Match (MTCH) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 02, 2018	Jun. 30, 2017
Entity Registrant Name	IAC/INTERACTIVECORP
Entity Central Index Key	891,103
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
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			$ 7,528,899,120
Common Stock
Entity Common Stock, Shares Outstanding (shares)		76,869,350
Class B Convertible Common Stock
Entity Common Stock, Shares Outstanding (shares)		5,789,499

CONSOLIDATED BALANCE SHEET

CONSOLIDATED BALANCE SHEET - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 1,630,809	$ 1,329,187
Marketable securities	4,995	89,342
Accounts receivable, net of allowance of $11,489 and $16,405, respectively	304,027	220,138
Other current assets	185,374	204,068
Total current assets	2,125,205	1,842,735
Property and equipment, net of accumulated depreciation and amortization	315,170	306,248
Goodwill	2,559,066	1,924,052
Intangible assets, net of accumulated amortization	663,737	355,451
Long-term investments	64,977	122,810
Deferred income taxes	66,321	2,511
Other non-current assets	73,334	92,066
TOTAL ASSETS	5,867,810	4,645,873
LIABILITIES:
Current portion of long-term debt	13,750	20,000
Accounts payable, trade	76,571	62,863
Deferred revenue	342,483	285,615
Accrued expenses and other current liabilities	366,924	344,910
Total current liabilities	799,728	713,388
Long-term debt, net	1,979,469	1,582,484
Income taxes payable	25,624	33,528
Deferred income taxes	35,070	228,798
Other long-term liabilities	38,229	44,178
Redeemable noncontrolling interests	42,867	32,827
Commitments and contingencies
SHAREHOLDERS' EQUITY:
Additional paid-in capital	12,165,002	11,921,559
Retained earnings	595,038	290,114
Accumulated other comprehensive loss	(103,568)	(166,123)
Treasury stock 194,163 and 193,445 shares, respectively	(10,226,721)	(10,176,600)
Total IAC shareholders' equity	2,430,028	1,869,222
Noncontrolling interests	516,795	141,448
Total shareholders' equity	2,946,823	2,010,670
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,867,810	4,645,873
Common stock $.001 par value; authorized 1,600,000 shares; issued 260,624 and 255,672 shares, respectively, and outstanding 76,829 and 72,595 shares, respectively
SHAREHOLDERS' EQUITY:
Common stock	261	256
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, 2017	Dec. 31, 2016
Accounts receivable allowance	$ 11,489	$ 16,405
Treasury stock, shares (in shares)	194,163,000	193,445,000
Common Stock
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock, authorized shares (in shares)	1,600,000,000	1,600,000,000
Common stock, issued shares (in shares)	260,624,000	255,672,000
Common stock, outstanding shares (in shares)	76,829,000	72,595,000
Class B Convertible Common Stock
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock, authorized shares (in shares)	400,000,000	400,000,000
Common stock, issued shares (in shares)	16,157,000	16,157,000
Common stock, outstanding shares (in shares)	5,789,000	5,789,000

CONSOLIDATED STATEMENT OF OPERA

CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 3,307,239	$ 3,139,882	$ 3,230,933
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	651,008	755,730	778,161
Selling and marketing expense	1,381,221	1,247,097	1,348,293
General and administrative expense	719,257	530,446	512,055
Product development expense	250,879	212,765	196,623
Depreciation	74,265	71,676	62,205
Amortization of intangibles	42,143	79,426	139,952
Goodwill impairment	0	275,367	14,056
Total operating costs and expenses	3,118,773	3,172,507	3,051,345
Operating income (loss)	188,466	(32,625)	179,588
Interest expense	(105,295)	(109,110)	(73,636)
Other (expense) income, net	(16,213)	60,650	36,938
Earnings (loss) before income taxes	66,958	(81,085)	142,890
Income tax benefit (provision)	291,050	64,934	(29,516)
Net earnings (loss)	358,008	(16,151)	113,374
Net (earnings) loss attributable to noncontrolling interests	(53,084)	(25,129)	6,098
Net earnings (loss) attributable to IAC shareholders	$ 304,924	$ (41,280)	$ 119,472
Per share information attributable to IAC shareholders:
Basic earnings (loss) per share (USD per share)	$ 3.81	$ (0.52)	$ 1.44
Diluted earnings (loss) per share (USD per share)	3.18	(0.52)	1.33
Dividends declared per share (in usd per share)	$ 0	$ 0	$ 1.36
Stock-based compensation expense by function:
Stock-based compensation expense	$ 264,618	$ 104,820	$ 105,450
Cost of revenue
Stock-based compensation expense by function:
Stock-based compensation expense	1,881	2,305	1,210
Selling and marketing expense
Stock-based compensation expense by function:
Stock-based compensation expense	31,318	6,000	10,186
General and administrative expense
Stock-based compensation expense by function:
Stock-based compensation expense	192,957	77,151	82,798
Product development expense
Stock-based compensation expense by function:
Stock-based compensation expense	$ 38,462	$ 19,364	$ 11,256

CONSOLIDATED STATEMENT OF COMPR

CONSOLIDATED STATEMENT OF COMPREHENSIVE OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 358,008	$ (16,151)	$ 113,374
Other comprehensive income (loss), net of tax:
Change in foreign currency translation adjustment	80,269	(43,126)	(68,844)
Change in unrealized gains and losses of available-for-sale securities (net of tax benefits of $3,846 and $884 in 2017 and 2016, respectively, and tax provision of $576 in 2015)	(4,026)	1,484	3,140
Total other comprehensive income (loss)	76,243	(41,642)	(65,704)
Comprehensive income (loss), net of tax	434,251	(57,793)	47,670
Components of comprehensive (income) loss attributable to noncontrolling interests:
Net (earnings) loss attributable to noncontrolling interests	(53,084)	(25,129)	6,098
Change in foreign currency translation adjustment attributable to noncontrolling interests	(13,797)	6,033	1,047
Change in unrealized gain and losses of available-for-sale securities attributable to noncontrolling interests	0	458	254
Comprehensive (income) loss attributable to noncontrolling interests	(66,881)	(18,638)	7,399
Comprehensive income (loss) attributable to IAC shareholders	$ 367,370	$ (76,431)	$ 55,069

CONSOLIDATED STATEMENT OF COMP6

CONSOLIDATED STATEMENT OF COMPREHENSIVE OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Change in unrealized gains and losses of available-for-sale securities, tax provision (benefits)	$ 3,846	$ 884	$ (576)

