match Group stock options — — 39,378 — 39,378 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (26,716 ) — — — (26,716 ) Withholding taxes paid on behalf of Match Group employees on net settled stock-based awards — — (29,830 ) — (29,830 ) Purchase of noncontrolling interests (1,400 ) — (1,340 ) — (2,740 ) Acquisition-related contingent consideration payments — (351 ) (1,829 ) — (2,180 ) Intercompany 122,965 (122,965 ) 155,104 (155,104 ) — Other, net (313 ) (2,084 ) (308 ) — (2,705 ) Net cash (used in) provided by financing activities (315,000 ) (125,400 ) 103,364 (155,104 ) (492,140 ) Total cash (used) provided (520,874 ) — 385,834 — (135,040 ) Effect of exchange rate changes on cash, cash equivalents, and restricted cash — — (6,434 ) — (6,434 ) Net (decrease) increase in cash, cash equivalents, and restricted cash (520,874 ) — 379,400 — (141,474 ) Cash, cash equivalents, and restricted cash at beginning of period 1,094,658 — 407,015 — 1,501,673 Cash, cash equivalents, and restricted cash at end of period $ 573,784 $ — $ 786,415 $ — $ 1,360,199

QUARTERLY RESULTS (UNAUDITED) (

QUARTERLY RESULTS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Results	Quarter Ended March 31 (a) Quarter Ended June 30 (b) Quarter Ended September 30 (c) Quarter Ended December 31 (d) (In thousands, except per share data) Year Ended December 31, 2018 Revenue $ 995,075 $ 1,059,122 $ 1,104,592 $ 1,104,103 Cost of revenue 201,962 218,224 237,238 253,722 Operating income 89,950 168,437 172,832 133,920 Net earnings 87,839 280,854 171,577 217,477 Net earnings attributable to IAC shareholders 71,082 218,353 145,774 191,752 Per share information attributable to IAC shareholders: Basic earnings per share (g) $ 0.86 $ 2.61 $ 1.75 $ 2.29 Diluted earnings per share (g) $ 0.71 $ 2.32 $ 1.49 $ 2.04 Quarter Ended March 31 Quarter Ended June 30 Quarter Ended September 30 (e) Quarter Ended December 31 (f) (In thousands, except per share data) Year Ended December 31, 2017 Revenue $ 760,833 $ 767,387 $ 828,434 $ 950,585 Cost of revenue 145,958 139,033 166,290 199,727 Operating income (loss) 37,060 75,635 (18,589 ) 94,360 Net earnings 28,463 80,557 225,639 23,349 Net earnings attributable to IAC shareholders 26,209 66,268 179,643 32,804 Per share information attributable to IAC shareholders: Basic earnings per share (g) $ 0.34 $ 0.84 $ 2.22 $ 0.40 Diluted earnings per share (g) $ 0.29 $ 0.70 $ 1.79 $ 0.37 _______________________________________________________________________________ (a) The first quarter of 2018 includes after-tax stock-based compensation expense of $14.6 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination, as well as after-tax costs of $4.1 million related to the Combination (including $2.8 million of deferred revenue write-offs). (b) The second quarter of 2018 includes: i. after-tax stock-based compensation expense of $12.8 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination, and the acceleration of certain converted equity awards resulting from the termination of Angie's List employees in connection with the Combination, as well as after-tax costs of $2.0 million related to the Combination (including $1.8 million of deferred revenue write-offs). ii. after-tax realized and unrealized gains of $133.3 million related to the sale of a certain equity investment. (c) The third quarter of 2018 includes after-tax stock-based compensation expense of $12.3 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination. (d) The fourth quarter of 2018 includes: i. after-tax stock-based compensation expense of $14.4 million related to the modification of previously issued HomeAdvisor equity awards and previously issued Angie's List equity awards, both of which were converted into ANGI Homeservices' equity awards in the Combination. ii. combined after-tax gains of $92.5 million related to the sales of Dictionary.com, Electus, Felix and CityGrid. iii. after-tax impairment charges related to indefinite-lived intangible assets of $21.3 million . (e) The third quarter of 2017 includes: i. after-tax stock-based compensation expense of $60.9 million related to the modification of previously issued HomeAdvisor vested awards, which were converted into ANGI Homeservices equity awards, and the acceleration of certain Angie’s List equity awards in connection with the Combination, as well as after-tax costs of $17.4 million related to the Combination. ii. a reduction to the income tax provision of $257.0 million related to excess tax benefits generated by the exercise, purchase and settlement of stock-based awards. (f) The fourth quarter of 2017 includes after-tax stock-based compensation expense of $15.8 million related to the modification of previously issued HomeAdvisor unvested awards, which were converted into ANGI Homeservices equity awards, the expense related to previously issued Angie's List equity awards and the acceleration of certain Angie's List equity awards resulting from the termination of employees in connection with the Combination, as well as after-tax costs of $13.9 million related to the Combination (including $7.6 million of deferred revenue write-offs). (g) Quarterly per share amounts may not add to the related annual per share amount because of differences in the average common shares outstanding during each period.

ORGANIZATION - NARRATIVE (Detai

ORGANIZATION - NARRATIVE (Details)	Dec. 31, 2018
Match Group
Noncontrolling Interest [Line Items]
Ownership interest (as a percent)	81.10%
Voting interest (as a percent)	97.60%
ANGI Homeservices
Noncontrolling Interest [Line Items]
Ownership interest (as a percent)	83.90%
Voting interest (as a percent)	98.10%

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	Jan. 01, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2018USD ($)arrangement	Dec. 31, 2017USD ($)arrangement	Dec. 31, 2016USD ($)arrangement	Jan. 01, 2019USD ($)	Oct. 01, 2018USD ($)
Intangible Assets and Goodwill
Amortization of capitalized contract costs											$ 355,300,000
Current capitalized contract costs		$ 69,817,000				$ 0					69,817,000	$ 0
Non-current capitalized contract costs		4,500,000									$ 4,500,000
Period of payment due from customers for accounts receivable											30 days
Deferred revenue	$ 332,200,000
Deferred revenue recognized during period											$ 330,200,000
Current deferred revenue		360,015,000				342,483,000					360,015,000	342,483,000
Non-current deferred revenue		1,700,000									$ 1,700,000
Maturity period at purchase (less than)											91 days
Revenue		1,104,103,000	$ 1,104,592,000	$ 1,059,122,000	$ 995,075,000	950,585,000	$ 828,434,000	$ 767,387,000	$ 760,833,000		$ 4,262,892,000	3,307,239,000	$ 3,139,882,000
Accounts receivable, net of allowance and reserves		279,189,000				304,027,000					$ 279,189,000	304,027,000
Impairment charges on indefinite-lived intangible assets		27,700,000
Estimated weighted-average useful life (in years)											18 months
Property and equipment, net of accumulated depreciation and amortization		$ 318,800,000				315,170,000					$ 318,800,000	315,170,000
Excess of goodwill fair value over carrying value (less than) (as a percent)		110.00%									110.00%
Goodwill		$ 265,100,000									$ 265,100,000
Excess of indefinite-lived intangible asset fair value over carrying value (less than) (as a percent)		110.00%									110.00%
Indefinite-lived intangible assets		$ 131,300,000									$ 131,300,000
Advertising expense											1,200,000,000	1,100,000,000	1,000,000,000
Amounts reclassified to earnings											$ 52,000	$ 3,360,000	$ (6,937,000)
Put and call arrangements exercised | arrangement											2	2	1
Retained earnings		1,258,794,000				595,038,000					$ 1,258,794,000	$ 595,038,000
Deferred income taxes		23,600,000				35,070,000					23,600,000	35,070,000
Increase (decrease) in deferred revenue											49,468,000	39,154,000	$ 35,803,000
Cumulative effect of adoption of new accounting pronouncement	40,205,000
Unrealized gains, net, on equity securities held											124,170,000
Accounting Standards Update 2014-09
Intangible Assets and Goodwill
Retained earnings	40,200,000					3,400,000						3,400,000
Accounting Standards Update 2016-01
Intangible Assets and Goodwill
Cumulative effect of adoption of new accounting pronouncement	0
Unrealized gains, net, on equity securities held				$ 126,400,000
Accounting Standards Update 2016-02 | Forecast
Intangible Assets and Goodwill
Right-of-use asset														$ 160,000,000
Lease liability														$ 160,000,000
Foreign Currency Translation Adjustment
Intangible Assets and Goodwill
Amounts reclassified to earnings											52,000	(673,000)	(9,850,000)
Foreign Currency Translation Adjustment | Other (Expense) Income, Net
Intangible Assets and Goodwill
Amounts reclassified to earnings											(100,000)	700,000	9,900,000
Redeemable Noncontrolling Interest
Intangible Assets and Goodwill
Purchase of noncontrolling interests											4,100,000	6,300,000	7,900,000
Trade Names
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets													$ 9,000,000
Software and software development costs
Intangible Assets and Goodwill
Property and equipment, net of accumulated depreciation and amortization		58,100,000				46,400,000					58,100,000	46,400,000
Google Inc.
Intangible Assets and Goodwill
Accounts receivable, net of allowance and reserves		69,100,000				$ 72,400,000					$ 69,100,000	$ 72,400,000
Google Inc. | Revenue | Customer Concentration Risk
Intangible Assets and Goodwill
Concentration risk (as a percent)											19.00%	22.00%	26.00%
Google Inc. | Revenue | Customer Concentration Risk | Operating Segments
Intangible Assets and Goodwill
Concentration risk (as a percent)											94.00%	96.00%	96.00%
Desktop | Trade Names
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets											$ 27,700,000
College Humor Media | Trade Names
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets											$ 1,100,000
Ask Media Group
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets		$ 77,000,000
Minimum | Discount Rate
Intangible Assets and Goodwill
Measurement input (as a percent)		0.125				0.125					0.125	0.125
Minimum | Discount Rate | Indefinite-lived Intangible Assets
Intangible Assets and Goodwill
Measurement input (as a percent)		0.105				0.11					0.105	0.11
Minimum | Royalty Rate | Trade Names
Intangible Assets and Goodwill
Measurement input (as a percent)		0.02									0.02
Minimum | Royalty Rate | Indefinite-lived Intangible Assets
Intangible Assets and Goodwill
Measurement input (as a percent)		0.0075				0.02					0.0075	0.02
Maximum | Discount Rate
Intangible Assets and Goodwill
Measurement input (as a percent)		0.15				0.175					0.15	0.175
Maximum | Discount Rate | Indefinite-lived Intangible Assets
Intangible Assets and Goodwill
Measurement input (as a percent)		0.35				0.16					0.35	0.16
Maximum | Royalty Rate | Trade Names
Intangible Assets and Goodwill
Measurement input (as a percent)		0.06									0.06
Maximum | Royalty Rate | Indefinite-lived Intangible Assets
Intangible Assets and Goodwill
Measurement input (as a percent)		0.080				0.07					0.080	0.07
Match Group
Intangible Assets and Goodwill
Market capitalization															$ 15,700,000,000
Amount by which market capitalization exceeds carrying value															15,100,000,000
Match Group | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 1,729,850,000	$ 1,330,661,000	$ 1,118,110,000
Property and equipment, net of accumulated depreciation and amortization		$ 58,351,000				$ 61,620,000					$ 58,351,000	61,620,000
Match Group | Minimum
Intangible Assets and Goodwill
Period of membership subscription											1 month
Match Group | Maximum
Intangible Assets and Goodwill
Period of membership subscription											6 months
ANGI Homeservices
Intangible Assets and Goodwill
Period of membership subscription											1 year
Market capitalization															10,700,000,000
Amount by which market capitalization exceeds carrying value															$ 9,600,000,000
ANGI Homeservices | Accounting Standards Update 2014-09
Intangible Assets and Goodwill
Current capitalized contract costs	29,700,000
Non-current capitalized contract costs	4,200,000
Retained earnings	25,900,000
Deferred income taxes	8,000,000
ANGI Homeservices | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 1,132,241,000	736,386,000	498,890,000
Property and equipment, net of accumulated depreciation and amortization		70,859,000				53,292,000					$ 70,859,000	53,292,000
ANGI Homeservices | Angie's List
Intangible Assets and Goodwill
Period of membership subscription											1 year
Vimeo | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 159,641,000	103,332,000	78,805,000
Property and equipment, net of accumulated depreciation and amortization		1,014,000				1,972,000					$ 1,014,000	1,972,000
Vimeo | Minimum
Intangible Assets and Goodwill
Period of membership subscription											1 month
Vimeo | Maximum
Intangible Assets and Goodwill
Period of membership subscription											1 year
Publishing and Applications | Google Inc.
Intangible Assets and Goodwill
Revenue											$ 825,200,000	740,700,000	824,400,000
Applications | Accounting Standards Update 2014-09
Intangible Assets and Goodwill
Retained earnings	15,500,000
Deferred income taxes	4,900,000
Increase (decrease) in deferred revenue	$ (20,300,000)
Applications | Operating Segments
Intangible Assets and Goodwill
Revenue											582,287,000	577,998,000	$ 604,140,000
Property and equipment, net of accumulated depreciation and amortization		4,867,000				7,004,000					$ 4,867,000	$ 7,004,000
Applications | Google Inc. | Revenue | Customer Concentration Risk | Operating Segments
Intangible Assets and Goodwill
Concentration risk (as a percent)											73.00%	83.00%	87.00%
Applications | Mosaic Group | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 123,516,000	$ 55,849,000	$ 40,825,000
Applications | Minimum | Desktop
Intangible Assets and Goodwill
Period of membership subscription											1 year
Applications | Minimum | Mosaic Group
Intangible Assets and Goodwill
Period of membership subscription											1 year
Applications | Maximum | Desktop
Intangible Assets and Goodwill
Period of membership subscription											2 years
Applications | Maximum | Mosaic Group
Intangible Assets and Goodwill
Period of membership subscription											2 years
Publishing
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets										$ 275,400,000
Emerging & Other | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 528,250,000	468,589,000	$ 762,609,000
Property and equipment, net of accumulated depreciation and amortization		1,638,000				2,377,000					$ 1,638,000	$ 2,377,000
Emerging & Other | Google Inc. | Revenue | Customer Concentration Risk | Operating Segments
Intangible Assets and Goodwill
Concentration risk (as a percent)											68.00%	48.00%	35.00%
Dotdash
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets		198,300,000
Dotdash | Trade Names
Intangible Assets and Goodwill
Impairment charges on indefinite-lived intangible assets													$ 2,600,000
Dotdash | Operating Segments
Intangible Assets and Goodwill
Revenue											$ 130,991,000	$ 90,890,000	$ 77,913,000
Property and equipment, net of accumulated depreciation and amortization		$ 3,229,000				$ 4,077,000					$ 3,229,000	$ 4,077,000

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Buildings and leasehold improvements | Minimum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	3 years
Buildings and leasehold improvements | Maximum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	39 years
Computer equipment and capitalized software | Minimum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	2 years
Computer equipment and capitalized software | Maximum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	3 years
Furniture and other equipment | Minimum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	3 years
Furniture and other equipment | Maximum
Property and equipment, net of accumulated depreciation and amortization:
Estimated useful lives, minimum (in years)	12 years