CONSOLIDATED STATEMENT OF SHARE

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Class B Convertible 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
Balance at beginning of period at Dec. 31, 2014	$ 1,993,142			$ 1,991,953	$ 40,427	$ 252	$ 16	$ 11,415,617	$ 325,118	$ (87,700)	$ (9,661,350)	$ 1,189
Balance at the beginning of the period (shares) at Dec. 31, 2014						252,170,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings	121,111			119,472	(7,737)				119,472			1,639
Other comprehensive income (loss), net of tax	(64,403)			(64,403)	(1,301)					(64,403)
Stock-based compensation expense	92,493			87,685	6,725			87,685				4,808
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(37,731)			(37,731)		$ 2		(37,733)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)						1,845,000
Income tax benefit related to stock-based awards	44,577			44,577				44,577
Dividends	(113,196)			(113,196)					(113,196)
Purchase of treasury stock	(200,000)	$ (200,000)		(200,000)							(200,000)
Adjustment of redeemable noncontrolling interests to fair value	0				(32,207)
Adjustment of redeemable noncontrolling interests to fair value	(23,155)			(23,155)	23,155			(23,155)
Noncontrolling interests related to Match Group IPO, net of fees and expenses	428,283											428,283
Purchase of Match Group stock-based awards	(23,431)											(23,431)
Transfer from noncontrolling interests to redeemable noncontrolling interests	(1,189)				1,189							(1,189)
Other	(676)			(676)	140			(676)
Balance at end of period at Dec. 31, 2015	2,215,825			1,804,526	30,391	$ 254	$ 16	11,486,315	331,394	(152,103)	(9,861,350)	411,299
Balance at the end of the period (shares) at Dec. 31, 2015						254,015,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Common stock, par value (USD per share)						$ 10	$ 10
Net (loss) earnings	(12,302)			(41,280)	(3,849)				(41,280)			28,978
Other comprehensive income (loss), net of tax	(42,027)			(35,151)	385					(35,151)		(6,876)
Stock-based compensation expense	94,724			50,201	1,632			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)	7,921			(7,560)
Other	(3,422)			(3,069)	(1,124)			(3,069)				(353)
Purchase of redeemable noncontrolling interests	0				(2,529)
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)	0	$ 0	$ 0	(7,691)	0	0	0	7,691
Changes in noncontrolling interests of Match Group due to the issuance of its common stock (shares)						0	0
Noncontrolling interests created in an acquisition	22,033			12,222				12,222				9,811
Balance at end of period at Dec. 31, 2016	2,010,670			1,869,222	32,827	$ 256	$ 16	11,921,559	290,114	(166,123)	(10,176,600)	141,448
Balance at the end of the period (shares) at Dec. 31, 2016						255,672,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Common stock, par value (USD per share)		$ 0.001	$ 0.001			$ 10	$ 10
Net (loss) earnings	354,388			304,924	3,620				304,924			49,464
Other comprehensive income (loss), net of tax	74,952			62,446	1,291					62,446		12,506
Stock-based compensation expense	246,388			66,333	2,017			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					(14,641)
Adjustment of redeemable noncontrolling interests to fair value	(6,341)			(6,341)	6,341			(6,341)
Other	1,027			148	(6,346)			148				879
Purchase of noncontrolling interests	(848)											(848)
Issuance of Match Group common stock pursuant to stock-based awards, net of withholding taxes	(464,209)			(460,774)				(460,890)		116		(3,435)
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 ANGI Homeservices common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests in ANGI Homeservices	(8,493)			(11,223)				(11,216)		(7)		2,730
Purchase of exchangeable note hedge	(74,365)			(74,365)				(74,365)
Equity component of Exchangeable Notes, net of deferred financing costs and deferred tax asset	71,158			71,158				71,158
Issuance of warrants	23,650			23,650				23,650
Balance at end of period at Dec. 31, 2017	$ 2,946,823			$ 2,430,028	$ 42,867	$ 261	$ 16	$ 12,165,002	$ 595,038	$ (103,568)	$ (10,226,721)	$ 516,795
Balance at the end of the period (shares) at Dec. 31, 2017						260,624,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Common stock, par value (USD per share)		$ 0.001	$ 0.001			$ 10	$ 10

CONSOLIDATED STATEMENT OF CASH

CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net earnings (loss)	$ 358,008	$ (16,151)	$ 113,374
Adjustments to reconcile net earnings (loss) to net cash provided by operating activities:
Stock-based compensation expense	264,618	104,820	105,450
Depreciation	74,265	71,676	62,205
Amortization of intangibles	42,143	79,426	139,952
Goodwill impairment	0	275,367	14,056
Deferred income taxes	(285,278)	(119,181)	(59,786)
Acquisition-related contingent consideration fair value adjustments	5,801	2,555	(15,461)
Gain from the sale of businesses and investments, net	(32,673)	(50,965)	(1,005)
Impairment of long-term investments	12,214	10,680	6,689
Acquisition-related contingent consideration payment	(11,140)	0	0
Bad debt expense	28,930	17,733	16,648
Gain on real estate transaction	0	0	(34,341)
Other adjustments, net	43,633	(12,639)	8,907
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Accounts receivable	(115,169)	1,283	(29,680)
Other assets	5,671	(12,905)	(21,174)
Accounts payable and other current liabilities	(14,142)	(52,359)	8,756
Income taxes payable and receivable	655	8,998	24,167
Deferred revenue	39,154	35,803	66,914
Net cash provided by operating activities	416,690	344,141	405,671
Cash flows from investing activities:
Acquisitions, net of cash acquired	(149,094)	(18,403)	(617,402)
Capital expenditures	(75,523)	(78,039)	(62,049)
Investments in time deposits	0	(87,500)	0
Proceeds from maturities of time deposits	0	87,500	0
Proceeds from maturities and sales of marketable debt securities	114,350	252,369	218,462
Purchases of marketable debt securities	(29,891)	(313,943)	(93,134)
Purchases of investments	(9,106)	(12,565)	(34,470)
Net proceeds from the sale of businesses and investments	185,778	172,228	9,413
Other, net	2,994	11,215	(3,541)
Net cash provided by (used in) investing activities	39,508	12,862	(582,721)
Cash flows from financing activities:
Proceeds from issuance of IAC debt	517,500	0	0
Principal payments on IAC debt	(393,464)	(126,409)	(80,000)
Proceeds from issuance of Match Group debt	525,000	400,000	788,000
Principal payments on Match Group debt	(445,172)	(450,000)	0
Borrowing under ANGI Homeservices Term Loan	275,000	0	0
Purchase of exchangeable note hedge	(74,365)	0	0
Proceeds from issuance of warrants	23,650	0	0
Debt issuance costs	(33,744)	(7,811)	(19,050)
Fees and expenses related to note exchange	0	0	(6,954)
Proceeds from Match Group initial public offering, net of fees and expenses	0	0	428,789
Purchase of IAC treasury stock	(56,424)	(308,948)	(200,000)
Dividends	0		(113,196)
Withholding taxes paid on behalf of employees on net settled stock-based awards			(65,743)
Purchase of Match Group stock-based awards	(272,459)	0	(23,431)
Purchase of noncontrolling interests	(15,439)	(2,740)	(32,207)
Acquisition-related contingent consideration payments	(27,289)	(2,180)	(5,750)
Funds returned from (held in) escrow for MyHammer tender offer	10,604	(10,548)	0
Decrease (increase) in restricted cash related to bond redemptions	20,141	(141)	(20,000)
Other, net	(5,000)	(2,705)	607
Net cash (used in) provided by financing activities	(166,124)	(502,829)	678,390
Total cash provided (used)	290,074	(145,826)	501,340
Effect of exchange rate changes on cash and cash equivalents	11,548	(6,434)	(10,298)
Net increase (decrease) in cash and cash equivalents	301,622	(152,260)	491,042
Cash and cash equivalents at beginning of period	1,329,187	1,481,447	990,405
Cash and cash equivalents at end of period	1,630,809	1,329,187	1,481,447
IAC
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Net cash provided by operating activities	(61,002)
Cash flows from investing activities:
Acquisitions, net of cash acquired	0
Capital expenditures	(337)
Proceeds from maturities and sales of marketable debt securities	114,350
Purchases of marketable debt securities	(29,891)
Purchases of investments	0
Net proceeds from the sale of businesses and investments	1,266
Other, net	0
Net cash provided by (used in) investing activities	85,388
Cash flows from financing activities:
Proceeds from issuance of IAC debt	0
Principal payments on IAC debt	(393,464)
Proceeds from issuance of Match Group debt	0
Principal payments on Match Group debt	0
Borrowing under ANGI Homeservices Term Loan	0
Purchase of exchangeable note hedge	0
Proceeds from issuance of warrants	23,650
Debt issuance costs	0
Purchase of IAC treasury stock	(56,424)
Purchase of Match Group stock-based awards	0
Purchase of noncontrolling interests	0
Acquisition-related contingent consideration payments	0
Funds returned from (held in) escrow for MyHammer tender offer	0
Decrease (increase) in restricted cash related to bond redemptions	20,141
Other, net	251
Net cash (used in) provided by financing activities	7,535
Total cash provided (used)	31,921
Effect of exchange rate changes on cash and cash equivalents	75
Net increase (decrease) in cash and cash equivalents	31,996
Cash and cash equivalents at beginning of period	553,643
Cash and cash equivalents at end of period	585,639	553,643
Non-Guarantor Subsidiaries
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Net cash provided by operating activities	346,111
Cash flows from investing activities:
Acquisitions, net of cash acquired	(146,544)
Capital expenditures	(74,136)
Proceeds from maturities and sales of marketable debt securities	0
Purchases of marketable debt securities	0
Purchases of investments	(9,106)
Net proceeds from the sale of businesses and investments	184,512
Other, net	1,050
Net cash provided by (used in) investing activities	(44,224)
Cash flows from financing activities:
Proceeds from issuance of IAC debt	517,500
Principal payments on IAC debt	0
Proceeds from issuance of Match Group debt	525,000
Principal payments on Match Group debt	(445,172)
Borrowing under ANGI Homeservices Term Loan	275,000
Purchase of exchangeable note hedge	(74,365)
Proceeds from issuance of warrants	0
Debt issuance costs	(33,744)
Purchase of IAC treasury stock	0
Purchase of Match Group stock-based awards	(272,459)
Purchase of noncontrolling interests	(15,439)
Acquisition-related contingent consideration payments	(27,289)
Funds returned from (held in) escrow for MyHammer tender offer	10,604
Decrease (increase) in restricted cash related to bond redemptions	0
Other, net	(5,251)
Net cash (used in) provided by financing activities	(43,734)
Total cash provided (used)	258,153
Effect of exchange rate changes on cash and cash equivalents	11,473
Net increase (decrease) in cash and cash equivalents	269,626
Cash and cash equivalents at beginning of period	775,544
Cash and cash equivalents at end of period	1,045,170	775,544
IAC/InterActiveCorp
Cash flows from financing activities:
Proceeds from the exercise of stock options	82,397	25,821	27,325
Withholding taxes paid on behalf of employees on net settled stock-based awards	(93,832)	(26,716)
IAC/InterActiveCorp | IAC
Cash flows from financing activities:
Proceeds from the exercise of stock options	82,397	25,821	27,325
Withholding taxes paid on behalf of employees on net settled stock-based awards	(93,832)	(26,716)	(65,743)
IAC/InterActiveCorp | Non-Guarantor Subsidiaries
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
Cash flows from financing activities:
Proceeds from the exercise of stock options	59,442	39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards	(254,210)	(29,830)
Match Group | IAC
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 | Non-Guarantor Subsidiaries
Cash flows from financing activities:
Proceeds from the exercise of stock options	59,442	39,378	0
Withholding taxes paid on behalf of employees on net settled stock-based awards	(254,210)	(29,830)	0
ANGI Homeservices
Cash flows from financing activities:
Proceeds from the exercise of stock options	1,653
Withholding taxes paid on behalf of employees on net settled stock-based awards	(10,113)
ANGI Homeservices | IAC
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
ANGI Homeservices | Non-Guarantor Subsidiaries
Cash flows from financing activities:
Proceeds from the exercise of stock options	1,653	0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards	$ (10,113)	$ 0	$ 0