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Effect of Adoption of ASU 2014-09 (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenues	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Operating costs and expenses									3,697,753	3,118,773	3,172,507
Operating income (loss)	133,920	172,832	168,437	89,950	94,360	(18,589)	75,635	37,060	565,139	188,466	(32,625)
Net earnings	$ 217,477	$ 171,577	$ 280,854	$ 87,839	$ 23,349	$ 225,639	$ 80,557	$ 28,463	757,747	358,008	(16,151)
Operating segments | Match Group
Disaggregation of Revenue [Line Items]
Revenues									1,729,850	1,330,661	1,118,110
Operating costs and expenses									1,176,556
Operating income (loss)									553,294	360,517	315,549
Operating segments | ANGI Homeservices
Disaggregation of Revenue [Line Items]
Revenues									1,132,241	736,386	498,890
Operating costs and expenses									1,068,335
Operating income (loss)									63,906	(149,176)	25,363
Operating segments | Vimeo
Disaggregation of Revenue [Line Items]
Revenues									159,641	103,332	78,805
Operating costs and expenses									195,235
Operating income (loss)									(35,594)	(27,328)	(25,350)
Operating segments | Dotdash
Disaggregation of Revenue [Line Items]
Revenues									130,991	90,890	77,913
Operating costs and expenses									112,213
Operating income (loss)									18,778	(15,694)	(248,705)
Operating segments | Applications
Disaggregation of Revenue [Line Items]
Revenues									582,287	577,998	604,140
Operating costs and expenses									487,453
Operating income (loss)									94,834	130,176	109,663
Operating segments | Emerging & Other
Disaggregation of Revenue [Line Items]
Revenues									528,250	468,589	762,609
Operating costs and expenses									498,286
Operating income (loss)									29,964	17,412	(99,696)
Inter-segment eliminations
Disaggregation of Revenue [Line Items]
Revenues									(368)	(617)	(585)
Corporate
Disaggregation of Revenue [Line Items]
Operating costs and expenses									159,675
Operating income (loss)									(160,043)	$ (127,441)	$ (109,449)
Under ASC 605
Disaggregation of Revenue [Line Items]
Revenues									4,263,387
Operating costs and expenses									3,700,861
Operating income (loss)									562,526
Net earnings									755,741
Under ASC 605 | Operating segments | Match Group
Disaggregation of Revenue [Line Items]
Revenues									1,729,850
Operating costs and expenses									1,176,556
Operating income (loss)									553,294
Under ASC 605 | Operating segments | ANGI Homeservices
Disaggregation of Revenue [Line Items]
Revenues									1,132,241
Operating costs and expenses									1,073,275
Operating income (loss)									58,966
Under ASC 605 | Operating segments | Vimeo
Disaggregation of Revenue [Line Items]
Revenues									160,931
Operating costs and expenses									196,212
Operating income (loss)									(35,281)
Under ASC 605 | Operating segments | Dotdash
Disaggregation of Revenue [Line Items]
Revenues									130,991
Operating costs and expenses									112,213
Operating income (loss)									18,778
Under ASC 605 | Operating segments | Applications
Disaggregation of Revenue [Line Items]
Revenues									581,492
Operating costs and expenses									484,644
Operating income (loss)									96,848
Under ASC 605 | Operating segments | Emerging & Other
Disaggregation of Revenue [Line Items]
Revenues									528,250
Operating costs and expenses									498,286
Operating income (loss)									29,964
Under ASC 605 | Inter-segment eliminations
Disaggregation of Revenue [Line Items]
Revenues									(368)
Under ASC 605 | Corporate
Disaggregation of Revenue [Line Items]
Operating costs and expenses									159,675
Operating income (loss)									(160,043)
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09
Disaggregation of Revenue [Line Items]
Revenues									(495)
Operating costs and expenses									(3,108)
Operating income (loss)									2,613
Net earnings									2,006
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | Match Group
Disaggregation of Revenue [Line Items]
Revenues									0
Operating costs and expenses									0
Operating income (loss)									0
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | ANGI Homeservices
Disaggregation of Revenue [Line Items]
Revenues									0
Operating costs and expenses									(4,940)
Operating income (loss)									4,940
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | Vimeo
Disaggregation of Revenue [Line Items]
Revenues									(1,290)
Operating costs and expenses									(977)
Operating income (loss)									(313)
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | Dotdash
Disaggregation of Revenue [Line Items]
Revenues									0
Operating costs and expenses									0
Operating income (loss)									0
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | Applications
Disaggregation of Revenue [Line Items]
Revenues									795
Operating costs and expenses									2,809
Operating income (loss)									(2,014)
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Operating segments | Emerging & Other
Disaggregation of Revenue [Line Items]
Revenues									0
Operating costs and expenses									0
Operating income (loss)									0
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Inter-segment eliminations
Disaggregation of Revenue [Line Items]
Revenues									0
Accounting Standards Update 2014-09 | Effect of adoption of ASU No. 2014-09 | Corporate
Disaggregation of Revenue [Line Items]
Operating costs and expenses									0
Operating income (loss)									$ 0

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 2,131,632	$ 1,630,809	$ 1,329,187	$ 1,481,447
Restricted cash included in other current assets	1,633	2,873	20,464	126
Restricted cash included in other assets	420	0	10,548	20,100
Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows	$ 2,133,685	$ 1,633,682	$ 1,360,199	$ 1,501,673

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforwards
Excess tax benefit attributable to stock-based compensation		$ 143.3	$ 361.8
Excess tax benefit attributable to stock-based compensation that reduces income taxes payable		142.2
Excess tax benefit attributable to stock-based compensation that increases deferred tax asset		1.1
Excess tax benefits from stock-based awards				$ 51.8
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Income tax benefit related to net operating loss carryforwards		9.5
Tax credit carryforwards		105.4
Tax credit carryforwards that can be carried forward indefinitely		24.2
Tax credit carryforwards expiring primarily by 2018 and 2037		81.2
Valuation Allowance
Decrease in valuation allowance		16.7
Valuation allowance at end of period		115.9
Income Taxes Paid, Net [Abstract]
Interest on income taxes accrued		3.4	3
Income tax penalties accrued		1.4	1.7
Unrecognized tax benefits including tax interest accrued		52.3	39.7
Tax positions for which the ultimate deductibility is highly certain but timing is uncertain		49.1	37.2
Change in unrecognized tax benefits unrelated to Federal income taxes statute of limitations expiring within twelve months of current reporting period		21.6
Tax benefits that would impact effective tax rate		21.6
Reduction in the Transition Tax	$ 9.2
Tax on earnings of foreign subsidiaries		1
Earnings of foreign subsidiaries		103.1
Federal Tax Authority
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Net operating loss carryforwards		856
Net operating loss carryforwards not subject to expiration		13.9
Net operating loss carryforwards without restrictions		569.9
State Tax Authority
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Net operating loss carryforwards		698.7
Net operating loss carryforwards without restrictions		350.4
Tax credit carryforwards		3.9
Foreign Tax Authority
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Net operating loss carryforwards		383.4
Net operating loss carryforwards not subject to expiration		352
Net operating loss carryforwards subject to expiration within 20 years		31.4
Tax credit carryforwards		53.2
Tax credit carryforwards related to research and development		48.3
Continuing Operations
Income Taxes Paid, Net [Abstract]
Unrecognized tax (benefit) expense net of related deferred taxes		0.3	(0.1)	0.4
Deferred taxes for interest on unrecognized tax benefits (continuing operations)		$ 0.1	$ 0.1	$ 0.2

INCOME TAXES - Income before In

INCOME TAXES - Income before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S.	$ 630,417	$ (52,606)	$ (248,433)
Foreign	131,141	119,564	167,348
Earnings (loss) before income taxes	$ 761,558	$ 66,958	$ (81,085)

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax provision (benefit):
Federal		$ (2,849)	$ (31,844)	$ 23,343
State		2,569	1,964	3,662
Foreign		38,770	24,108	27,242
Current income tax provision (benefit)		38,490	(5,772)	54,247
Deferred income tax provision (benefit):
Federal		(21,792)	(255,477)	(100,798)
State		172	(28,364)	(9,518)
Foreign		(13,059)	(1,437)	(8,865)
Deferred income tax benefit		(34,679)	(285,278)	(119,181)
Income tax provision (benefit)	$ 257,000	$ 3,811	$ (291,050)	$ (64,934)

INCOME TAXES - Income Taxes (Pa

INCOME TAXES - Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other current assets	$ 10,132	$ 33,239
Income taxes payable	(37,584)	(25,624)
Net income taxes payable	(28,796)	(2,234)
Other non-current assets	64,786	66,321
Deferred income taxes	(23,600)	(35,070)
Net deferred tax assets	41,186	31,251
Other current assets
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other current assets	10,132	33,239
Other non-current assets
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other non-current assets	11,401	1,949
Other non-current assets	64,786	66,321
Accrued expenses and other current liabilities
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Accrued expenses and other current liabilities	(12,745)	(11,798)
Income taxes payable
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Income taxes payable	(37,584)	(25,624)
Deferred income taxes
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Deferred income taxes	$ (23,600)	$ (35,070)

INCOME TAXES - Deferred Tax Ass

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Accrued expenses	$ 23,525	$ 22,234
NOL carryforwards	291,639	292,812
Tax credit carryforwards	89,397	78,715
Stock-based compensation	82,698	77,976
Other	30,106	42,331
Total deferred tax assets	517,365	514,068
Less valuation allowance	(115,853)	(132,598)
Net deferred tax assets	401,512	381,470
Deferred tax liabilities:
Investment in subsidiaries	(238,650)	(247,167)
Intangibles	(77,669)	(87,811)
Fair value investment	(22,927)
Other	(21,080)	(15,241)
Total deferred tax liabilities	(360,326)	(350,219)
Net deferred tax assets	$ 41,186	$ 31,251

INCOME TAXES - Effective Income

INCOME TAXES - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at the federal statutory rate of 21% (35% for 2017 and 2016)		$ 159,927	$ 23,435	$ (28,446)
State income taxes, net of effect of federal tax benefit		14,887	86	(3,880)
Deferred tax adjustment for enacted changes in tax laws and rates		(129,654)	(358,901)	3,998
Realization of certain deferred tax assets		(13,200)	(3,133)	0
Transition tax		(9,190)	62,667	0
Deferred tax adjustment for enacted changes in tax laws and rates		(7,488)	705	(4,594)
Research credit		(4,023)	(5,304)	(2,231)
Foreign income taxed at a different statutory tax rate		(3,206)	(14,725)	(27,115)
Non-taxable sale and non-deductible goodwill associated with ShoeBuy		0	0	(13,142)
Goodwill impairment of Dotdash and Emerging & Other		0	0	10,649
Non-deductible impairments for certain cost method investments			2,669	3,489
Other, net		(4,242)	1,451	(3,662)
Income tax provision (benefit)	$ 257,000	$ 3,811	$ (291,050)	$ (64,934)

INCOME TAXES - Income Tax Conti

INCOME TAXES - Income Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Balance at beginning of the period	$ 36,732	$ 38,372	$ 40,808
Additions based on tax positions related to the current year	10,334	2,050	2,033
Additions for tax positions of prior years	4,716	1,994	2,676
Reductions for tax positions of prior years	(400)	(3,761)	(743)
Settlements	0	0	(5,107)
Expiration of applicable statutes of limitations	(2,507)	(1,923)	(1,295)
Balance at end of the period	$ 48,875	$ 36,732	$ 38,372

BUSINESS COMBINATION - Narrativ

BUSINESS COMBINATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Sep. 29, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Angie's List
Business Acquisition [Line Items]
Proportion of voting interests acquired (as a percent)	100.00%
Total purchase price	$ 781,384
Basis of purchase price (shares)	61.3
Share price (USD per share)	$ 12.46
Cash acquisition price	$ 1,900
Cash per share paid to acquiree shareholders' who elected payout (USD per share)	$ 8.50
Revenue		$ 58,900
Net earnings (loss)		(21,800)
One-Time Acquisition-related Costs
Business Acquisition [Line Items]
Severance costs		28,700
Severance and retention costs		19,800
Write-off due to deferred revenue		$ 7,800
Adjustment to decrease in transaction related costs			$ 34,100
Modification of Equity Awards
Business Acquisition [Line Items]
Adjustment to increase (decrease) in share-based compensation			77,100	$ (81,400)
Amortization Adjustment
Business Acquisition [Line Items]
Adjustment to decrease in amortization of intangible assets			$ (31,900)	(56,100)
Deferred Revenue Write Off Adjustment
Business Acquisition [Line Items]
Adjustment to decrease in revenues				$ (34,100)

BUSINESS COMBINATION - Purchase

BUSINESS COMBINATION - Purchase Price (Details) - Angie's List $ in Thousands	Sep. 29, 2017USD ($)
Business Acquisition [Line Items]
Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock	$ 1,900
Total purchase price	781,384
Common Stock
Business Acquisition [Line Items]
Consideration transferred, equity interests	763,684
Cash consideration for holders who elected to receive $8.50 in cash per share of Angie's List common stock	1,913
Common Stock | Fair value of vested and pro rata portion of unvested stock options attributable to pre-combination services
Business Acquisition [Line Items]
Consideration transferred, equity interests	11,749
Common Stock | Fair value of the pro rata portion of unvested restricted stock units attributable to pre-combination services
Business Acquisition [Line Items]
Consideration transferred, equity interests	$ 4,038

BUSINESS COMBINATION - Prelimin

BUSINESS COMBINATION - Preliminary Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Sep. 29, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 2,726,859	$ 2,559,066		$ 1,924,052
Angie's List
Business Acquisition [Line Items]
Cash and cash equivalents			$ 44,270
Other current assets			11,280
Property and equipment			16,341
Goodwill			543,674
Intangible assets			317,300
Total assets			932,865
Deferred revenue			(32,595)
Other current liabilities			(46,150)
Long-term debt—related party			(61,498)
Deferred income taxes			(9,833)
Other long-term liabilities			(1,405)
Net assets acquired			$ 781,384

BUSINESS COMBINATION - Prelim_2

BUSINESS COMBINATION - Preliminary Estimated Fair Value of Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2018
Acquired Intangible Assets [Line Items]
Weighted-Average Useful Life (Years)		18 months
Angie's List
Acquired Intangible Assets [Line Items]
Total identifiable intangible assets acquired	$ 317,300
Angie's List | Service providers
Acquired Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 90,500
Weighted-Average Useful Life (Years)	3 years
Angie's List | Developed technology
Acquired Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 63,900
Weighted-Average Useful Life (Years)	6 years
Angie's List | Memberships
Acquired Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 15,900
Weighted-Average Useful Life (Years)	3 years
Angie's List | User base
Acquired Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 10,000
Weighted-Average Useful Life (Years)	1 year
Angie's List | Indefinite-lived trade names and trademarks
Acquired Intangible Assets [Line Items]
Indefinite-lived trade name and trademarks	$ 137,000

BUSINESS COMBINATION - Pro-Form

BUSINESS COMBINATION - Pro-Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition, Pro Forma Information [Abstract]
Revenue	$ 3,529,600	$ 3,429,105
Net earnings (loss) attributable to ANGI Homeservices Inc. shareholders	$ 364,496	$ (143,133)
Basic earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders (USD per share)	$ 4.55	$ (1.79)
Diluted earnings (loss) per share attributable to ANGI Homeservices Inc. shareholders (USD per share)	$ 4.27	$ (1.79)

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 2,726,859	$ 2,559,066	$ 1,924,052
Intangible assets with indefinite lives	458,104	459,143
Intangible assets with definite lives, net of accumulated amortization	173,318	204,594
Total goodwill and intangible assets, net	$ 3,358,281	$ 3,222,803