ORGANIZATION

ORGANIZATION	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	ORGANIZATION IAC is a leading media and Internet company composed of widely known consumer brands, such as Match, Tinder, PlentyOfFish and OkCupid, which are part of Match Group's online dating portfolio, HomeAdvisor and Angie's List, which are operated by ANGI Homeservices, as well as Vimeo, Dotdash, Dictionary.com, The Daily Beast and Investopedia. All references to "IAC," the "Company," "we," "our" or "us" in this report are to IAC/InterActiveCorp. The Company has six reportable segments, which are described below. Match Group Our Match Group segment consists of the businesses and operations of Match Group, Inc. (“Match Group”). Match Group completed its initial public offering ("IPO") on November 24, 2015. As of December 31, 2017 , IAC’s economic and voting interest in Match Group were 81.2% and 97.6% , respectively. Through Match Group, we operate a dating business that consists of a portfolio of brands, available in 42 languages across more than 190 countries, including the following key brands: Tinder, Match, PlentyOfFish, Meetic, OkCupid, OurTime, Pairs as well as a number of other brands. Through the portfolio of brands within Match Group, we are a leading provider of subscription dating products servicing North America, Western Europe, Asia and many other regions around the world. We provide these services through websites and applications that we own and operate. ANGI Homeservices Our ANGI Homeservices segment includes the North America and European businesses of ANGI Homeservices Inc. On September 29, 2017, the Company completed the combination (the "Combination") of the businesses in the Company's HomeAdvisor segment and Angie's List, Inc. ("Angie's List") under a new publicly traded company called ANGI Homeservices. As of December 31, 2017 , IAC’s economic and voting interest in ANGI Homeservices were 86.9% and 98.5% , respectively. In connection with the transaction, the Company changed the name of the HomeAdvisor segment to ANGI Homeservices and year-over-year comparisons for financial results for this segment are to the historical results of the HomeAdvisor segment (adjusted to reflect corporate allocations from IAC). ANGI Homeservices is the world's largest digital marketplace for home services, connecting millions of homeowners across the globe with home service professionals. ANGI Homeservices operates leading brands in eight countries, including HomeAdvisor® and Angie's List® (United States), HomeStars (Canada), Travaux.com (France), MyHammer (Germany and Austria), MyBuilder (UK), Werkspot (Netherlands) and Instapro (Italy). HomeAdvisor acquired controlling interests in MyBuilder Limited ("MyBuilder") on March 24, 2017, and HomeStars Inc. ("HomeStars") on February 8, 2017, leading home services platforms in the United Kingdom and Canada, respectively. Video Our Video segment consists of Vimeo, Electus, IAC Films and Daily Burn. Vimeo operates a global video sharing platform for creators and their audiences. We provide creators with professional tools to host, manage, review, distribute and monetize videos online, while offering audiences a high quality, ad-free viewing experience across devices. On October 18, 2017, Vimeo acquired Livestream, a leading live video solution that powers millions of events a year. Electus provides production and producer services for both unscripted and scripted television and digital content, primarily for initial sale and distribution in the United States and internationally. Our content is distributed on a wide range of platforms, including broadcast television, premium and basic cable television, subscription-based and ad-supported video-on-demand services and other outlets. Electus also operates Electus Digital, which consists of the following websites and properties: CollegeHumor.com, Dorkly.com and Drawfee.com; YouTube channels WatchLOUD, Nuevon and Hungry; and Big Breakfast (a production company). Through Electus, we also operate Notional. IAC Films provides production and producer services for feature films, primarily for initial sale and distribution in the United States and internationally. Our content is distributed through theatrical releases and video-on-demand services. 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. Applications Our Applications segment includes Consumer, which develops and distributes downloadable desktop and mobile applications, including Apalon, which houses our mobile applications operations, and SlimWare, which houses our downloadable desktop software and service operations; and Partnerships, which includes our business-to-business partnership operations. Through our Consumer business, we develop, market and distribute a variety of applications, primarily browser extensions, which consist of a browser tab page and related technology that together enable users to run search queries directly from their web browsers. Apalon is a mobile development company with one of the largest and most popular portfolios of mobile applications worldwide. SlimWare is a provider of community-powered software and services that clean, repair, update, secure and optimize computers, mobile phones and digital devices. Through our Partnerships business, we work closely with partners in the software, media and other industries to design and develop customized browser-based search applications to be bundled and distributed with these partners’ products and services. Publishing The Publishing segment includes our Premium Brands business, which is composed of Dotdash, Dictionary.com, Investopedia and The Daily Beast; and our Ask & Other business, which primarily includes Ask Media Group, CityGrid and, for periods prior to its sale on June 30, 2016, ASKfm. Premium Brands Our Premium Brands business primarily consists of the following destination websites: • Dotdash, a network of digital brands providing reliable information and inspiration in select vertical categories, including The Spruce (home), The Balance (money), Verywell (health), Lifewire (tech), TripSavvy (travel) and ThoughtCo (lifelong learning); • Dictionary.com, which primarily provides online and mobile dictionary, thesaurus and reference services; • Investopedia, a resource for investment and personal finance education and information, as well as online courses through Investopedia Academy for a fee; and • The Daily Beast, a website dedicated to news, commentary, culture and entertainment that curates and publishes existing and original online content from its own roster of contributors in the United States. Ask & Other Our Ask & Other business primarily includes: • Ask Media Group, a collection of websites providing general search services and information; • CityGrid, an advertising network that integrates local content and advertising for distribution to affiliated and third party publishers across web and mobile platforms; and • For periods prior to its sale on June 30, 2016, ASKfm, a questions and answers social network. Other The Other segment consists of the results of The Princeton Review, ShoeBuy and PriceRunner for periods prior to the sales of these businesses, which occurred on March 31, 2017, December 30, 2016 and March 18, 2016, respectively. The Princeton Review provided a variety of educational test preparation, academic tutoring and college counseling services; ShoeBuy was an Internet retailer of footwear and related apparel and accessories; and PriceRunner was a shopping comparison website.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES 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 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. 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. Investments in the common stock or in-substance common stock of entities in which the Company does not have the ability to exercise significant influence over the operating and financial matters of the investee are accounted for using the cost method. Investments in companies that IAC does not control, which are not in the form of common stock or in-substance common stock, are also accounted for using the cost method. The Company evaluates each cost and equity method investment for impairment on a quarterly basis and recognizes an impairment loss if a decline in value is determined to be other-than-temporary. Such impairment evaluations include, but are not limited to: the current business environment, including competition; going concern considerations such as financial condition, the rate at which the investee utilizes cash and the investee's ability to obtain additional financing to achieve its business plan; the need for changes to the investee's existing business model due to changing business and regulatory environments and its ability to successfully implement necessary changes; and comparable valuations. If the Company has not identified events or changes in circumstances that may have a significant adverse effect on the fair value of a cost method investment, then the fair value of such cost method investment is not estimated, as it is impracticable to do so. 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 securities and long-term investments; 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; the liabilities for uncertain tax positions; 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 recognizes revenue when persuasive evidence of an arrangement exists, services are rendered or merchandise is delivered to customers, the fee or price charged is fixed or determinable and collectability is reasonably assured. Deferred revenue is recorded when payments are received, or contractually due, in advance of the Company's rendering of services, availability of media content (films, television, or digital content) for broadcast or exhibition or delivery of merchandise. Match Group Match Group's 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 using a credit card or through mobile app stores, and, subject to certain conditions identified in our terms and conditions, all purchases are final and nonrefundable. Fees collected, or contractually due, in advance for subscriptions are deferred and recognized using the straight-line method over the terms of the applicable subscription period, which primarily range from one to six months, and corresponding mobile app store fees incurred on such transactions, if any, are deferred and expensed over the same period. Deferred revenue at Match Group is $198.3 million and $161.1 million at December 31, 2017 and 2016 , respectively. Revenue is also earned from online advertising, the purchase of à la carte features and offline events. Online advertising revenue is recognized every time an advertisement is displayed. Revenue from the purchase of à la carte features is recognized based on usage. Revenue and the related expenses associated with offline events are recognized when each event occurs. ANGI Homeservices ANGI Homeservices revenue is primarily derived from (i) consumer connection revenue, which comprises fees paid by service professionals for consumer matches (regardless of whether the professional ultimately provides the requested service), and (ii) membership subscriptions fees paid by service professionals. Consumer connection revenue varies based upon certain factors including the service requested, type of match (such as Instant Booking, Instant Connect, same day service or next day service) and geographic location of service. Effective with the Combination, revenue is also derived from Angie's List (i) sales of time-based advertising to service professionals and (ii) membership subscription fees from consumers. ANGI Homeservices consumer connection revenue is generated and recognized when an in‑network service professional is delivered a consumer match. Membership subscription revenue is generated through subscription sales to service professionals and is deferred and recognized over the term of the applicable membership. Membership agreements can be one month, three months , or one year. 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. These contracts include an early termination penalty. Angie's List revenue from the sale of website, mobile and call center advertising is recognized ratably over the period during which the advertisements run. Revenue from the sale of advertising in the Angie’s List Magazine is recognized in the period in which the publication is published and distributed. Angie's List prepaid consumer membership subscription fees are recognized as revenue ratably over the term of the associated subscription, which is typically one year. Deferred revenue at ANGI Homeservices is $64.1 million and $18.8 million at December 31, 2017 and 2016 , respectively. The balance at December 31, 2017 includes Angie's List deferred revenue of $37.7 million . Video Revenue of businesses included in this segment is generated primarily through subscriptions, media production and distribution, and advertising. Production revenue is recognized when the production is available for the customer to broadcast or exhibit, subscription fee revenue is recognized over the terms of the applicable subscriptions, which are one month or one year, and advertising revenue is recognized when an ad is displayed or over the period earned. Deferred revenue at Vimeo is $49.4 million and $36.7 million at December 31, 2017 and 2016 , respectively. Deferred revenue at Electus totals $12.8 million and $23.1 million at December 31, 2017 and 2016 , respectively. Applications Substantially all of Applications' revenue 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 Applications businesses are supplied to us by Google Inc. ("Google") pursuant to our services agreement with Google. Pursuant to this agreement, those of our Applications 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 Applications 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. We recognize 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 significantly lesser extent, Applications' revenue also consists of fees related to subscription downloadable applications, which are recognized over the terms of the applicable subscriptions, primarily one to two years, and fees related to paid mobile downloadable applications and display advertisements, which are recognized at the time of the sale and when the ad is displayed, respectively. Deferred revenue at Applications is $23.6 million and $26.1 million at December 31, 2017 and 2016 , respectively. Publishing Publishing's revenue consists principally of advertising revenue, which is generated primarily through the display of paid listings in response to search queries, display advertisements (sold directly and through programmatic ad sales) and fees related to paid mobile downloadable applications. The substantial majority of the paid listings that our Publishing businesses display are supplied to us by Google in the manner and pursuant to the services agreement with Google, which is described above under " Applications. " Other The Princeton Review's revenue consisted primarily of fees received directly from students for in-person and online test preparation classes, access to online test preparation materials and individual tutoring services. Fees from classes and access to online materials were recognized over the period of the course and the period of the online access, respectively. Tutoring fees were recognized based on usage. ShoeBuy's revenue consisted of merchandise sales, reduced by incentive discounts and sales returns, and was recognized when delivery to the customer had occurred. Delivery was considered to have occurred when the customer took title and assumed the risks and rewards of ownership, which was on the date of shipment. Accruals for returned merchandise were based on historical experience. Shipping and handling fees billed to customers was recorded as revenue. The costs associated with shipping goods to customers were recorded as cost of revenue. PriceRunner's revenue consisted principally of advertising revenue that, depending on the terms of the arrangement, was recognized when a user clicked on an ad, or when a user clicked-through on the ad and took a specified action on the destination site. 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, commercial paper rated A1/P1 or better and treasury discount notes. Internationally, cash equivalents primarily consist of AAA rated government money market funds and time deposits. Marketable Securities At December 31, 2017 , marketable securities consist of commercial paper rated A1+/P1. 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. The Company also invests in marketable equity securities as part of its investment strategy. All marketable securities are classified as available-for-sale and are reported at fair value. The unrealized gains and losses on marketable securities, net of tax, are included in accumulated other comprehensive income as a separate component of shareholders' equity. The specific-identification method is used to determine the cost of securities sold and the amount of unrealized gains and losses reclassified out of accumulated other comprehensive income into earnings. The Company employs a methodology that considers available evidence in evaluating potential other-than-temporary impairments of its investments. Investments are considered to be impaired when a decline in fair value below the amortized cost basis is determined to be other-than-temporary. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the amortized cost basis, the financial condition and near-term prospects of the issuer, and whether it is not more likely than not that the Company will be required to sell the security before the recovery of the amortized cost basis, which may be maturity. If a decline in fair value is determined to be other-than-temporary, an impairment charge is recorded in current earnings and a new cost basis in the investment is established. 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. For the years ended December 31, 2017 , 2016 and 2015 , revenue from Google represents 22% , 26% and 40% respectively, of the Company's consolidated revenue. The services agreement became effective on April 1, 2016, following the expiration of the previous services agreement, and expires on March 31, 2020; however, the Company may choose to terminate the agreement effective March 31, 2019. 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. For the years ended December 31, 2017 , 2016 and 2015 , revenue earned from Google was $740.7 million , $824.4 million and $1.3 billion , respectively. This revenue is earned by the businesses comprising the Applications and Publishing segments. For the years ended December 31, 2017 , 2016 and 2015 , revenue earned from Google represents 83% , 87% and 94% of Applications revenue and 71% , 73% and 83% of Publishing revenue, respectively. Accounts receivable related to revenue earned from Google totaled $72.4 million and $65.8 million at December 31, 2017 and 2016 , respectively. 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. Accounts Receivable, net of allowance for doubtful accounts and revenue reserves Accounts receivable are stated at amounts due from customers, net of an allowance for doubtful accounts and revenue reserves. Accounts receivable outstanding longer than the contractual payment terms are considered past due. The Company determines its allowance by considering a number of factors, including the length of time accounts receivable are past due, the Company's previous loss history, the specific customer's ability to pay its obligation to the Company and the condition of the general economy and the customer's industry. The Company writes off accounts receivable when they become uncollectible. The Company also maintains allowances to reserve for potential credits issued to customers or other revenue adjustments. The amounts of these reserves are based, in part, on historical experience. 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 $46.4 million and $46.9 million at December 31, 2017 and 2016 , 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 detailed 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 are 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 8—Fair Value Measurements and 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 loss equal to the excess is recorded. For the Company's annual goodwill test at October 1, 2017, a qualitative assessment of the Match Group, ANGI Homeservices, Vimeo and Applications 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 is described below: • Match Group's October 1, 2017 market capitalization of $6.3 billion exceeded its carrying value by more than 1100% and Match Group's strong operating performance. • ANGI Homeservices' October 1, 2017 market capitalization of $5.9 billion exceeded its carrying value by more than 450% and ANGI Homeservices' strong operating performance. • The Company performed valuations of the Vimeo and Applications reporting units during 2017. 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, 2017. The fair value of each of these businesses was in excess of its October 1, 2017 carrying value. For the Company's annual goodwill test at October 1, 2017, the Company quantitatively tested the Daily Burn and Electus reporting units. The Company's quantitative test indicated that the fair value of each of these reporting units is in excess of its respective carrying value; therefore, the goodwill of these reporting units is not impaired. The Company's Publishing reporting unit has no goodwill. The aggregate goodwill balance for the reporting units for which the most recent estimate of fair value is less than 120% of their carrying values is approximately $450 million . The fair value of the Company's reporting units 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 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 determining the fair value of the Company's reporting units ranged from 12.5% to 17.5% in 2017 and 10% to 17.5% in 2016. 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. In 2017, the Company did not quantitatively assess the Angie's List indefinite-lived intangible assets acquired through the Combination given the proximity of the September 29, 2017 transaction date to the October 1, 2017 annual test date. The Company determines the fair values of its indefinite-lived intangible assets using avoided royalty DCF analyses. Significant judgments inherent in these analyses 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 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 11% to 16% in both 2017 and 2016, and the royalty rates used ranged from 2% and 7% in both 2017 and 2016. The 2017 annual assessment 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 impairment charges related to the entire $275.4 million balance of the Publishing reporting unit goodwill and $11.6 million related to certain Publishing indefinite-lived intangible assets. The goodwill impairment charge at Publishing was driven by the impact from the new 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 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 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 Publishing reporting unit. To determine a peer group of companies for 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 charge 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. In 2015, the Company identified and recorded impairment charges of $88.0 million related to certain indefinite-lived intangible assets at the Publishing segment and $14.1 million at the Other segment related to goodwill at ShoeBuy. The indefinite-lived intangible asset impairment charge at Publishing related to certain trade names of certain Ask & Other direct marketing brands, including Ask Media Group. The impairment charge reflected the impact of Google ecosystem changes that impacted our ability to market, the effect of the reduced revenue share on mobile under the terms of the services agreement with Google, and the shift in focus to higher margin businesses in Publishing's Premium Brands. The combined impact of these factors reduced the forecasted revenue and profits for these brands and the impairment charge reflected the resultant reduction in fair value. The goodwill impairment charge at ShoeBuy was due to increased investment and the seasonal effect of high inventory levels as of October 1, 2015. The Company's reporting units are consistent with its determination of its operating segments. Goodwill is tested for impairment at the reporting unit level. See " Note 14—Segment Information " for additional information regarding the Company's method of determining operating and reportable segments. 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 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 prices for identical assets and liabilities in active markets. • Level 2: Other inputs, which are observable directly or indirectly, such as quoted prices for similar assets or liabilities in active markets, quoted 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 ma