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Goodwill by Reporting Unit (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)operating_segmentreportingunit	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Goodwill
Balance at beginning of period	$ 2,559,066	$ 2,559,066	$ 1,924,052
Additions		208,423	661,396
(Deductions)		(22,188)	(74,430)
Foreign Exchange Translation		(18,442)	48,048
Balance at end of period		2,726,859	2,559,066
Match Group
Goodwill
Balance at beginning of period	1,247,899	1,247,899	1,206,538
Additions		11,187	255
(Deductions)		0	0
Foreign Exchange Translation		(14,073)	41,106
Balance at end of period		1,245,013	1,247,899
ANGI Homeservices
Goodwill
Balance at beginning of period	768,317	768,317	170,611
Additions		142,768	590,772
(Deductions)		(14,373)	0
Transfers In/(Out)		0
Foreign Exchange Translation		(3,912)	6,934
Balance at end of period		892,800	768,317
Vimeo
Goodwill
Balance at beginning of period	77,303	77,303	9,649
Additions		0	67,654
(Deductions)		(151)	0
Transfers In/(Out)		0
Foreign Exchange Translation		0	0
Balance at end of period		77,152	77,303
Applications
Goodwill
Balance at beginning of period	447,242	447,242	447,242
Additions		50,784	0
(Deductions)		0	0
Transfers In/(Out)		7,323
Foreign Exchange Translation		(457)	0
Balance at end of period		504,892	447,242
Accumulated goodwill impairment loss		529,100
Applications | Desktop
Goodwill
Balance at beginning of period	265,146	265,146	265,146
Additions		0	0
(Deductions)		0	0
Transfers In/(Out)		0
Foreign Exchange Translation		0	0
Balance at end of period		265,146	265,146
Applications | Mosaic Group
Goodwill
Balance at beginning of period	182,096	182,096	182,096
Additions		50,784	0
(Deductions)		0	0
Transfers In/(Out)		7,323
Foreign Exchange Translation		(457)	0
Balance at end of period		239,746	182,096
Emerging & Other
Goodwill
Balance at beginning of period	$ 18,305	18,305	90,012
Additions		3,684	2,715
(Deductions)		(7,664)	(74,430)
Transfers In/(Out)		(7,323)
Foreign Exchange Translation			8
Balance at end of period		7,002	$ 18,305
Emerging & Other | Ask Media Group
Goodwill
Accumulated goodwill impairment loss		399,700
Emerging & Other | College Humor Media
Goodwill
Accumulated goodwill impairment loss		11,600
Dotdash
Goodwill
Accumulated goodwill impairment loss		$ 198,300
Publishing
Goodwill
Number of operating segments | operating_segment	1
Number of reporting units | reportingunit	1

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Intangible Assets with Definite Lives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Intangible assets with definite lives
Gross Carrying Amount	$ 309,723	$ 279,551
Accumulated Amortization	(136,405)	(74,957)
Total	$ 173,318	$ 204,594
Weighted-Average Useful Life (Years)	3 years 9 months 18 days	3 years 8 months 12 days
Technology
Intangible assets with definite lives
Gross Carrying Amount	$ 143,303	$ 115,200
Accumulated Amortization	(53,199)	(37,357)
Total	$ 90,104	$ 77,843
Weighted-Average Useful Life (Years)	4 years 8 months 12 days	4 years 9 months 18 days
Service professional and contractor relationships
Intangible assets with definite lives
Gross Carrying Amount	$ 99,528	$ 99,497
Accumulated Amortization	(44,674)	(11,452)
Total	$ 54,854	$ 88,045
Weighted-Average Useful Life (Years)	2 years 10 months 24 days	3 years
Customer lists and user base
Intangible assets with definite lives
Gross Carrying Amount	$ 30,099	$ 23,468
Accumulated Amortization	(15,126)	(5,401)
Total	$ 14,973	$ 18,067
Weighted-Average Useful Life (Years)	2 years 10 months 24 days	2 years 2 months 12 days
Memberships
Intangible assets with definite lives
Gross Carrying Amount	$ 15,900	$ 15,900
Accumulated Amortization	(6,640)	(1,340)
Total	$ 9,260	$ 14,560
Weighted-Average Useful Life (Years)	3 years	3 years
Trade names
Intangible assets with definite lives
Gross Carrying Amount	$ 12,393	$ 16,986
Accumulated Amortization	(9,393)	(13,634)
Total	$ 3,000	$ 3,352
Weighted-Average Useful Life (Years)	3 years 3 months 18 days	2 years 7 months 6 days
Other
Intangible assets with definite lives
Gross Carrying Amount	$ 8,500	$ 8,500
Accumulated Amortization	(7,373)	(5,773)
Total	$ 1,127	$ 2,727
Weighted-Average Useful Life (Years)	4 years 9 months 18 days	4 years 9 months 18 days

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Expected Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 71,155
2,020	51,916
2,021	19,433
2,022	16,310
2,023	10,239
Thereafter	4,265
Total	$ 173,318	$ 204,594

FINANCIAL INSTRUMENTS - Narrati

FINANCIAL INSTRUMENTS - Narrative (Details)	Oct. 23, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Mar. 31, 2019USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contractual maturity of current available-for-sale debt securities		1 year
Available-for-sale marketable debt securities in a continuous unrealized loss position for longer than twelve months		$ 0
Gross realized losses from available-for-sale marketable debt securities		0	$ 0	$ 0
Other-than-temporary impairment charges on equity method investments		600,000	2,700,000
Other-than-temporary impairment charges on cost-method investments			9,500,000	$ 10,000,000
Proceeds from sale of cost-method investment	$ 60,200,000
Gain (loss) from sale of cost-method investment	$ 9,100,000
Maximum contingent payment		45,000,000
Gross fair value of contingent consideration arrangement		44,000,000
Current portion of contingent consideration arrangement liability		2,000,000	600,000
Non-current portion of contingent consideration arrangement liability		$ 26,600,000	$ 2,000,000
Subsequent Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maximum contingent payment					$ 2,000,000
Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (as a percent)		0.125	0.125
Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (as a percent)		0.15	0.175
Discount Rate | Contingent Consideration Arrangements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (as a percent)		0.12
Discount Rate | Contingent Consideration Arrangements | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (as a percent)		0.12
Discount Rate | Contingent Consideration Arrangements | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (as a percent)		0.25

FINANCIAL INSTRUMENTS - Fair Va

FINANCIAL INSTRUMENTS - Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Available-for-sale marketable debt securities	$ 123,246	$ 4,995
Marketable equity security	419	0
Total marketable securities	$ 123,665	$ 4,995

FINANCIAL INSTRUMENTS - Current

FINANCIAL INSTRUMENTS - Current Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 123,246	$ 4,995
Gross Unrealized Gains	3	0
Gross Unrealized Losses	(3)	0
Fair Value	123,246	4,995
Treasury discount notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	112,291
Gross Unrealized Gains	3
Gross Unrealized Losses	(3)
Fair Value	112,291
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,955	4,995
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 10,955	$ 4,995

FINANCIAL INSTRUMENTS - Proceed

FINANCIAL INSTRUMENTS - Proceeds from Maturities and Sales of Current Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Proceeds from maturities and sales of available-for-sale marketable debt securities	$ 333,600	$ 114,350	$ 279,485
Gross realized gains	$ 0	$ 0	$ 3,556

FINANCIAL INSTRUMENTS - Long-Te

FINANCIAL INSTRUMENTS - Long-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Equity securities without readily determinable fair values	$ 235,055	$ 0
Equity method investments	0	1,559
Cost method investments	0	63,418
Total long-term investments	$ 235,055	$ 64,977

FINANCIAL INSTRUMENTS - Realize

FINANCIAL INSTRUMENTS - Realized and Unrealized Gains and Losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Adjustments to Carrying Value of Equity Securities without Readily Determinable Fair Value [Abstract]
Upward adjustments (gross unrealized gains)	$ 128,986
Downward adjustments including impairments (gross unrealized losses)	(4,931)
Total	124,055
Adjustments to Carrying Value of Non-Marketable Equity Securities [Abstract]
Realized gains, net, for equity securities sold	27,874
Unrealized gains, net, on equity securities held	124,170
Total gains recognized, net, in other income (expense), net	$ 152,044

FINANCIAL INSTRUMENTS - Financi

FINANCIAL INSTRUMENTS - Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 123,246	$ 4,995
Marketable equity security	419	0
Total	1,818,666	1,167,397
Contingent consideration arrangements	(28,631)	(2,647)
Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	881,234	780,425
Contingent consideration arrangements	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	937,432	386,972
Contingent consideration arrangements	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Contingent consideration arrangements	(28,631)	(2,647)
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	880,815	780,425
Money market funds | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	880,815	780,425
Money market funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Treasury discount notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	561,733	100,457
Marketable securities	112,291
Treasury discount notes | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities	0
Treasury discount notes | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	561,733	100,457
Marketable securities	112,291
Treasury discount notes | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	162,417	215,325
Marketable securities	10,955	4,995
Commercial paper | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities	0	0
Commercial paper | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	162,417	215,325
Marketable securities	10,955	4,995
Commercial paper | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities	0	0
Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	90,036	60,000
Time deposits | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Time deposits | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	90,036	60,000
Time deposits | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		6,195
Certificates of deposit | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Certificates of deposit | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		6,195
Certificates of deposit | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		$ 0
Marketable equity security
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity security	419
Marketable equity security | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity security	419
Marketable equity security | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity security	0
Marketable equity security | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity security	$ 0

FINANCIAL INSTRUMENTS - Unobser

FINANCIAL INSTRUMENTS - Unobservable Inputs of Fair Value Measurements (Details) - Contingent Consideration Arrangements - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Contingent Consideration Arrangement [Roll Forward]
Balance at January 1	$ (2,647)	$ (33,871)
Fair value adjustments	(1,456)	(5,801)
Included in other comprehensive income (loss)	45	(1,404)
Fair value at date of acquisition	(25,521)	0
Settlements	948	38,429
Balance at December 31	$ (28,631)	$ (2,647)

FINANCIAL INSTRUMENTS - Carryin

FINANCIAL INSTRUMENTS - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current portion of long-term debt	$ (13,750)	$ (13,750)
Long-term debt, net	(2,245,548)	(1,979,469)
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current portion of long-term debt	(13,750)	(13,750)
Long-term debt, net	(2,245,548)	(1,979,469)
Unamortized original issue discount and debt issuance costs	(88,900)	(109,100)
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current portion of long-term debt	(12,753)	(13,802)
Long-term debt, net	$ (2,460,204)	$ (2,168,108)

LONG-TERM DEBT - Narrative (Det

LONG-TERM DEBT - Narrative (Details)	Dec. 31, 2018USD ($)$ / sharesshares	Nov. 05, 2018USD ($)	Oct. 02, 2017USD ($)$ / sharesshares	Sep. 30, 2018	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)	Dec. 04, 2017	Nov. 01, 2017USD ($)	Jun. 01, 2016USD ($)
Debt Instrument
Long-term debt	$ 2,348,239,000				$ 2,348,239,000
Exchange price (USD per share) | $ / shares					$ 152.18
Proceeds from issuance of warrants			$ 23,600,000		$ 0	$ 23,650,000	$ 0
Unamortized discount	$ 61,377,000				$ 61,377,000
Purchase of exchangeable note hedge						$ 74,365,000
Senior Notes | 4.875% Senior Notes due November 30, 2018 (the 4.875% Senior Notes); interest payable each May 30 and November 30
Debt Instrument
Stated interest rate (as a percent)	4.75%				4.75%	4.875%	4.875%
Revolving Credit Facility | IAC Credit Facility
Debt Instrument
Maximum borrowing capacity		$ 250,000,000				$ 300,000,000
Credit facility, borrowings outstanding	$ 0				$ 0	$ 0
Commitment fee rate (as a percent)					0.20%	0.25%
Revolving Credit Facility | IAC Credit Facility | Maximum
Debt Instrument
Maximum leverage ratio (not more than)	2.75				3.25
IAC
Debt Instrument
Long-term debt	$ 551,989,000				$ 551,989,000	$ 552,359,000
Unamortized discount	54,025,000				54,025,000	67,158,000
IAC | Senior Notes
Debt Instrument
Long-term debt	$ 463,500,000		$ 517,500,000		$ 463,500,000	$ 450,300,000
Exchangeable shares (shares) | shares			6.5713
Exchange price (USD per share) | $ / shares			$ 152.18		$ 152.18
Period of reported sale price of common stock			20 days	5 days
Period of consecutive reported sale price of common stock			30 days	5 days
Percentage of exchange price on applicable trading day			130.00%
Percentage of product of last reported price			98.00%
Proceeds from issuance of debt			$ 499,500,000
Repayment of net premium on exchangeable note hedge and warrants			50,700,000
Amount of debt discount and increase to additional paid in capital			70,400,000
Transaction costs allocated to liability and equity			18,000,000
Class of warrant outstanding (shares) | shares	3,400,000				3,400,000	3,400,000
Exercise price of warrants (USD per share) | $ / shares	$ 229.70				$ 229.70	$ 229.70
Proceeds from issuance of warrants			23,600,000
Unamortized discount	$ 54,000,000				$ 54,000,000	$ 67,200,000
If-converted value in excess of principal					105,000,000
Purchase of exchangeable note hedge			$ 74,400,000
Debt interest expense					21,200,000	5,200,000
Amortization of debt discount (premium)					13,100,000	3,200,000
Amortization of debt issuance costs					$ 3,500,000	$ 900,000
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1
Debt Instrument
Stated interest rate (as a percent)	0.875%		0.875%		0.875%	0.875%
Long-term debt	$ 517,500,000				$ 517,500,000	$ 517,500,000
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1 | Minimum
Debt Instrument
Stated interest rate (as a percent)	0.875%				0.875%
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1 | Maximum
Debt Instrument
Stated interest rate (as a percent)	3.88%				3.88%
IAC | Senior Notes | 4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Stated interest rate (as a percent)	4.75%				4.75%	4.75%
Long-term debt	$ 34,489,000				$ 34,489,000	$ 34,859,000
Match Group
Debt Instrument
Long-term debt	1,535,000,000				1,535,000,000	1,275,000,000
Proceeds from issuance of IAC debt					260,000,000	525,000,000	$ 400,000,000
Unamortized discount	$ 7,352,000				$ 7,352,000	$ 8,668,000
Match Group | Senior Notes | 6.75% Senior Notes due December 15, 2022 (the Match Group 6.75% Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Stated interest rate (as a percent)						6.75%		6.75%
Long-term debt							445,200,000
Match Group | Senior Notes | 5.00% Senior Notes due December 15, 2027 (the 5.00% MTCH Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Stated interest rate (as a percent)	5.00%				5.00%	5.00%		5.00%
Long-term debt	$ 450,000,000				$ 450,000,000	$ 450,000,000
Match Group | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1
Debt Instrument
Stated interest rate (as a percent)	6.375%				6.375%	6.375%				6.375%
Long-term debt	$ 400,000,000				$ 400,000,000	$ 400,000,000
Face amount of debt instrument										$ 400,000,000
Match Group | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1 | Maximum
Debt Instrument
Maximum leverage ratio (not more than)						5
Match Group | Term Loan | MTCH Term Loan due November 16, 2022
Debt Instrument
Long-term debt	$ 425,000,000				$ 425,000,000	$ 425,000,000
Match Group | Term Loan | Match Group Term Loan due November 16, 2022
Debt Instrument
Repayment of debt							$ 440,000,000
Effective interest rate (as a percent)	5.09%				5.09%	3.85%
Match Group | Term Loan | Match Group Term Loan due November 16, 2022 | LIBOR
Debt Instrument
Basis spread on variable rate (as a percent)					2.50%
Match Group | Revolving Credit Facility | MTCH Term Loan due November 16, 2022 | Maximum
Debt Instrument
Net leverage ratio affecting ability to pay dividends, make distributions, or repurchase stock					4
Match Group | Revolving Credit Facility | Match Group Credit Agreement
Debt Instrument
Effective interest rate (as a percent)	4.00%				4.00%
Maximum borrowing capacity	$ 500,000,000				$ 500,000,000
Credit facility, borrowings outstanding	260,000,000				$ 260,000,000	$ 0
Commitment fee rate (as a percent)					0.25%	0.30%
Match Group | Revolving Credit Facility | Match Group Credit Agreement | Minimum
Debt Instrument
Minimum interest coverage ratio (not less than)					2
Match Group | Revolving Credit Facility | Match Group Credit Agreement | Maximum
Debt Instrument
Maximum leverage ratio (not more than)					5
Net leverage ratio affecting ability to pay dividends, make distributions, or repurchase stock					2
Match Group | Revolving Credit Facility | Match Group Credit Agreement | LIBOR
Debt Instrument
Basis spread on variable rate (as a percent)					1.50%
ANGI Homeservices | Term Loan
Debt Instrument
Face amount of debt instrument									$ 275,000,000
ANGI Homeservices | Term Loan | Quarterly Payments for First Three Years
Debt Instrument
Stated interest rate (as a percent)									1.25%
ANGI Homeservices | Term Loan | Quarterly Payments in Fourth Year
Debt Instrument
Stated interest rate (as a percent)									2.50%
ANGI Homeservices | Term Loan | Quarterly Payments in Fifth Year
Debt Instrument
Stated interest rate (as a percent)									3.75%
ANGI Homeservices | Term Loan | ANGI Term Loan due November 5, 2023
Debt Instrument
Long-term debt	261,250,000				$ 261,250,000	$ 275,000,000
Basis spread on variable rate (as a percent)					4.00%	3.38%
ANGI Homeservices | Term Loan | ANGI Term Loan due November 5, 2023 | Minimum
Debt Instrument
Minimum interest coverage ratio (not less than)					2
ANGI Homeservices | Term Loan | ANGI Term Loan due November 5, 2023 | Maximum
Debt Instrument
Maximum leverage ratio (not more than)					4.5
Net leverage ratio affecting ability to pay dividends, make distributions, or repurchase stock					4.25
ANGI Homeservices | Term Loan | ANGI Term Loan due November 5, 2023 | LIBOR
Debt Instrument
Basis spread on variable rate (as a percent)					1.50%	2.00%
ANGI Homeservices | Revolving Credit Facility | ANGI Homeservices Credit Facility
Debt Instrument
Maximum borrowing capacity		$ 250,000,000
Credit facility, borrowings outstanding	$ 0				$ 0
Term of debt instrument		5 years
Commitment fee rate (as a percent)					0.25%