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 (In thousands) U.S. $ (52,606 ) $ (248,433 ) $ 79,656 Foreign 119,564 167,348 63,234 Total $ 66,958 $ (81,085 ) $ 142,890 The components of the (benefit) provision for income taxes are as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Current income tax (benefit) provision: Federal $ (31,844 ) $ 23,343 $ 67,505 State 1,964 3,662 7,785 Foreign 24,108 27,242 14,012 Current income tax (benefit) provision (5,772 ) 54,247 89,302 Deferred income tax (benefit) provision: Federal (255,477 ) (100,798 ) (50,254 ) State (28,364 ) (9,518 ) (3,727 ) Foreign (1,437 ) (8,865 ) (5,805 ) Deferred income tax (benefit) provision (285,278 ) (119,181 ) (59,786 ) Income tax (benefit) provision $ (291,050 ) $ (64,934 ) $ 29,516 The deferred tax asset for net operating losses ("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 and $56.4 million for the years ended December 31, 2016 and 2015 , respectively, for excess tax deductions attributable to stock-based compensation. For the years ended December 31, 2016 and 2015 , 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, 2017 and 2016 : December 31, 2017 2016 (In thousands) Income taxes receivable (payable): Other current assets $ 33,239 $ 41,352 Other non-current assets 1,949 1,615 Accrued expenses and other current liabilities (11,798 ) (5,788 ) Income taxes payable (25,624 ) (33,528 ) Net income taxes (payable) receivable $ (2,234 ) $ 3,651 Deferred tax assets (liabilities): Other non-current assets $ 66,321 $ 2,511 Deferred income taxes (35,070 ) (228,798 ) Net deferred tax assets (liabilities) $ 31,251 $ (226,287 ) 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, 2017 2016 (In thousands) Deferred tax assets: Accrued expenses $ 22,234 $ 40,273 NOL carryforwards 292,812 63,948 Tax credit carryforwards 78,715 11,570 Stock-based compensation 77,976 87,914 Equity method investments 12,066 17,455 Intangible and other assets — 13,708 Other 30,265 30,044 Total deferred tax assets 514,068 264,912 Less valuation allowance (132,598 ) (88,170 ) Net deferred tax assets 381,470 176,742 Deferred tax liabilities: Investment in subsidiaries (247,167 ) (385,474 ) Intangible and other assets (87,811 ) — Other (15,241 ) (17,555 ) Total deferred tax liabilities (350,219 ) (403,029 ) Net deferred tax assets (liabilities) $ 31,251 $ (226,287 ) At December 31, 2017 , the Company has federal and state NOLs of $850.2 million and $859.4 million , respectively. The federal NOLs, if not utilized, will expire at various times between 2023 and 2037, and the state NOLs, if not utilized, will expire at various times between 2018 and 2037. Federal and state NOLs of $586.8 million and $496.0 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, 2017 , the Company has foreign NOLs of $378.2 million available to offset future income. Of these foreign NOLs, $355.4 million can be carried forward indefinitely and $22.8 million will expire at various times between 2018 and 2037. During 2017 , the Company recognized tax benefits related to NOLs of $257.7 million . Included in this amount is $79.2 million of tax benefits of acquired attributes which was recorded as a reduction in goodwill. At December 31, 2017 , the Company has federal and state capital losses of $11.3 million and $30.9 million , respectively. If not utilized, the capital losses will expire between 2020 and 2021. Utilization of capital losses will be limited to the Company's ability to generate future capital gains. At December 31, 2017 , the Company has tax credit carryforwards of $87.6 million . Of this amount, $49.3 million relates to credits for foreign taxes, of which $41.8 million was generated from the provisional Transition Tax calculation (described below), $31.1 million relates to credits for research activities and $7.2 million relates to various other credits. Of these credit carryforwards, $15.2 million can be carried forward indefinitely and $72.4 million will expire between 2018 and 2037. 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. As of December 31, 2017 , the Company has a gross deferred tax asset of $130.0 million that the Company expects to fully utilize on a more likely than not basis. During 2017 , the Company's valuation allowance increased by $44.4 million primarily due to the establishment of foreign NOLs related to a recent acquisition. At December 31, 2017 , the Company has a valuation allowance of $132.6 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 (benefit) provision 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, 2017 2016 2015 (In thousands) Income tax (benefit) provision at the federal statutory rate of 35% $ 23,435 $ (28,446 ) $ 50,006 Transition tax 62,667 — — Stock-based compensation (358,901 ) 3,998 1,787 Foreign income taxed at a different statutory tax rate (14,725 ) (27,115 ) (10,382 ) State income taxes, net of effect of federal tax benefit 86 (3,880 ) 2,208 Realization of certain deferred tax assets (3,133 ) — (22,440 ) Non-taxable sale and non-deductible goodwill associated with ShoeBuy — (13,142 ) 4,920 Goodwill impairment of Publishing — 10,649 — Research credit (5,304 ) (2,231 ) (2,354 ) Non-deductible impairments for certain cost method investments 2,669 3,489 2,341 Deferred tax adjustment for enacted changes in tax laws and rates 705 (4,594 ) — Other, net 1,451 (3,662 ) 3,430 Income tax (benefit) provision $ (291,050 ) $ (64,934 ) $ 29,516 A reconciliation of the beginning and ending amount of unrecognized tax benefits, including penalties but excluding interest, is as follows: December 31, 2017 2016 2015 (In thousands) Balance at January 1 $ 38,372 $ 40,808 $ 30,386 Additions based on tax positions related to the current year 2,050 2,033 4,227 Additions for tax positions of prior years 1,994 2,676 14,467 Reductions for tax positions of prior years (3,761 ) (743 ) (1,556 ) Settlements — (5,107 ) — Expiration of applicable statutes of limitations (1,923 ) (1,295 ) (6,716 ) Balance at December 31 $ 36,732 $ 38,372 $ 40,808 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, 2017 , 2016 and 2015 is a $0.1 million benefit, $0.4 million expense and $0.1 million expense, respectively, net of related deferred taxes of less than $0.1 million , $0.2 million and less than $0.1 million , respectively, for interest on unrecognized tax benefits. At December 31, 2017 and 2016 , the Company has accrued $3.0 million and $2.6 million , respectively, for the payment of interest. At both December 31, 2017 and 2016 , the Company has accrued $1.7 million 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 is currently auditing the Company’s federal income tax returns for the years ended December 31, 2010 through 2012. The statute of limitations for the years 2010 through 2012 has been extended to June 30, 2019, and the statute of limitations for the year 2013 has been extended to June 30, 2018. Various other jurisdictions are open to examination for tax years beginning with 2009. Income taxes payable include reserves 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 require periodic adjustments and which may not accurately anticipate actual outcomes. Although management currently believes changes to reserves 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, 2017 and 2016 , unrecognized tax benefits, including interest and penalties, were $39.7 million and $41.0 million , respectively. If unrecognized tax benefits at December 31, 2017 are subsequently recognized, $37.2 million , net of related deferred tax assets and interest, would reduce income tax expense. The comparable amount as of December 31, 2016 was $37.7 million . The Company believes that it is reasonably possible that its unrecognized tax benefits could decrease by $13.2 million by December 31, 2018, due to expirations of statutes of limitations; $12.9 million of which would reduce the income tax provision. On December 22, 2017, the U.S. enacted the Tax Act. The Tax Act subjects to U.S. taxation certain previously deferred earnings of foreign subsidiaries as of December 31, 2017 (“Transition Tax”) and implements a number of changes that take 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’s income tax provision for the year ended December 31, 2017 includes an expense of $63.8 million related to the Tax Act, of which, $62.7 million relates to the Transition Tax and $1.1 million relates to the remeasurement of U.S. net deferred tax assets due to the reduction in the corporate income tax rate. The Company has sufficient current year NOLs to offset the taxable income resulting from the Transition Tax and, therefore, will not be required to pay the one-time Transition Tax. The Transition Tax on deemed repatriated foreign earnings is a tax on previously untaxed accumulated and current earnings and profits ("E&P") of the Company's foreign subsidiaries. To determine the amount of the Transition Tax, the Company must determine, among other factors, the amount of post-1986 E&P of its foreign subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. The Company was able to make a reasonable estimate of the Transition Tax and has recorded a provisional Transition Tax expense of $62.7 million . Any adjustment of the Company's provisional tax expense will be reflected as a change in estimate in its results in the period in which the change in estimate is made in accordance with Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act . The Company is continuing to gather additional information to more precisely compute the amount of the Transition Tax and expects to finalize its calculation prior to the filing of its U.S. federal tax return, which is due on October 15, 2018. The additional information includes, but is not limited to, the allocation and sourcing of income and deductions in 2017 for purposes of calculating the utilization of foreign tax credits. In addition, our estimates may also be impacted and adjusted as the law is clarified and additional guidance is issued at the federal and state levels. As of December 31, 2017 , the Company has $452.2 million in foreign cash of which approximately $420.2 million can be repatriated without any significant tax consequences as it has been substantially subjected to U.S. income tax under the Transition Tax imposed by the Tax Act. The Company has not provided for approximately $7.9 million of deferred taxes for the $101.2 million of the foreign cash earnings that is indefinitely reinvested outside the U.S. The Company reassess 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 judgment.