LONG-TERM DEBT - Summary (Detai

LONG-TERM DEBT - Summary (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 04, 2017	Oct. 02, 2017	Jun. 01, 2016
Debt Instrument
Total long-term debt	$ 2,348,239,000
Less: unamortized original issue discount	61,377,000
Less: unamortized debt issuance costs	27,564,000
Less: Current portion of long-term debt	13,750,000	$ 13,750,000
Long-term debt, net	2,245,548,000	1,979,469,000
IAC
Debt Instrument
Total long-term debt	551,989,000	552,359,000
Less: unamortized original issue discount	54,025,000	67,158,000
Less: unamortized debt issuance costs	13,298,000	16,740,000
Long-term debt, net	484,666,000	468,461,000
IAC | Senior Notes
Debt Instrument
Total long-term debt	463,500,000	450,300,000		$ 517,500,000
Less: unamortized original issue discount	54,000,000	67,200,000
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1
Debt Instrument
Total long-term debt	$ 517,500,000	$ 517,500,000
Stated interest rate (as a percent)	0.875%	0.875%		0.875%
IAC | Senior Notes | 4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Total long-term debt	$ 34,489,000	$ 34,859,000
Stated interest rate (as a percent)	4.75%	4.75%
Match Group
Debt Instrument
Total long-term debt	$ 1,535,000,000	$ 1,275,000,000
Less: unamortized original issue discount	7,352,000	8,668,000
Less: unamortized debt issuance costs	11,737,000	13,636,000
Long-term debt, net	1,515,911,000	1,252,696,000
Match Group | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1
Debt Instrument
Total long-term debt	$ 400,000,000	$ 400,000,000
Stated interest rate (as a percent)	6.375%	6.375%			6.375%
Match Group | Senior Notes | 5.00% Senior Notes due December 15, 2027 (the 5.00% MTCH Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Total long-term debt	$ 450,000,000	$ 450,000,000
Stated interest rate (as a percent)	5.00%	5.00%	5.00%
Match Group | Term Loan | MTCH Term Loan due November 16, 2022
Debt Instrument
Total long-term debt	$ 425,000,000	$ 425,000,000
Match Group | Credit Facility | MTCH Credit Facility due December 7, 2023
Debt Instrument
Total long-term debt	260,000,000	0
ANGI Homeservices
Debt Instrument
Less: unamortized debt issuance costs	2,529,000	2,938,000
Less: Current portion of long-term debt	13,750,000	13,750,000
Long-term debt, net	244,971,000	258,312,000
ANGI Homeservices | Term Loan | ANGI Term Loan due November 5, 2023
Debt Instrument
Total long-term debt	$ 261,250,000	$ 275,000,000

LONG-TERM DEBT - Debt Instrumen

LONG-TERM DEBT - Debt Instrument Redemption (Details) - Senior Notes	12 Months Ended
	Dec. 31, 2018
6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1 | Period One
Debt Instrument
Redemption rate (as a percent)	104.781%
6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1 | Period Two
Debt Instrument
Redemption rate (as a percent)	103.188%
6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1 | Period Three
Debt Instrument
Redemption rate (as a percent)	101.594%
6.375% Senior Notes due June 1, 2024 (the 6.375% MTCH Senior Notes); interest payable each June 1 and December 1 | Period Four
Debt Instrument
Redemption rate (as a percent)	100.00%
5.00% Senior Notes due December 15, 2027 (the Match Group 5.00% Senior Notes); interest payable each June 15 and December 15, which commences on June 15, 2018 | Period One
Debt Instrument
Redemption rate (as a percent)	102.50%
5.00% Senior Notes due December 15, 2027 (the Match Group 5.00% Senior Notes); interest payable each June 15 and December 15, which commences on June 15, 2018 | Period Two
Debt Instrument
Redemption rate (as a percent)	101.667%
5.00% Senior Notes due December 15, 2027 (the Match Group 5.00% Senior Notes); interest payable each June 15 and December 15, which commences on June 15, 2018 | Period Three
Debt Instrument
Redemption rate (as a percent)	100.833%
5.00% Senior Notes due December 15, 2027 (the Match Group 5.00% Senior Notes); interest payable each June 15 and December 15, which commences on June 15, 2018 | Period Four
Debt Instrument
Redemption rate (as a percent)	100.00%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Period One
Debt Instrument
Redemption rate (as a percent)	101.583%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Period Two
Debt Instrument
Redemption rate (as a percent)	100.792%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Period Three
Debt Instrument
Redemption rate (as a percent)	100.00%

LONG-TERM DEBT - Aggregate Cont

LONG-TERM DEBT - Aggregate Contractual Maturities of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2,019	$ 13,750
2,020	13,750
2,021	13,750
2,022	1,004,489
2,023	452,500
2,024	400,000
2,027	450,000
Total long-term debt	2,348,239
Less: Current portion of long-term debt	13,750	$ 13,750
Less: unamortized original issue discount	61,377
Less: unamortized debt issuance costs	27,564
Long-term debt, net	$ 2,245,548	$ 1,979,469

SHAREHOLDERS' EQUITY - Narrativ

SHAREHOLDERS' EQUITY - Narrative (Details) $ / shares in Units, $ in Thousands	Oct. 02, 2017USD ($)	Dec. 31, 2018USD ($)warrantexchangeable_notevote$ / sharesshares	Dec. 31, 2017USD ($)warrantexchangeable_note$ / sharesshares	Dec. 31, 2016USD ($)shares	May 03, 2016shares
Class of Stock
Directors elected (as a percent)		25.00%
Proceeds from issuance of warrants | $	$ 23,600	$ 0	$ 23,650	$ 0
Warrants exercised during period | warrant		0	0
Exchangeable notes exchanged during period | exchangeable_note		0	0
Trade date fair value of shares acquired during period | $		$ 82,891	$ 50,121	$ 315,250
Class B Convertible Common Stock
Class of Stock
Number of votes | vote		10
Common Stock
Class of Stock
Number of votes | vote		1
Common stock reserved (shares)		28,000,000
Treasury stock acquired during period (shares)		500,000	700,000	6,300,000
Trade date fair value of shares acquired during period | $		$ 82,900	$ 50,100	$ 315,300
Number of shares authorized to be repurchased (shares)					10,000,000
Remaining number of shares authorized to be repurchased (shares)		8,000,000
Senior Notes | IAC
Class of Stock
Class of warrant outstanding (shares)		3,400,000	3,400,000
Exercise price of warrants (USD per share) | $ / shares		$ 229.70	$ 229.70
Proceeds from issuance of warrants | $	$ 23,600

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ 2,946,823	$ 2,010,670	$ 2,215,825
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	(25,102)	65,915	(42,088)
Amounts reclassified to earnings	(52)	(3,360)	6,937
Net current period other comprehensive (loss) income	(25,154)	62,555	(35,151)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			21,131
Balance at end of period	3,551,801	2,946,823	2,010,670
Tax benefit related to unrealized losses on available-for-sale securities			700
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(103,568)	(170,149)	(154,645)
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	(25,106)	65,908	(46,943)
Amounts reclassified to earnings	(52)	673	9,850
Net current period other comprehensive (loss) income	(25,158)	66,581	(37,093)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			21,589
Balance at end of period	(128,726)	(103,568)	(170,149)
Unrealized Gains On Available-For-Sale Securities
Accumulated Other Comprehensive Loss
Balance at beginning of period	0	4,026	2,542
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	4	7	4,855
Amounts reclassified to earnings	0	(4,033)	(2,913)
Net current period other comprehensive (loss) income	4	(4,026)	1,942
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			(458)
Balance at end of period	4	0	4,026
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at beginning of period	(103,568)	(166,123)	(152,103)
Balance at end of period	$ (128,722)	$ (103,568)	$ (166,123)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE LOSS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Tax (benefit) provision related to unrealized gains/losses on available-for-sale securities	$ 3.8	$ 0.2

EARNINGS (LOSS) PER SHARE - Sum

EARNINGS (LOSS) PER SHARE - Summary (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Oct. 02, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net earnings (loss)										$ 757,747	$ 358,008	$ (16,151)
Net earnings attributable to noncontrolling interests										(130,786)	(53,084)	(25,129)
Impact from public subsidiaries' dilutive securities										(25,228)	(33,531)	0
Net earnings (loss) attributable to IAC shareholders		$ 191,752	$ 145,774	$ 218,353	$ 71,082	$ 32,804	$ 179,643	$ 66,268	$ 26,209	626,961	304,924	(41,280)
Net earnings (loss) attributable to IAC shareholders										$ 601,733	$ 271,393	$ (41,280)
Weighted average basic shares outstanding (shares)										83,407	80,089	80,045
Dilutive securities including subsidiary denominated equity, stock options and RSUs (shares)										7,915	5,221	0
Weighted average diluted shares outstanding (shares)										91,322	85,310	80,045
Earnings (loss) per share attributable to IAC shareholders: Basic
Basic earnings (loss) per share (USD per share)		$ 2.29	$ 1.75	$ 2.61	$ 0.86	$ 0.40	$ 2.22	$ 0.84	$ 0.34	$ 7.52	$ 3.81	$ (0.52)
Earnings (loss) per share attributable to IAC shareholders: Diluted
Diluted earnings (loss) per share (USD per share)		$ 2.04	$ 1.49	$ 2.32	$ 0.71	$ 0.37	$ 1.79	$ 0.70	$ 0.29	6.59	$ 3.18	$ (0.52)
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (shares)												11,300
Exchange price (USD per share)										$ 152.18
RSUs
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (shares)										3,500	6,900
PSUs
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (shares)										100	100
Exchangeable Notes
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (shares)										300
IAC | Senior Notes
Anti-dilutive weighted average common shares
Exchange price (USD per share)	$ 152.18									$ 152.18