BUSINESS COMBINATION

BUSINESS COMBINATION	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
BUSINESS COMBINATION	BUSINESS COMBINATION On September 29, 2017, the Company completed the combination of the businesses in the Company's HomeAdvisor segment and Angie's List under a new publicly traded company called ANGI Homeservices. Through the Combination, ANGI Homeservices acquired 100% of the common stock of Angie's List on September 29, 2017 for a total purchase price valued at $781.4 million . Angie’s List is a nationwide marketplace for local services where consumers can research, hire, rate and review the providers of these services. Ratings and reviews assist members in identifying and hiring a provider for their local service needs. Angie’s List's services are provided in markets located across the continental United States. 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. 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 $78.0 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 vested equity awards, which were converted into ANGI Homeservices' equity awards, and the acceleration of previously issued Angie's List equity awards held by employees terminated 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 . December 31, 2017 2016 (In thousands) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to IAC shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to IAC shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to IAC shareholders $ 4.27 $ (1.79 ) TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION ANGI Homeservices segment During the year ended December 31, 2017 , the Company incurred $44.1 million in costs related to the Combination (including severance, retention, transaction and integration related costs) as well as deferred revenue write-offs of $7.8 million . The Company also incurred $122.1 million in stock-based compensation expense during 2017 related to the modification of previously issued HomeAdvisor vested and unvested equity 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. See " Note 4—Business Combination " for additional information on the Combination. A summary of the costs incurred, payments made and the related accrual for ANGI Homeservices at December 31, 2017 is presented below. Year Ended December 31, 2017 (In thousands) Transaction and integration related costs $ 44,101 Stock-based compensation expense 122,066 Total $ 166,167 December 31, 2017 (In thousands) Charges incurred $ 44,101 Payments made (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, 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, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill and intangible assets, net are as follows: December 31, 2017 2016 (In thousands) Goodwill $ 2,559,066 $ 1,924,052 Intangible assets with indefinite lives 459,143 320,645 Intangible assets with definite lives, net of accumulated amortization 204,594 34,806 Total goodwill and intangible assets, net $ 3,222,803 $ 2,279,503 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 Video 25,239 70,369 — — 95,608 Applications 447,242 — — — 447,242 Other 74,422 — (74,430 ) 8 — Total $ 1,924,052 $ 661,396 $ (74,430 ) $ 48,048 $ 2,559,066 The additions primarily relate to the acquisitions of Angie's List, MyBuilder and HomeStars (included in the ANGI Homeservices segment), and Livestream (included in the Video segment). The deductions relate to the sale of The Princeton Review (included in the 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, 2016 : Balance at Additions Deductions Impairment Foreign Balance at (In thousands) Match Group $ 1,218,607 $ 603 $ (2,983 ) $ — $ (9,689 ) $ 1,206,538 ANGI Homeservices 150,251 21,985 — — (1,625 ) 170,611 Video 15,590 9,649 — — — 25,239 Applications 447,242 — — — — 447,242 Publishing 277,192 — (1,968 ) (275,367 ) 143 — Other 136,482 — (62,860 ) — 800 74,422 Total $ 2,245,364 $ 32,237 $ (67,811 ) $ (275,367 ) $ (10,371 ) $ 1,924,052 The additions primarily relate to the acquisitions of MyHammer Holding AG (included in the ANGI Homeservices segment) and VHX (included in the Video segment). The deductions primarily relate to the sales of PriceRunner and ShoeBuy (both included in the Other segment). During the second quarter of 2016, the Company recorded impairment charges related to the entire $275.4 million balance of the Publishing reporting unit goodwill. The goodwill impairment charge at Publishing was driven by the impact from the new Google contract, traffic trends and monetization challenges and the corresponding impact on the then estimated fair value. The December 31, 2017 and 2016 goodwill balance reflects accumulated impairment losses of $598.0 million , $529.1 million and $11.6 million at Publishing, Applications and Electus (included in the Video segment), respectively. Intangible assets with indefinite lives are trade names and trademarks acquired in various acquisitions. During the second quarter of 2016, the Company changed the classification of certain intangibles from indefinite-lived to definite-lived at Publishing. At December 31, 2017 and 2016 , intangible assets with definite lives are as follows: December 31, 2017 Gross Accumulated Net Weighted-Average (In thousands) Contractor and service professional relationships and other $ 102,997 $ (13,252 ) $ 89,745 3.0 Technology 115,200 (37,357 ) 77,843 4.8 Customer lists and user base 23,468 (5,401 ) 18,067 2.2 Content 5,000 (3,973 ) 1,027 5.0 Trade names 16,986 (13,634 ) 3,352 2.6 Memberships 15,900 (1,340 ) 14,560 3.0 Total $ 279,551 $ (74,957 ) $ 204,594 3.7 December 31, 2016 Gross Accumulated Net Weighted-Average (In thousands) Contractor relationships and other $ 7,230 $ (2,612 ) $ 4,618 4.5 Technology 38,602 (27,667 ) 10,935 3.4 Customer lists and user base 12,485 (9,997 ) 2,488 3.7 Content 14,802 (8,965 ) 5,837 4.3 Trade names 63,855 (52,927 ) 10,928 1.8 Total $ 136,974 $ (102,168 ) $ 34,806 2.8 At December 31, 2017 , 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) 2018 $ 72,395 2019 56,624 2020 44,438 2021 12,529 2022 10,650 Thereafter 7,958 Total $ 204,594