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Dec. 31, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2018USD ($)planinstallment$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015installment	Dec. 31, 2014	Dec. 31, 2008	Jul. 31, 2017shares
Share-based Compensation Arrangement by Share-based Payment Award
Number of active stock-based compensation plans | plan				2
Shares available for grant (shares) | shares	11,500			11,500
Unrecognized compensation cost, net of estimated forfeitures	$ 326,000			$ 326,000
Weighted-average period over which cost is expected to be recognized				2 years 3 months 18 days
Income tax benefit		$ (257,000)		$ (3,811)	$ 291,050	$ 64,934
Intrinsic value of stock options exercised				$ 83,700	$ 164,600	$ 17,100
Stock options granted in period (shares) | shares				80	1,200	1,700
Weighted average grant date fair value of stock options granted (USD per share) | $ / shares	$ 53.94			$ 53.94	$ 22.94	$ 12.34
Number of shares required to settle vested and unvested interests at fair value (shares) | shares				100
Cash required to settle vested and unvested interests at fair value				$ 16,000
Withholding rate (as a percent)				50.00%
Excess tax benefit attributable to stock-based compensation				$ 143,300	$ 361,800
Incremental compensation cost		6,600				$ 7,300
Incremental compensation cost from modification recognized in year of modification				$ 100	700	6,300
Modification forfeitures						7,100
2008 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Stated term (in years)									10 years
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Stated term (in years)								10 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period				4 years
Number of installments | installment				3
Proportion of installments (as a percent)				33.00%
Income tax benefit				$ 189,000	$ 423,000	$ 34,800
Expected volatility (as a percent)				27.00%	29.00%	29.00%
Risk-free interest rate (as a percent)				2.70%	2.00%	1.20%
Dividend yield (as a percent)				0.00%
Expected term				6 years 2 months 12 days	5 years 2 months 18 days	4 years 9 months 18 days
Cash received from stock option exercises				$ 41,700	$ 82,400	$ 25,800
Employee Stock Options, Net Settled
Share-based Compensation Arrangement by Share-based Payment Award
Income tax benefit				$ (169,000)	$ (411,600)	$ (63,400)
Market-Based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Number of installments | installment				2
Proportion of installments (as a percent)				50.00%
Vesting requirement, consecutive days above price threshold						20 days
Number of annual vesting installments | installment							2
Expected volatility (as a percent)						29.00%
Risk-free interest rate (as a percent)						2.80%
Dividend yield (as a percent)							0.00%
Expected term						1 year 9 months 18 days
Withholding rate (as a percent)				50.00%
Excess tax benefit attributable to stock-based compensation				$ 349,100
Market-Based Stock Options - Vested
Share-based Compensation Arrangement by Share-based Payment Award
Excess tax benefit attributable to stock-based compensation				221,600
Market-Based Stock Options - Unvested
Share-based Compensation Arrangement by Share-based Payment Award
Excess tax benefit attributable to stock-based compensation				$ 127,400
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award
Weighted average grant date fair value of RSUs and PSUs granted (USD per share) | $ / shares				$ 178.29	$ 90.04	$ 46.92
Fair value of RSUs and PSUs that vested during the period				$ 8,900	$ 32,500	$ 13,500
RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period				3 years
Weighted average grant date fair value of RSUs and PSUs granted (USD per share) | $ / shares				$ 183.33
PSUs
Share-based Compensation Arrangement by Share-based Payment Award
Weighted average grant date fair value of RSUs and PSUs granted (USD per share) | $ / shares				$ 152.53
Vesting period one | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				25.00%
Vesting period one | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				33.00%
Vesting period two | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				25.00%
Vesting period two | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				33.00%
Vesting period three | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				25.00%
Vesting period three | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				33.00%
Vesting period four | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights rate (as a percent)				25.00%
IAC
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued (shares) | shares	700			700						2,000
IAC | Tandem Awards
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued (shares) | shares	300			300
Match Group
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued (shares) | shares	2,500			2,500						11,300
Cash payments made to cover withholding taxes and exercise of awards					520,000
Vested equity awards settled in cash		$ 33,900	$ 13,400
Match Group | Market Based Awards
Share-based Compensation Arrangement by Share-based Payment Award
Withholding rate (as a percent)				50.00%
Stock issued in conversion (shares) | shares				9,700
Excess tax benefit attributable to stock-based compensation				$ 416,200
Match Group | Market Based Awards - Vested
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued in conversion (shares) | shares				1,700
Excess tax benefit attributable to stock-based compensation				$ 75,000
Match Group | Market Based Awards - Unvested
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued in conversion (shares) | shares				8,000
Excess tax benefit attributable to stock-based compensation				$ 341,200
Match Group | Tandem Awards
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued (shares) | shares	1,400			1,400
ANGI Homeservices
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares required to settle vested and unvested interests at fair value (shares) | shares	1,100
Cash required to settle vested and unvested interests at fair value	$ 205,900
Withholding rate (as a percent)	50.00%
Common stock issued (shares) | shares	12,800			12,800
Cash withholding obligation	$ 36,500			$ 36,500
Cash withholding obligation equivalent (shares) | shares	2,300			2,300
Incremental compensation cost				$ 7,900
Incremental compensation cost from modification recognized in year of modification				$ 3,900
ANGI Homeservices | PSUs
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares required to settle vested and unvested interests at fair value (shares) | shares				100
Cash required to settle vested and unvested interests at fair value				$ 10,400
Common stock issued (shares) | shares	600			600
ANGI Homeservices | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award
Incremental compensation cost				$ 217,700
Incremental compensation cost from modification recognized in year of modification				$ 56,900	$ 93,400

STOCK-BASED COMPENSATION - Chan

STOCK-BASED COMPENSATION - Changes in Outstanding Stock Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Balance at beginning of period (shares)	6,586
Granted (shares)	80	1,200	1,700
Exercised (shares)	(774)
Forfeited (shares)	(72)
Expired (shares)	(6)
Balance at end of period (shares)	5,814	6,586
Options exercisable (shares)	3,592
Weighted Average Exercise Price
Balance at beginning of period (USD per share)	$ 60.57
Granted (USD per share)	152.53
Exercised (USD per share)	52.56
Forfeited (USD per share)	57.52
Expired (USD per share)	19.51
Balance at end of period (USD per share)	62.97	$ 60.57
Options exercisable (USD per share)	$ 59.64
Weighted Average Remaining Contractual Term (In Years)
Remaining term at end of period	6 years 1 month 6 days
Term of options exercisable	5 years 3 months 18 days
Aggregate Intrinsic Value
Balance at end of period	$ 698,128
Options exercisable	$ 443,293

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Options Outstanding and Exercisable (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Options Outstanding
Options outstanding (shares) | shares	5,814
Weighted- Average Remaining Contractual Life in Years	6 years 1 month 6 days
Weighted-average exercise price (USD per share)	$ 62.97
Options Exercisable
Options exercisable (shares) | shares	3,592
Weighted- Average Remaining Contractual Life in Years	5 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 59.64
$20.01 to $30.00
Options Outstanding
Options outstanding (shares) | shares	30
Weighted- Average Remaining Contractual Life in Years	1 year 1 month 6 days
Weighted-average exercise price (USD per share)	$ 21.60
Options Exercisable
Options exercisable (shares) | shares	30
Weighted- Average Remaining Contractual Life in Years	1 year 1 month 6 days
Weighted-average exercise price (USD per share)	$ 21.60
$30.01 to $40.00
Options Outstanding
Options outstanding (shares) | shares	389
Weighted- Average Remaining Contractual Life in Years	2 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 32.30
Options Exercisable
Options exercisable (shares) | shares	389
Weighted- Average Remaining Contractual Life in Years	2 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 32.30
$40.01 to $50.00
Options Outstanding
Options outstanding (shares) | shares	1,541
Weighted- Average Remaining Contractual Life in Years	5 years 9 months 18 days
Weighted-average exercise price (USD per share)	$ 43.35
Options Exercisable
Options exercisable (shares) | shares	961
Weighted- Average Remaining Contractual Life in Years	5 years
Weighted-average exercise price (USD per share)	$ 44.26
$50.01 to $60.00
Options Outstanding
Options outstanding (shares) | shares	246
Weighted- Average Remaining Contractual Life in Years	3 years 2 months 12 days
Weighted-average exercise price (USD per share)	$ 59.85
Options Exercisable
Options exercisable (shares) | shares	244
Weighted- Average Remaining Contractual Life in Years	3 years 2 months 12 days
Weighted-average exercise price (USD per share)	$ 59.86
$60.01 to $70.00
Options Outstanding
Options outstanding (shares) | shares	1,173
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 65.27
Options Exercisable
Options exercisable (shares) | shares	767
Weighted- Average Remaining Contractual Life in Years	6 years
Weighted-average exercise price (USD per share)	$ 65.62
$70.01 to $80.00
Options Outstanding
Options outstanding (shares) | shares	1,840
Weighted- Average Remaining Contractual Life in Years	7 years 4 months 24 days
Weighted-average exercise price (USD per share)	$ 75.33
Options Exercisable
Options exercisable (shares) | shares	822
Weighted- Average Remaining Contractual Life in Years	6 years 9 months 18 days
Weighted-average exercise price (USD per share)	$ 74.72
$80.01 to $90.00
Options Outstanding
Options outstanding (shares) | shares	500
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 84.31
Options Exercisable
Options exercisable (shares) | shares	375
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 84.31
Greater than $90.01
Options Outstanding
Options outstanding (shares) | shares	95
Weighted- Average Remaining Contractual Life in Years	9 years 1 month 6 days
Weighted-average exercise price (USD per share)	$ 148.30
Options Exercisable
Options exercisable (shares) | shares	4
Weighted- Average Remaining Contractual Life in Years	8 years 10 months 24 days
Weighted-average exercise price (USD per share)	$ 125.08
Minimum | $20.01 to $30.00
Options Exercisable
Exercise price range, lower limit (USD per share)	20.01
Minimum | $30.01 to $40.00
Options Exercisable
Exercise price range, lower limit (USD per share)	30.01
Minimum | $40.01 to $50.00
Options Exercisable
Exercise price range, lower limit (USD per share)	40.01
Minimum | $50.01 to $60.00
Options Exercisable
Exercise price range, lower limit (USD per share)	50.01
Minimum | $60.01 to $70.00
Options Exercisable
Exercise price range, lower limit (USD per share)	60.01
Minimum | $70.01 to $80.00
Options Exercisable
Exercise price range, lower limit (USD per share)	70.01
Minimum | $80.01 to $90.00
Options Exercisable
Exercise price range, lower limit (USD per share)	80.01
Minimum | Greater than $90.01
Options Exercisable
Exercise price range, lower limit (USD per share)	90.01
Maximum | $20.01 to $30.00
Options Exercisable
Exercise price range, upper limit (USD per share)	30
Maximum | $30.01 to $40.00
Options Exercisable
Exercise price range, upper limit (USD per share)	40
Maximum | $40.01 to $50.00
Options Exercisable
Exercise price range, upper limit (USD per share)	50
Maximum | $50.01 to $60.00
Options Exercisable
Exercise price range, upper limit (USD per share)	60
Maximum | $60.01 to $70.00
Options Exercisable
Exercise price range, upper limit (USD per share)	70
Maximum | $70.01 to $80.00
Options Exercisable
Exercise price range, upper limit (USD per share)	80
Maximum | $80.01 to $90.00
Options Exercisable
Exercise price range, upper limit (USD per share)	$ 90

STOCK-BASED COMPENSATION - Weig

STOCK-BASED COMPENSATION - Weighted-Average Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award
Expected volatility (as a percent)	27.00%	29.00%	29.00%
Risk-free interest rate (as a percent)	2.70%	2.00%	1.20%
Expected term	6 years 2 months 12 days	5 years 2 months 18 days	4 years 9 months 18 days
Dividend yield (as a percent)	0.00%

STOCK-BASED COMPENSATION - Outs

STOCK-BASED COMPENSATION - Outstanding and Unvested RSUs and PSUs (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
RSUs
Number of Shares
Balance at beginning of the period (shares) | shares	360
Granted (shares) | shares	153
Vested (shares) | shares	(49)
Forfeited (shares) | shares	(5)
Balance at end of the period (shares) | shares	459
Weighted Average Grant Date Fair Value
Balance at beginning of the period (USD per share) | $ / shares	$ 80.81
Granted (USD per share) | $ / shares	183.33
Vested (USD per share) | $ / shares	78.54
Forfeited (USD per share) | $ / shares	98.81
Balance at end of the period (USD per share) | $ / shares	$ 115.12
Vesting period	3 years
PSUs
Number of Shares
Balance at beginning of the period (shares) | shares	130
Granted (shares) | shares	30
Vested (shares) | shares	0
Forfeited (shares) | shares	(17)
Balance at end of the period (shares) | shares	143
Weighted Average Grant Date Fair Value
Balance at beginning of the period (USD per share) | $ / shares	$ 76
Granted (USD per share) | $ / shares	152.53
Vested (USD per share) | $ / shares	0
Forfeited (USD per share) | $ / shares	76
Balance at end of the period (USD per share) | $ / shares	$ 92.02

SEGMENT INFORMATION - Segment R

SEGMENT INFORMATION - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenue									1,729,850	1,330,661	1,118,110
Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue									1,132,241	736,386	498,890
Operating Segments | Vimeo
Segment Reporting Information [Line Items]
Revenue									159,641	103,332	78,805
Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Revenue									130,991	90,890	77,913
Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenue									582,287	577,998	604,140
Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue									528,250	468,589	762,609
Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue									$ (368)	$ (617)	$ (585)

SEGMENT INFORMATION - Revenue D

SEGMENT INFORMATION - Revenue Disaggregated by Service (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenues									1,729,850	1,330,661	1,118,110
Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									1,132,241	736,386	498,890
Operating Segments | Vimeo
Segment Reporting Information [Line Items]
Revenues									159,641	103,332	78,805
Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Revenues									130,991	90,890	77,913
Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									582,287	577,998	604,140
Operating Segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenues									123,516	55,849	40,825
Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									528,250	468,589	762,609
North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									1,062,171	678,897	461,847
Europe | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									70,070	57,489	37,043
Direct | Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenues									1,677,171	1,281,249	1,067,364
Direct | Operating Segments | Match Group | Tinder
Segment Reporting Information [Line Items]
Revenues									805,316	403,216	168,522
Direct | Operating Segments | Match Group | Other brands
Segment Reporting Information [Line Items]
Revenues									871,855	878,033	898,842
Direct | North America | Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenues									902,478	741,334	673,944
Direct | All Other Countries | Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenues									774,693	539,915	393,420
Indirect | Operating Segments | Match Group
Segment Reporting Information [Line Items]
Revenues									52,679	49,412	50,746
Marketplace | North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									774,495	581,414	428,866
Consumer Connection | North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									704,341	521,481	382,466
Membership Subscription | North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									66,214	56,135	43,573
Other | North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									3,940	3,798	2,827
Advertising and Other | North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									287,676	97,483	32,981
Advertising and Other | Europe | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									1,795	884	983
Consumer Connection | Europe | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									50,913	40,009	28,124
Membership Subscription | Europe | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenues									17,362	16,596	7,936
Platform | Operating Segments | Vimeo
Segment Reporting Information [Line Items]
Revenues									146,665	99,650	78,805
Hardware | Operating Segments | Vimeo
Segment Reporting Information [Line Items]
Revenues									12,976	3,682	0
Advertising | Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Revenues									113,014	81,948	76,099
Advertising | Operating Segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenues									18,541	27,869	19,038
Advertising | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									424,485	279,487	344,200
Google Advertising | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									357,752	225,576	269,192
Other | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									66,733	53,911	75,008
Affiliate Commerce Commission | Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Revenues									14,458	7,372	1,685
Other | Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Revenues									3,519	1,570	129
Other | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									103,765	169,497	160,329
Desktop | Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									458,771	522,149	563,315
Advertising | Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									437,956	487,536	533,372
Google Advertising | Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									426,964	480,774	523,335
Other | Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									10,992	6,762	10,037
Subscription and Other | Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenues									20,815	34,613	29,943
Subscription and Other | Operating Segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenues									104,975	27,980	21,787
Test Preparation | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									0	19,605	86,517
Product
Segment Reporting Information [Line Items]
Revenues									13,665	4,302	172,408
Product | Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenues									$ 0	$ 0	$ 171,563

SEGMENT INFORMATION - Revenue a

SEGMENT INFORMATION - Revenue and Long-Lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue and Long-lived Assets by Geography
Revenue	$ 4,262,892	$ 3,307,239	$ 3,139,882
Long-lived assets (excluding goodwill and intangible assets)	318,800	315,170
United States
Revenue and Long-lived Assets by Geography
Revenue	2,824,928	2,323,050	2,318,976
Long-lived assets (excluding goodwill and intangible assets)	289,756	286,541
All other countries
Revenue and Long-lived Assets by Geography
Revenue	1,437,964	984,189	$ 820,906
Long-lived assets (excluding goodwill and intangible assets)	$ 29,044	$ 28,629

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Adjusted EBITDA to Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Other Significant Reconciling Item
Operating income	$ 133,920	$ 172,832	$ 168,437	$ 89,950	$ 94,360	$ (18,589)	$ 75,635	$ 37,060	$ 565,139	$ 188,466	$ (32,625)
Stock-based compensation expense									238,420	264,618	104,820
Depreciation									75,360	74,265	71,676
Amortization of intangibles									108,399	42,143	79,426
Goodwill Impairment									0	0	275,367
Interest expense									(109,327)	(105,295)	(109,110)
Other expense, net									305,746	(16,213)	60,650
Earnings (loss) before income taxes									761,558	66,958	(81,085)
Income tax benefit						(257,000)			(3,811)	291,050	64,934
Net earnings (loss)	217,477	171,577	280,854	87,839	23,349	225,639	80,557	28,463	757,747	358,008	(16,151)
Net earnings attributable to noncontrolling interests									(130,786)	(53,084)	(25,129)
Net earnings (loss) attributable to IAC shareholders	$ 191,752	$ 145,774	$ 218,353	$ 71,082	$ 32,804	$ 179,643	$ 66,268	$ 26,209	626,961	304,924	(41,280)
Operating Segments | Match Group
Segment Reporting, Other Significant Reconciling Item
Operating income									553,294	360,517	315,549
Stock-based compensation expense									66,031	69,090	52,370
Depreciation									32,968	32,613	27,726
Amortization of intangibles									1,318	1,468	16,932
Acquisition-related Contingent Consideration Fair Value Adjustments									320	5,253	(9,197)
Adjusted EBITDA									653,931	468,941	403,380
Goodwill Impairment											0
Operating Segments | ANGI Homeservices
Segment Reporting, Other Significant Reconciling Item
Operating income									63,906	(149,176)	25,363
Stock-based compensation expense									97,078	149,230	8,916
Depreciation									24,310	14,543	8,419
Amortization of intangibles									62,212	23,261	3,153
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									247,506	37,858	45,851
Goodwill Impairment											0
Operating Segments | Vimeo
Segment Reporting, Other Significant Reconciling Item
Operating income									(35,594)	(27,328)	(25,350)
Stock-based compensation expense									0	0	0
Depreciation									1,200	1,408	1,085
Amortization of intangibles									6,349	2,313	4,176
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	(192)
Adjusted EBITDA									(28,045)	(23,607)	(20,281)
Goodwill Impairment											0
Operating Segments | Dotdash
Segment Reporting, Other Significant Reconciling Item
Operating income									18,778	(15,694)	(248,705)
Stock-based compensation expense									0	0	0
Depreciation									969	2,255	2,775
Amortization of intangibles									1,637	10,676	30,754
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									21,384	(2,763)	(16,846)
Goodwill Impairment											198,330
Operating Segments | Applications
Segment Reporting, Other Significant Reconciling Item
Operating income									94,834	130,176	109,663
Stock-based compensation expense									0	0	0
Depreciation									2,601	3,863	5,095
Amortization of intangibles									33,266	2,170	5,483
Acquisition-related Contingent Consideration Fair Value Adjustments									1,136	548	12,035
Adjusted EBITDA									131,837	136,757	132,276
Goodwill Impairment											0
Operating Segments | Emerging & Other
Segment Reporting, Other Significant Reconciling Item
Operating income									29,964	17,412	(99,696)
Stock-based compensation expense									919	2,130	1,258
Depreciation									1,678	4,065	12,675
Amortization of intangibles									3,617	2,255	18,928
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	(91)
Adjusted EBITDA									36,178	25,862	10,111
Goodwill Impairment											77,037
Corporate
Segment Reporting, Other Significant Reconciling Item
Operating income									(160,043)	(127,441)	(109,449)
Stock-based compensation expense									74,392	44,168	42,276
Depreciation									11,634	15,518	13,901
Amortization of intangibles									0	0	0
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									$ (74,017)	$ (67,755)	(53,272)
Goodwill Impairment											$ 0

SEGMENT INFORMATION - Reconci_2

SEGMENT INFORMATION - Reconciliation of Segment Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item
Segment Assets	$ 3,132,718	$ 2,263,516
Long-lived assets (excluding goodwill and intangible assets)	318,800	315,170
Goodwill	2,726,859	2,559,066	$ 1,924,052
Indefinite-Lived Intangible Assets	458,104	459,143
Definite-Lived Intangible Assets, Net	173,318	204,594
Assets before deferred tax assets	6,809,799	5,801,489
Add: Deferred tax assets	64,786	66,321
TOTAL ASSETS	6,874,585	5,867,810
Match Group
Segment Reporting, Asset Reconciling Item
Goodwill	1,245,013	1,247,899	1,206,538
ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Goodwill	892,800	768,317	170,611
Applications
Segment Reporting, Asset Reconciling Item
Goodwill	504,892	447,242	447,242
Emerging & Other
Segment Reporting, Asset Reconciling Item
Goodwill	7,002	18,305	$ 90,012
Operating Segments | Match Group
Segment Reporting, Asset Reconciling Item
Segment Assets	377,965	467,338
Long-lived assets (excluding goodwill and intangible assets)	58,351	61,620
Goodwill	1,245,013	1,247,899
Indefinite-Lived Intangible Assets	230,684	228,296
Definite-Lived Intangible Assets, Net	6,956	2,049
Assets before deferred tax assets	1,918,969	2,007,202
Operating Segments | ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Segment Assets	497,327	264,450
Long-lived assets (excluding goodwill and intangible assets)	70,859	53,292
Goodwill	892,800	768,317
Indefinite-Lived Intangible Assets	171,486	153,447
Definite-Lived Intangible Assets, Net	132,809	175,124
Assets before deferred tax assets	1,765,281	1,414,630
Operating Segments | Vimeo
Segment Reporting, Asset Reconciling Item
Segment Assets	33,568	30,507
Long-lived assets (excluding goodwill and intangible assets)	1,014	1,972
Goodwill	77,152	77,303
Indefinite-Lived Intangible Assets	0	0
Definite-Lived Intangible Assets, Net	9,442	15,655
Assets before deferred tax assets	121,176	125,437
Operating Segments | Dotdash
Segment Reporting, Asset Reconciling Item
Segment Assets	39,276	27,190
Long-lived assets (excluding goodwill and intangible assets)	3,229	4,077
Goodwill	0	0
Indefinite-Lived Intangible Assets	13,500	6,000
Definite-Lived Intangible Assets, Net	1,514	3,152
Assets before deferred tax assets	57,519	40,419
Operating Segments | Applications
Segment Reporting, Asset Reconciling Item
Segment Assets	153,781	345,532
Long-lived assets (excluding goodwill and intangible assets)	4,867	7,004
Goodwill	504,892	447,242
Indefinite-Lived Intangible Assets	39,463	60,600
Definite-Lived Intangible Assets, Net	22,447	847
Assets before deferred tax assets	725,450	861,225
Operating Segments | Emerging & Other
Segment Reporting, Asset Reconciling Item
Segment Assets	95,858	255,107
Long-lived assets (excluding goodwill and intangible assets)	1,638	2,377
Goodwill	7,002	18,305
Indefinite-Lived Intangible Assets	2,971	10,800
Definite-Lived Intangible Assets, Net	150	7,767
Assets before deferred tax assets	107,619	294,356
Corporate
Segment Reporting, Asset Reconciling Item
Segment Assets	1,934,943	873,392
Long-lived assets (excluding goodwill and intangible assets)	178,842	184,828
Goodwill	0	0
Indefinite-Lived Intangible Assets	0	0
Definite-Lived Intangible Assets, Net	0	0
Assets before deferred tax assets	$ 2,113,785	$ 1,058,220

SEGMENT INFORMATION - Capital E

SEGMENT INFORMATION - Capital Expenditures by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Capital expenditures	$ 85,634	$ 75,523	$ 78,039
Operating Segments | Match Group
Segment Reporting Information [Line Items]
Capital expenditures	30,954	28,833	46,098
Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Capital expenditures	46,976	26,837	16,660
Operating Segments | Vimeo
Segment Reporting Information [Line Items]
Capital expenditures	209	109	1,959
Operating Segments | Dotdash
Segment Reporting Information [Line Items]
Capital expenditures	102	825	1,671
Operating Segments | Applications
Segment Reporting Information [Line Items]
Capital expenditures	111	227	1,196
Operating Segments | Emerging & Other
Segment Reporting Information [Line Items]
Capital expenditures	1,119	852	6,683
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	$ 6,163	$ 17,840	$ 3,772

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Future Minimum Payments under Operation Lease Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future Minimum Payments Under Operating Lease Agreements
2,019	$ 38,770
2,020	46,440
2,021	40,998
2,022	34,066
2,023	30,567
Thereafter	255,563
Total	446,404
Expenses charged to operations under operating lease agreements	$ 42,000	$ 37,900	$ 50,800
Proportion of most significant operating leases (as a percent)	61.00%

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Commercial Commitments Outstanding (Details) $ in Thousands	Dec. 31, 2018USD ($)
Other Commitments
Less Than 1 Year	$ 40,877
1-3 Years	23,897
3-5 Years	0
More Than 5 Years	2,272
Total Amounts Committed	67,046
Purchase obligations
Other Commitments
Less Than 1 Year	40,428
1-3 Years	23,897
3-5 Years	0
More Than 5 Years	0
Total Amounts Committed	64,325
Letters of credit and surety bonds
Other Commitments
Less Than 1 Year	449
1-3 Years	0
3-5 Years	0
More Than 5 Years	2,272
Total Amounts Committed	$ 2,721

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - Tinder Optionholder Litigation $ in Billions	Aug. 31, 2018plaintiff	Aug. 14, 2018USD ($)plaintiff
Loss Contingencies [Line Items]
Number of plaintiffs	6	10
Number of plaintiffs who filed a discontinuance of claims	4
Pending Litigation
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value | $		$ 2

SUPPLEMENTAL CASH FLOW INFORM_3

SUPPLEMENTAL CASH FLOW INFORMATION - Summary (Details) - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 19, 2018	Sep. 29, 2017
Debt Instrument
Fair value of contingent consideration liabilities	$ 25,500,000	$ 0	$ 200,000
Cash paid (received) during the year for:
Interest	90,485,000	92,461,000	107,360,000
Income tax payments	45,154,000	35,598,000	69,103,000
Income tax refunds	$ (33,698,000)	$ (42,025,000)	$ (23,877,000)
Common Stock
Debt Instrument
Common stock issued (shares)	262,303	260,624
Common stock	$ 262,000	$ 261,000
ANGI Homeservices
Debt Instrument
Common stock issued (shares)	12,800
ANGI Homeservices | Common Stock
Debt Instrument
Common stock issued (shares)				8,600	61,300
Common stock				$ 165,800,000	$ 763,700,000

RELATED PARTY TRANSACTIONS - Na

RELATED PARTY TRANSACTIONS - Narrative (Details) shares in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)shares	Dec. 31, 2018USD ($)aircraftshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Sep. 29, 2017USD ($)intercompany_note
Match Group | Employee Matters Agreement
Related Party Transaction [Line Items]
Shares received from related party pursuant to employee matters agreement (in shares) | shares			3	11.9	1
Shares received from related party as reimbursement for exercise and settlement of equity awards denominated in shares of subsidiary (in shares) | shares			2.5	11.3	0.5
Shares received from related party as reimbursement for exercise and vesting of equity awards denominated in shares of parent (in shares) | shares			0.5	0.6	0.4
Match Group | Services Agreement
Related Party Transaction [Line Items]
Payments received from related parties			$ 7,600,000	$ 9,900,000	$ 11,800,000
Match Group | Leased Office Space
Related Party Transaction [Line Items]
Expenses from transactions with related parties			5,200,000	5,100,000	$ 4,300,000
Match Group | Tax Sharing Agreement
Related Party Transaction [Line Items]
Payments received from related parties			7,000,000	10,900,000
Amounts due to related parties		$ 7,300,000	0	7,300,000
Match Group | Net Operating Loss Sold
Related Party Transaction [Line Items]
Expenses from transactions with related parties			900,000
ANGI Homeservices
Related Party Transaction [Line Items]
Current accounts receivable due from related party		$ 2,000,000	$ 0	2,000,000
ANGI Homeservices | Employee Matters Agreement
Related Party Transaction [Line Items]
Shares received from related party pursuant to employee matters agreement (in shares) | shares		0.4	0.9
ANGI Homeservices | Services Agreement
Related Party Transaction [Line Items]
Payments received from related parties		$ 1,700,000	$ 5,700,000	$ 400,000
Amounts due to related parties			100,000
ANGI Homeservices | Tax Sharing Agreement
Related Party Transaction [Line Items]
Current notes receivable due from related party			12,100,000
Payments received from related party tax expense			$ 0
ANGI Homeservices | Intercompany Notes
Related Party Transaction [Line Items]
Number of related party debt instruments | intercompany_note						2
ANGI Homeservices | Payoff Intercompany Note
Related Party Transaction [Line Items]
Current notes receivable due from related party						$ 61,500,000
ANGI Homeservices | Working Capital Intercompany Note
Related Party Transaction [Line Items]
Current notes receivable due from related party						$ 15,000,000
Other Affiliates
Related Party Transaction [Line Items]
Ownership interest held by each of the Company and Expedia in aircraft (as a percent)			50.00%
Number of aircraft operated | aircraft			2
IAC's total purchase price and refurbish costs in aircraft	$ 17,400,000
Percentage of total purchase price and refurbish costs paid in related party transaction	50.00%
Ownership interest held by each of the Company and Expedia in an entity employing aircraft flight crew (as a percent)			50.00%
Class B Common Stock | ANGI Homeservices | Angie's List Merger Agreement
Related Party Transaction [Line Items]
Stock received from related party (shares) | shares			5.1

BENEFIT PLANS - Narrative (Deta

BENEFIT PLANS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employee contribution limit per calendar year (up to) (as a percent of pre-tax earnings)	50.00%
Employer contribution limit per calendar year (as a percent of compensation)	3.00%
Employer contribution per dollar employee contributes up to contribution limit	50.00%
United States
Defined Contribution Plan Disclosure
Defined contribution plan contributions	$ 12.9	$ 11.1	$ 10
All Other Countries
Defined Contribution Plan Disclosure
Defined contribution plan contributions	$ 3.4	$ 2.5	$ 2.1

CONSOLIDATED FINANCIAL STATEM_3

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 04, 2017
Additional consolidated financial statement details
Unrealized gains, net, on equity securities held		$ 124,170
Term Loan | Match Group | Match Group Term Loan due November 16, 2022
Additional consolidated financial statement details
Repayment of debt				$ 440,000
Senior Notes | 4.875% Senior Notes due November 30, 2018 (the 4.875% Senior Notes); interest payable each May 30 and November 30
Additional consolidated financial statement details
Stated interest rate (as a percent)	4.75%	4.75%	4.875%	4.875%
Senior Notes | 4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15
Additional consolidated financial statement details
Stated interest rate (as a percent)	4.75%	4.75%
Senior Notes | Match Group | 6.75% Senior Notes due December 15, 2022 (the Match Group 6.75% Senior Notes); interest payable each June 15 and December 15
Additional consolidated financial statement details
Stated interest rate (as a percent)			6.75%		6.75%
Other Income (Expense)
Additional consolidated financial statement details
Interest income		$ 30,400	$ 11,400	$ 5,100
Gain on sale of long-term investments		27,900	34,900	3,600
Foreign currency exchange gain (loss)		5,300	16,800	34,400
Cost of repricing debt			(15,400)
Gain (loss) on mark-to-market adjustment			13,000	(2,500)
Write-off of proportionate share of original issue discount and deferred financing costs			(1,200)	(12,100)
Other Income (Expense) | Senior Notes
Additional consolidated financial statement details
Loss on redemption and repurchase of 2012 and 2013 Senior Notes				(3,600)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Dictionary.com, Electus, Felix, and CityGrid
Additional consolidated financial statement details
Gain on sale of business	$ 92,500
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Dictionary.com, Electus, Felix, and CityGrid | Other Income (Expense)
Additional consolidated financial statement details
Gain on sale of business		$ 120,600
Disposal Group, Disposed of by Sale, Not Discontinued Operations | The Princeton Review | Other Income (Expense)
Additional consolidated financial statement details
Gain on other-than-temporary impairment charges			$ 12,200
Disposal Group, Disposed of by Sale, Not Discontinued Operations | ShoeBuy | Other Income (Expense)
Additional consolidated financial statement details
Gain on sale of business				37,500
Disposal Group, Disposed of by Sale, Not Discontinued Operations | PriceRunner | Other Income (Expense)
Additional consolidated financial statement details
Gain on sale of business				12,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | ASKfm | Other Income (Expense)
Additional consolidated financial statement details
Gain on other-than-temporary impairment charges				(10,700)
Gain on sale of business				$ 3,800

CONSOLIDATED FINANCIAL STATEM_4

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other current assets:
Capitalized costs to obtain a contract with a customer	$ 69,817	$ 0
Prepaid expenses	55,586	49,350
Capitalized downloadable search toolbar costs, net	33,365	31,588
Income taxes receivable	10,132	33,239
Production costs	2,260	18,570
Other	57,093	52,627
Other current assets	$ 228,253	$ 185,374

CONSOLIDATED FINANCIAL STATEM_5

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	$ 605,598	$ 586,981
Accumulated depreciation and amortization	(286,798)	(271,811)
Property and equipment, net of accumulated depreciation and amortization	318,800	315,170
Buildings and leasehold improvements
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	249,026	246,038
Computer equipment and capitalized software
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	229,083	218,529
Furniture and other equipment
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	86,694	88,930
Projects in progress
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	29,204	19,094
Land
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	$ 11,591	$ 14,390

CONSOLIDATED FINANCIAL STATEM_6

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued expenses and other current liabilities:
Accrued employee compensation and benefits	$ 137,583	$ 108,431
Accrued advertising expense	105,520	96,445
Other	191,783	162,048
Accrued expenses and other current liabilities	$ 434,886	$ 366,924

CONSOLIDATED FINANCIAL STATEM_7

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Service revenue
Disaggregation of Revenue [Line Items]
Revenue									4,249,227	3,302,937	2,967,474
Product revenue
Disaggregation of Revenue [Line Items]
Revenue									$ 13,665	$ 4,302	$ 172,408

CONSOLIDATED FINANCIAL STATEM_8

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Cost of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cost of revenue:
Cost of service revenue									$ 898,736	$ 647,226	$ 617,058
Cost of product revenue									12,410	3,782	138,672
Cost of revenue	$ 253,722	$ 237,238	$ 218,224	$ 201,962	$ 199,727	$ 166,290	$ 139,033	$ 145,958	$ 911,146	$ 651,008	$ 755,730

CONSOLIDATED FINANCIAL STATEM_9

CONSOLIDATED FINANCIAL STATEMENT DETAILS - Other (Expense) Income, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other income (expense), net:
Other income (expense), net	$ 305,746	$ (16,213)	$ 60,650

TRANSACTION AND INTEGRATION R_3

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Stock-based compensation expense	$ 238,420	$ 264,618	$ 104,820
ANGI Homeservices
Business Acquisition [Line Items]
Transaction and integration related costs	3,584	44,101
Write-off due to deferred revenue	5,500	7,800
Stock-based compensation expense	$ 70,645	$ 122,066

TRANSACTION AND INTEGRATION R_4

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Stock-based compensation expense	$ 238,420	$ 264,618	$ 104,820
Cost of revenue
Business Acquisition [Line Items]
Stock-based compensation expense	2,482	1,881	2,305
Selling and marketing expense
Business Acquisition [Line Items]
Stock-based compensation expense	7,943	31,318	6,000
General and administrative expense
Business Acquisition [Line Items]
Stock-based compensation expense	188,510	192,957	77,151
Product development expense
Business Acquisition [Line Items]
Stock-based compensation expense	39,485	38,462	19,364
ANGI Homeservices
Business Acquisition [Line Items]
Transaction and integration related costs	3,584	44,101
Stock-based compensation expense	70,645	122,066
Total	74,229	166,167
Accrual for Business Combination [Roll Forward]
Accrual as of January 1	8,480	0
Costs incurred	3,584	44,101
Payments made	(12,064)	(35,621)
Accrual as of December 31	0	8,480	$ 0
ANGI Homeservices | Cost of revenue
Business Acquisition [Line Items]
Transaction and integration related costs	0	0
Stock-based compensation expense	0	0
Total	0	0
ANGI Homeservices | Selling and marketing expense
Business Acquisition [Line Items]
Transaction and integration related costs	0	7,430
Stock-based compensation expense	2,161	24,416
Total	2,161	31,846
ANGI Homeservices | General and administrative expense
Business Acquisition [Line Items]
Transaction and integration related costs	3,584	36,120
Stock-based compensation expense	61,010	83,420
Total	64,594	119,540
ANGI Homeservices | Product development expense
Business Acquisition [Line Items]
Transaction and integration related costs	0	551
Stock-based compensation expense	7,474	14,230
Total	$ 7,474	$ 14,781

GUARANTOR AND NON-GUARANTOR F_3

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Narrative (Details) - Senior Notes - 4.875% Senior Notes due November 30, 2018 (the 4.875% Senior Notes); interest payable each May 30 and November 30	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (as a percent)	4.75%	4.875%	4.875%
Proportion of voting interests acquired (as a percent)	100.00%

GUARANTOR AND NON-GUARANTOR F_4

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet
Cash and cash equivalents	$ 2,131,632	$ 1,630,809	$ 1,329,187	$ 1,481,447
Marketable securities	123,665	4,995
Accounts receivable, net of allowance and reserves	279,189	304,027
Other current assets	228,253	185,374
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization	318,800	315,170
Goodwill	2,726,859	2,559,066	$ 1,924,052
Intangible assets, net of accumulated amortization	631,422	663,737
Investment in subsidiaries	0	0
Other non-current assets	434,765	204,632
TOTAL ASSETS	6,874,585	5,867,810
Current portion of long-term debt	13,750	13,750
Accounts payable, trade	74,907	76,571
Other current liabilities	794,901	709,407
Long-term debt, net	2,245,548	1,979,469
Income taxes payable	37,584	25,624
Intercompany liabilities	0	0
Other long-term liabilities	90,407	73,299
Redeemable noncontrolling interests	65,687	42,867
Shareholders' equity (deficit)	2,843,125	2,430,028
Noncontrolling interests	708,676	516,795
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	6,874,585	5,867,810
Eliminations
Condensed Balance Sheet
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable, net of allowance and reserves	0	0
Other current assets	0	0
Intercompany receivables	(1,423,456)	(668,703)
Property and equipment, net of accumulated depreciation and amortization	0	0
Goodwill	0	0
Intangible assets, net of accumulated amortization	0	0
Investment in subsidiaries	(2,112,218)	(2,632,896)
Other non-current assets	(185,629)	(132,435)
TOTAL ASSETS	(3,721,303)	(3,434,034)
Current portion of long-term debt	0	0
Accounts payable, trade	0	0
Other current liabilities	0	0
Long-term debt, net	0	0
Income taxes payable	0	0
Intercompany liabilities	(1,423,456)	(668,703)
Other long-term liabilities	(185,629)	(132,435)
Redeemable noncontrolling interests	0	0
Shareholders' equity (deficit)	(2,112,218)	(2,632,896)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(3,721,303)	(3,434,034)
IAC
Condensed Balance Sheet
Long-term debt, net	484,666	468,461
IAC | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	1,018,082	585,639
Marketable securities	98,299	4,995
Accounts receivable, net of allowance and reserves	0	31
Other current assets	27,349	49,159
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization	6,526	2,811
Goodwill	0	0
Intangible assets, net of accumulated amortization	0	0
Investment in subsidiaries	1,897,699	2,077,898
Other non-current assets	274,789	170,073
TOTAL ASSETS	3,322,744	2,890,606
Current portion of long-term debt	0	0
Accounts payable, trade	1,304	5,163
Other current liabilities	41,721	29,489
Long-term debt, net	34,262	34,572
Income taxes payable	15	16
Intercompany liabilities	402,056	390,827
Other long-term liabilities	261	511
Redeemable noncontrolling interests	0	0
Shareholders' equity (deficit)	2,843,125	2,430,028
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,322,744	2,890,606
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable, net of allowance and reserves	99,970	109,289
Other current assets	29,222	33,387
Intercompany receivables	1,423,456	668,703
Property and equipment, net of accumulated depreciation and amortization	163,281	174,323
Goodwill	412,009	412,010
Intangible assets, net of accumulated amortization	43,914	74,852
Investment in subsidiaries	214,519	554,998
Other non-current assets	94,290	87,306
TOTAL ASSETS	2,480,661	2,114,868
Current portion of long-term debt	0	0
Accounts payable, trade	36,293	30,469
Other current liabilities	95,405	88,050
Long-term debt, net	0	0
Income taxes payable	1,707	1,605
Intercompany liabilities	0	0
Other long-term liabilities	18,181	18,613
Redeemable noncontrolling interests	0	0
Shareholders' equity (deficit)	2,329,075	1,976,131
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,480,661	2,114,868
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	1,113,550	1,045,170
Marketable securities	25,366	0
Accounts receivable, net of allowance and reserves	179,219	194,707
Other current assets	171,682	102,828
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization	148,993	138,036
Goodwill	2,314,850	2,147,056
Intangible assets, net of accumulated amortization	587,508	588,885
Investment in subsidiaries	0	0
Other non-current assets	251,315	79,688
TOTAL ASSETS	4,792,483	4,296,370
Current portion of long-term debt	13,750	13,750
Accounts payable, trade	37,310	40,939
Other current liabilities	657,775	591,868
Long-term debt, net	2,211,286	1,944,897
Income taxes payable	35,862	24,003
Intercompany liabilities	1,021,400	277,876
Other long-term liabilities	257,594	186,610
Redeemable noncontrolling interests	65,687	42,867
Shareholders' equity (deficit)	(216,857)	656,765
Noncontrolling interests	708,676	516,795
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 4,792,483	$ 4,296,370

GUARANTOR AND NON-GUARANTOR F_5

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Condensed Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Statements of Operations
Revenue	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	253,722	237,238	218,224	201,962	199,727	166,290	139,033	145,958	911,146	651,008	755,730
Selling and marketing expense									1,519,440	1,381,221	1,247,097
General and administrative expense									774,079	719,257	530,446
Product development expense									309,329	250,879	212,765
Depreciation									75,360	74,265	71,676
Amortization of intangibles									108,399	42,143	79,426
Goodwill impairment									0	0	275,367
Total operating costs and expenses									3,697,753	3,118,773	3,172,507
Operating income (loss)	133,920	172,832	168,437	89,950	94,360	(18,589)	75,635	37,060	565,139	188,466	(32,625)
Equity in earnings of unconsolidated affiliates									0	0	0
Interest expense									(109,327)	(105,295)	(109,110)
Other income (expense), net									305,746	(16,213)	60,650
Earnings (loss) before income taxes									761,558	66,958	(81,085)
Income tax (provision) benefit						(257,000)			(3,811)	291,050	64,934
Net earnings (loss)	217,477	171,577	280,854	87,839	23,349	225,639	80,557	28,463	757,747	358,008	(16,151)
Net earnings attributable to noncontrolling interests									(130,786)	(53,084)	(25,129)
Net earnings (loss) attributable to IAC shareholders	$ 191,752	$ 145,774	$ 218,353	$ 71,082	$ 32,804	$ 179,643	$ 66,268	$ 26,209	626,961	304,924	(41,280)
Comprehensive income attributable to IAC shareholders									601,683	367,370	(76,431)
Foreign cash repatriated									396,200
Eliminations
Condensed Statements of Operations
Revenue									(378)	(617)	(605)
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									(291)	(505)	(412)
Selling and marketing expense									(150)	(519)	(323)
General and administrative expense									69	407	130
Product development expense									(6)	0	0
Depreciation									0	0	0
Amortization of intangibles									0	0	0
Goodwill impairment											0
Total operating costs and expenses									(378)	(617)	(605)
Operating income (loss)									0	0	0
Equity in earnings of unconsolidated affiliates									(751,917)	(439,904)	(56,319)
Interest expense									0	0	0
Other income (expense), net									(378,438)	0	0
Earnings (loss) before income taxes									(1,130,355)	(439,904)	(56,319)
Income tax (provision) benefit									0	0	0
Net earnings (loss)									(1,130,355)	(439,904)	(56,319)
Net earnings attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									(1,130,355)	(439,904)	(56,319)
Comprehensive income attributable to IAC shareholders									(1,116,998)	(505,661)	(2,545)
IAC | Reportable Legal Entities
Condensed Statements of Operations
Revenue									0	0	0
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									195	160	859
Selling and marketing expense									977	1,250	2,353
General and administrative expense									141,727	100,237	89,583
Product development expense									2,003	2,421	4,807
Depreciation									1,203	1,564	1,610
Amortization of intangibles									0	0	0
Goodwill impairment											0
Total operating costs and expenses									146,105	105,632	99,212
Operating income (loss)									(146,105)	(105,632)	(99,212)
Equity in earnings of unconsolidated affiliates									731,834	419,149	49,545
Interest expense									(1,700)	(20,339)	(26,876)
Other income (expense), net									(18,834)	(30,787)	(1,879)
Earnings (loss) before income taxes									565,195	262,391	(78,422)
Income tax (provision) benefit									61,766	42,533	37,142
Net earnings (loss)									626,961	304,924	(41,280)
Net earnings attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									626,961	304,924	(41,280)
Comprehensive income attributable to IAC shareholders									601,683	367,370	(76,431)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statements of Operations
Revenue									850,475	753,858	960,000
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									262,912	159,488	297,712
Selling and marketing expense									313,769	353,186	417,051
General and administrative expense									49,563	62,340	83,636
Product development expense									56,431	55,232	69,778
Depreciation									12,497	20,668	26,514
Amortization of intangibles									29,437	11,213	41,157
Goodwill impairment											253,245
Total operating costs and expenses									724,609	662,127	1,189,093
Operating income (loss)									125,866	91,731	(229,093)
Equity in earnings of unconsolidated affiliates									20,083	20,755	6,774
Interest expense									0	0	0
Other income (expense), net									503,261	28,434	10,209
Earnings (loss) before income taxes									649,210	140,920	(212,110)
Income tax (provision) benefit									(56,612)	(119,957)	77,851
Net earnings (loss)									592,598	20,963	(134,259)
Net earnings attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									592,598	20,963	(134,259)
Comprehensive income attributable to IAC shareholders									601,232	7,629	(142,494)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statements of Operations
Revenue									3,412,795	2,553,998	2,180,487
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									648,330	491,865	457,571
Selling and marketing expense									1,204,844	1,027,304	828,016
General and administrative expense									582,720	556,273	357,097
Product development expense									250,901	193,226	138,180
Depreciation									61,660	52,033	43,552
Amortization of intangibles									78,962	30,930	38,269
Goodwill impairment											22,122
Total operating costs and expenses									2,827,417	2,351,631	1,884,807
Operating income (loss)									585,378	202,367	295,680
Equity in earnings of unconsolidated affiliates									0	0	0
Interest expense									(107,627)	(84,956)	(82,234)
Other income (expense), net									199,757	(13,860)	52,320
Earnings (loss) before income taxes									677,508	103,551	265,766
Income tax (provision) benefit									(8,965)	368,474	(50,059)
Net earnings (loss)									668,543	472,025	215,707
Net earnings attributable to noncontrolling interests									(130,786)	(53,084)	(25,129)
Net earnings (loss) attributable to IAC shareholders									537,757	418,941	190,578
Comprehensive income attributable to IAC shareholders									515,766	$ 498,032	$ 145,039
Foreign cash repatriated									$ 25,200

GUARANTOR AND NON-GUARANTOR F_6

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	Oct. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		$ 988,128	$ 416,699	$ 344,238
Cash flows from investing activities:
Acquisitions, net of cash acquired		(64,496)	(146,553)	(18,403)
Capital expenditures		(85,634)	(75,523)	(78,039)
Proceeds from maturities and sales of marketable debt securities		333,600	114,350	252,369
Purchases of marketable debt securities		(449,676)	(29,891)	(313,943)
Investments in time deposits		0	0	(87,500)
Proceeds from maturities of time deposits		0	0	87,500
Net proceeds from the sale of businesses and investments		136,719	185,778	172,228
Purchases of investments		(52,980)	(9,106)	(12,565)
Intercompany				0
Other, net		9,027	2,994	11,215
Net cash (used in) provided by investing activities		(173,440)	42,049	12,862
Cash flows from financing activities:
Purchase of exchangeable note hedge		0	(74,365)	0
Proceeds from issuance of warrants	$ 23,600	0	23,650	0
Debt issuance costs		(5,449)	(33,744)	(7,811)
Dividends paid to Match Group noncontrolling interests		(105,126)	0	0
Purchase of noncontrolling interests		(16,063)	(15,439)	(2,740)
Acquisition-related contingent consideration payments		(185)	(27,289)	(2,180)
Intercompany		0	0	0
Other, net		(5,375)	(5,000)	(2,705)
Net cash used in financing activities		(312,798)	(196,869)	(492,140)
Total cash provided (used)		501,890	261,879	(135,040)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		(1,887)	11,604	(6,434)
Net increase (decrease) in cash, cash equivalents, and restricted cash		500,003	273,483	(141,474)
Cash, cash equivalents, and restricted cash at beginning of period		1,633,682	1,360,199	1,501,673
Cash, cash equivalents, and restricted cash at end of period		2,133,685	1,633,682	1,360,199
Eliminations
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		(378,860)		0
Cash flows from investing activities:
Acquisitions, net of cash acquired		0		0
Capital expenditures		0		0
Proceeds from maturities and sales of marketable debt securities		0		0
Purchases of marketable debt securities		0		0
Investments in time deposits				0
Proceeds from maturities of time deposits				0
Net proceeds from the sale of businesses and investments		0		0
Purchases of investments		0		0
Intercompany				155,104
Other, net		0		0
Net cash (used in) provided by investing activities		0		155,104
Cash flows from financing activities:
Debt issuance costs		0		0
Dividends paid to Match Group noncontrolling interests		0
Acquisition-related contingent consideration payments		0		0
Intercompany		378,860		(155,104)
Other, net		0		0
Net cash used in financing activities		378,860		(155,104)
Total cash provided (used)		0
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		0		0
Net increase (decrease) in cash, cash equivalents, and restricted cash		0		0
Cash, cash equivalents, and restricted cash at beginning of period		0	0	0
Cash, cash equivalents, and restricted cash at end of period		0	0	0
IAC | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		(38,737)	(52,582)	(62,686)
Cash flows from investing activities:
Acquisitions, net of cash acquired		(4,142)	0	0
Capital expenditures		(5,274)	(337)	(479)
Proceeds from maturities and sales of marketable debt securities		298,600	114,350	252,369
Purchases of marketable debt securities		(390,005)	(29,891)	(313,943)
Investments in time deposits				0
Proceeds from maturities of time deposits				0
Net proceeds from the sale of businesses and investments		408	1,266	73,843
Purchases of investments		(39,180)	0	0
Intercompany				(155,104)
Other, net		(5,000)	0	126
Net cash (used in) provided by investing activities		(144,593)	85,388	(143,188)
Cash flows from financing activities:
Purchase of exchangeable note hedge			0
Proceeds from issuance of warrants			23,650
Debt issuance costs		0	0	0
Dividends paid to Match Group noncontrolling interests		0
Purchase of noncontrolling interests				(1,400)
Acquisition-related contingent consideration payments		0	0	0
Intercompany		673,308	416,396	122,965
Other, net		2,674	251	(313)
Net cash used in financing activities		615,446	(21,026)	(315,000)
Total cash provided (used)		432,116	11,780	(520,874)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		327	75	0
Net increase (decrease) in cash, cash equivalents, and restricted cash		432,443	11,855	(520,874)
Cash, cash equivalents, and restricted cash at beginning of period		585,639	573,784	1,094,658
Cash, cash equivalents, and restricted cash at end of period		1,018,082	585,639	573,784
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		583,498	131,700	128,503
Cash flows from investing activities:
Acquisitions, net of cash acquired		(50,530)	(2,550)	0
Capital expenditures		(1,396)	(1,169)	(5,792)
Proceeds from maturities and sales of marketable debt securities		0	0	0
Purchases of marketable debt securities		0	0	0
Investments in time deposits				0
Proceeds from maturities of time deposits				0
Net proceeds from the sale of businesses and investments		87,254	0	1,779
Purchases of investments		0	0	0
Intercompany				0
Other, net		7,451	1,944	910
Net cash (used in) provided by investing activities		42,779	(1,775)	(3,103)
Cash flows from financing activities:
Purchase of exchangeable note hedge			0
Proceeds from issuance of warrants			0
Debt issuance costs		0	0	0
Dividends paid to Match Group noncontrolling interests		0
Acquisition-related contingent consideration payments		0	0	(351)
Intercompany		(625,338)	(129,925)	(122,965)
Other, net		(939)	0	(2,084)
Net cash used in financing activities		(626,277)	(129,925)	(125,400)
Total cash provided (used)		0
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		0	0	0
Net increase (decrease) in cash, cash equivalents, and restricted cash		0	0	0
Cash, cash equivalents, and restricted cash at beginning of period		0	0	0
Cash, cash equivalents, and restricted cash at end of period		0	0	0
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		822,227	337,581	278,421
Cash flows from investing activities:
Acquisitions, net of cash acquired		(9,824)	(144,003)	(18,403)
Capital expenditures		(78,964)	(74,017)	(71,768)
Proceeds from maturities and sales of marketable debt securities		35,000	0	0
Purchases of marketable debt securities		(59,671)	0	0
Investments in time deposits				(87,500)
Proceeds from maturities of time deposits				87,500
Net proceeds from the sale of businesses and investments		49,057	184,512	96,606
Purchases of investments		(13,800)	(9,106)	(12,565)
Intercompany				0
Other, net		6,576	1,050	10,179
Net cash (used in) provided by investing activities		(71,626)	(41,564)	4,049
Cash flows from financing activities:
Purchase of exchangeable note hedge			(74,365)
Proceeds from issuance of warrants			0
Debt issuance costs		(5,449)	(33,744)	(7,811)
Dividends paid to Match Group noncontrolling interests		(105,126)
Purchase of noncontrolling interests		(16,063)	(15,439)	(1,340)
Acquisition-related contingent consideration payments		(185)	(27,289)	(1,829)
Intercompany		(426,830)	(286,471)	155,104
Other, net		(7,110)	(5,251)	(308)
Net cash used in financing activities		(680,827)	(45,918)	103,364
Total cash provided (used)		69,774	250,099	385,834
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		(2,214)	11,529	(6,434)
Net increase (decrease) in cash, cash equivalents, and restricted cash		67,560	261,628	379,400
Cash, cash equivalents, and restricted cash at beginning of period		1,048,043	786,415	407,015
Cash, cash equivalents, and restricted cash at end of period		1,115,603	1,048,043	786,415
IAC/InterActiveCorp
Cash flows from financing activities:
Proceeds from issuance of debt		0	517,500	0
Repurchases of IAC debt		(363)	(393,464)	(126,409)
Purchase of treasury stock		(82,891)	(56,424)	(308,948)
Proceeds from the exercise of stock options		41,700	82,397	25,821
Withholding taxes paid on behalf of employees on net settled stock-based awards		(18,982)	(93,832)	(26,716)
IAC/InterActiveCorp | Eliminations
Cash flows from financing activities:
Repurchases of IAC debt		0		0
Purchase of treasury stock		0		0
Proceeds from the exercise of stock options		0		0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0		0
IAC/InterActiveCorp | IAC | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt			0
Repurchases of IAC debt		(363)	(393,464)	(126,409)
Purchase of treasury stock		(82,891)	(56,424)	(308,948)
Proceeds from the exercise of stock options		41,700	82,397	25,821
Withholding taxes paid on behalf of employees on net settled stock-based awards		(18,982)	(93,832)	(26,716)
IAC/InterActiveCorp | Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt			0
Repurchases of IAC debt		0	0	0
Purchase of treasury stock		0	0	0
Proceeds from the exercise of stock options		0	0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0	0	0
IAC/InterActiveCorp | Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt			517,500
Repurchases of IAC debt		0	0	0
Purchase of treasury stock		0	0	0
Proceeds from the exercise of stock options		0	0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0	0	0
Match Group and ANGI Homeservices
Cash flows from financing activities:
Proceeds from the exercise of stock options		4,705	61,095	39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards		(237,564)	(264,323)	(29,830)
Match Group and ANGI Homeservices | Eliminations
Cash flows from financing activities:
Proceeds from the exercise of stock options		0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0
Match Group and ANGI Homeservices | IAC | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from the exercise of stock options		0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0	0
Match Group and ANGI Homeservices | Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from the exercise of stock options		0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards		0	0
Match Group and ANGI Homeservices | Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from the exercise of stock options		4,705	61,095
Withholding taxes paid on behalf of employees on net settled stock-based awards		(237,564)	(264,323)
Match Group
Cash flows from financing activities:
Proceeds from issuance of debt		260,000	525,000	400,000
Principal payments on debt		0	(445,172)	(450,000)
Purchase of treasury stock		(133,455)	0	0
Proceeds from the exercise of stock options				39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards				(29,830)
Purchase of Match Group stock-based awards		0	(272,459)	0
Match Group | Eliminations
Cash flows from financing activities:
Proceeds from issuance of debt		0		0
Principal payments on debt				0
Purchase of treasury stock		0
Proceeds from the exercise of stock options				0
Withholding taxes paid on behalf of employees on net settled stock-based awards				0
Match Group | IAC | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt		0	0	0
Principal payments on debt			0	0
Purchase of treasury stock		0
Proceeds from the exercise of stock options				0
Withholding taxes paid on behalf of employees on net settled stock-based awards				0
Purchase of Match Group stock-based awards			0
Match Group | Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt		0	0	0
Principal payments on debt			0	0
Purchase of treasury stock		0
Proceeds from the exercise of stock options				0
Withholding taxes paid on behalf of employees on net settled stock-based awards				0
Purchase of Match Group stock-based awards			0
Match Group | Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from issuance of debt		260,000	525,000	400,000
Principal payments on debt			(445,172)	(450,000)
Purchase of treasury stock		(133,455)
Proceeds from the exercise of stock options				39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards				(29,830)
Purchase of Match Group stock-based awards			(272,459)
ANGI Homeservices
Cash flows from financing activities:
Principal payments on debt		(13,750)	0	$ 0
Borrowing under ANGI Homeservices Term Loan			275,000
ANGI Homeservices | Eliminations
Cash flows from financing activities:
Principal payments on debt		0
ANGI Homeservices | IAC | Reportable Legal Entities
Cash flows from financing activities:
Principal payments on debt		0
Borrowing under ANGI Homeservices Term Loan			0
ANGI Homeservices | Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Principal payments on debt		0
Borrowing under ANGI Homeservices Term Loan			0
ANGI Homeservices | Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Principal payments on debt		$ (13,750)
Borrowing under ANGI Homeservices Term Loan			$ 275,000

QUARTERLY RESULTS (UNAUDITED) -

QUARTERLY RESULTS (UNAUDITED) - Summary (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Revenue	$ 1,104,103	$ 1,104,592	$ 1,059,122	$ 995,075	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 4,262,892	$ 3,307,239	$ 3,139,882
Cost of revenue	253,722	237,238	218,224	201,962	199,727	166,290	139,033	145,958	911,146	651,008	755,730
Operating income	133,920	172,832	168,437	89,950	94,360	(18,589)	75,635	37,060	565,139	188,466	(32,625)
Net earnings	217,477	171,577	280,854	87,839	23,349	225,639	80,557	28,463	757,747	358,008	(16,151)
Net earnings attributable to IAC shareholders	$ 191,752	$ 145,774	$ 218,353	$ 71,082	$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 626,961	$ 304,924	$ (41,280)
Per share information attributable to IAC shareholders:
Basic earnings per share (USD per share)	$ 2.29	$ 1.75	$ 2.61	$ 0.86	$ 0.40	$ 2.22	$ 0.84	$ 0.34	$ 7.52	$ 3.81	$ (0.52)
Diluted earnings per share (USD per share)	$ 2.04	$ 1.49	$ 2.32	$ 0.71	$ 0.37	$ 1.79	$ 0.70	$ 0.29	$ 6.59	$ 3.18	$ (0.52)
Stock-based compensation expense									$ 238,420	$ 264,618	$ 104,820
Gain (loss) on sale of equity investments			$ 133,300
Impairment of intangible assets	$ 21,300
Income tax expense (benefit)						$ 257,000			$ 3,811	(291,050)	$ (64,934)
Dictionary.com, Electus, Felix, and CityGrid | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Per share information attributable to IAC shareholders:
Gain on sale of business	92,500
HomeAdvisor
Per share information attributable to IAC shareholders:
Stock-based compensation expense	$ 14,400	$ 12,300	12,800	$ 14,600	$ 15,800	60,900
Angie's List
Per share information attributable to IAC shareholders:
After-tax costs			2,000	4,100	13,900	$ 17,400				$ 13,900
Write-off due to deferred revenue			$ 1,800	$ 2,800	$ 7,600

SUBSEQUENT EVENTS (UNAUDITED) -

SUBSEQUENT EVENTS (UNAUDITED) - Narrative (Details) - Senior Notes - Match Group Senior Notes due 2029 - Match Group - Subsequent Event $ in Millions	Feb. 15, 2019USD ($)
Subsequent Event [Line Items]
Face amount of debt instrument	$ 350
Stated interest rate (as a percent)	5.625%

SCHEDULE II - VALUATION AND Q_2

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts and revenue reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	$ 11,489	$ 16,405	$ 16,528
Charges to Earnings	48,445	28,930	17,733
Charges to Other Accounts	(573)	(1,006)	(695)
Deductions	(40,501)	(32,840)	(17,161)
Balance at end of period	18,860	11,489	16,405
Sales returns accrual
Movement in Valuation Allowances and Reserves
Balance at beginning of period	0	80	828
Charges to Earnings		0	14,998
Charges to Other Accounts		(80)	(962)
Deductions		0	(14,784)
Balance at end of period		0	80
Deferred tax valuation allowance
Movement in Valuation Allowances and Reserves
Balance at beginning of period	132,598	88,170	90,482
Charges to Earnings	(20,746)	38,144	(837)
Charges to Other Accounts	4,001	6,284	(1,475)
Deductions	0	0	0
Balance at end of period	115,853	132,598	88,170
Other reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	2,544	2,822	2,801
Balance at end of period	$ 7,734	$ 2,544	$ 2,822

Uncategorized Items - iac-20181

Label	Element	Value
Noncontrolling Interest [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 3,410,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	36,795,000
Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 36,795,000