MARKETABLE SECURITIES

MARKETABLE SECURITIES	12 Months Ended
	Dec. 31, 2017
Marketable Securities [Abstract]
MARKETABLE SECURITIES	MARKETABLE SECURITIES At December 31, 2017 , current available-for-sale marketable securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 4,995 $ — $ — $ 4,995 Total marketable securities $ 4,995 $ — $ — $ 4,995 The contractual maturities of debt securities classified as current available-for-sale at December 31, 2017 are due within one year. There are no investments in available-for-sale marketable debt securities that are in an unrealized loss position as of December 31, 2017 . At December 31, 2016 , current available-for-sale marketable securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 49,797 $ — $ — $ 49,797 Treasury discount notes 34,978 — (4 ) 34,974 Corporate debt securities 4,575 2 (6 ) 4,571 Total marketable securities $ 89,350 $ 2 $ (10 ) $ 89,342 The aggregate fair value of available-for-sale marketable debt securities with unrealized losses is $37.0 million as of December 31, 2016 . 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, 2016 . The unrealized gains and losses in the above table at December 31, 2016 are included in "Accumulated other comprehensive loss" in the accompanying consolidated balance sheet. The following table presents the proceeds from maturities and sales of available-for-sale marketable securities and the related gross realized gains: December 31, 2017 2016 2015 (In thousands) Proceeds from maturities and sales of available-for-sale marketable securities $ 114,350 $ 279,485 $ 218,976 Gross realized gains — 3,556 443 Gross realized gains from the maturities and sales of available-for-sale marketable securities are included in "Other (expense) income, net" in the accompanying consolidated statement of operations. There were no gross realized losses from the maturities and sales of available-for-sale marketable securities for the years ended December 31, 2017 , 2016 and 2015 . However, during the second quarter of 2015 , the Company recognized $0.3 million in losses that were deemed to be other-than-temporary related to various corporate debt securities that were expected to be sold by the Company, in part, to fund its cash needs related to Match Group's acquisition of PlentyOfFish for $575 million .

LONG-TERM INVESTMENTS

LONG-TERM INVESTMENTS	12 Months Ended
	Dec. 31, 2017
Long-term Investments [Abstract]
LONG-TERM INVESTMENTS	LONG-TERM INVESTMENTS Long-term investments consist of: December 31, 2017 2016 (In thousands) Cost method investments $ 63,418 $ 116,133 Equity method investments 1,559 6,677 Total long-term investments $ 64,977 $ 122,810 Cost method investments In 2017 , 2016 and 2015 , the Company recorded $9.5 million , $10.0 million and $4.5 million , respectively, of other-than-temporary impairment charges for certain cost method investments as a result of our assessment of the near-term prospects and financial condition of the investees. These charges are included in "Other (expense) income, 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 (expense) income, net" in the accompanying consolidated statement of operations. Equity method investments In 2017 and 2016 , the Company recorded other-than-temporary impairment charges on certain of its investments of $2.7 million and $0.6 million , respectively. These charges are included in "Other (expense) income, net" in the accompanying consolidated statement of operations.

FAIR VALUE MEASUREMENTS AND FIN

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS	FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS The following tables present the Company's financial instruments that are measured at fair value on a recurring basis: December 31, 2017 Quoted Market Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Measurements (In thousands) Assets: Cash equivalents: Money market funds $ 780,425 $ — $ — $ 780,425 Time deposits — 60,000 — 60,000 Treasury discount notes 100,457 — — 100,457 Commercial paper — 215,325 — 215,325 Certificates of deposit — 6,195 — 6,195 Marketable securities: Commercial paper — 4,995 — 4,995 Total $ 880,882 $ 286,515 $ — $ 1,167,397 Liabilities: Contingent consideration arrangements $ — $ — $ (2,647 ) $ (2,647 ) December 31, 2016 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 667,662 $ — $ — $ 667,662 Time deposits — 79,000 — 79,000 Treasury discount notes 24,991 — — 24,991 Commercial paper — 123,640 123,640 Marketable securities: Commercial paper — 49,797 49,797 Treasury discount notes 34,974 — — 34,974 Corporate debt securities — 4,571 — 4,571 Total $ 727,627 $ 257,008 $ — $ 984,635 Liabilities: Contingent consideration arrangements $ — $ — $ (33,871 ) $ (33,871 ) The following table presents the changes in the Company's financial instruments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3): For the Year Ended December 31, 2017 2016 Contingent Auction Rate Contingent Consideration Arrangements (In thousands) Balance at January 1 $ (33,871 ) $ 4,050 $ (33,873 ) Total net (losses) gains: Included in earnings: Fair value adjustments (5,801 ) — (2,555 ) Included in other comprehensive (loss) income (1,404 ) 5,950 (1,571 ) Fair value at date of acquisition — — (185 ) Settlements 38,429 — 2,180 Proceeds from sale — (10,000 ) — Other — — 2,133 Balance at December 31 $ (2,647 ) $ — $ (33,871 ) Contingent consideration arrangements As of December 31, 2017 , there are three contingent consideration arrangements related to business acquisitions. Two of the contingent consideration arrangements have limits as to the maximum amount that can be paid. The maximum contingent payments related to these arrangements is $33.0 million and the gross fair value of these arrangements, before the unamortized discount, at December 31, 2017 is $3.0 million . No payment is expected for the one contingent consideration arrangement without a limit on the maximum earnout. The contingent consideration arrangements are based upon earnings performance and/or operating metrics. The Company generally determined 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 both December 31, 2017 and 2016 reflect discount rates of 12% . The fair value of the 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, 2017 and 2016 includes a current portion of $0.6 million and $33.4 million , respectively, and non-current portion of $2.0 million and $0.4 million , respectively, 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, 2017 December 31, 2016 Carrying Fair Carrying Fair (In thousands) Current portion of long-term debt $ (13,750 ) $ (13,802 ) $ (20,000 ) $ (20,311 ) Long-term debt, net (1,979,469 ) (2,168,108 ) (1,582,484 ) (1,657,861 ) The fair value of long-term debt, including the current portion, is estimated using market prices or indices for similar liabilities and takes into consideration other factors such as credit quality and maturity, which are Level 3 inputs.

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt consists of: December 31, 2017 2016 (In thousands) Match Group Debt: Match Group Term Loan due November 16, 2022 $ 425,000 $ 350,000 6.75% Senior Notes due December 15, 2022 (the "Match Group 6.75% Senior Notes"); interest payable each June 15 and December 15 — 445,172 6.375% Senior Notes due June 1, 2024 (the "Match Group 6.375% Senior Notes"); interest payable each June 1 and December 1 400,000 400,000 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 450,000 — Total Match Group long-term debt 1,275,000 1,195,172 Less: unamortized original issue discount and original issue premium, net 8,668 5,245 Less: unamortized debt issuance costs 13,636 13,434 Total Match Group debt, net 1,252,696 1,176,493 ANGI Homeservices Debt: ANGI Homeservices Term Loan due November 1, 2022 275,000 — Less: current portion of ANGI Homeservices long-term debt 13,750 — Less: unamortized debt issuance costs 2,938 — Total ANGI Homeservices debt 258,312 — IAC Debt: 0.875% Exchangeable Senior Notes due October 1, 2022 (the "Exchangeable Notes"); interest payable each April 1 and October 1, which commences on April 1, 2018 517,500 — 4.75% Senior Notes due December 15, 2022 (the "4.75% Senior Notes"); interest payable each June 15 and December 15 34,859 38,109 4.875% Senior Notes due November 30, 2018 (the "4.875% Senior Notes"); interest payable each May 30 and November 30 — 390,214 Total IAC long-term debt 552,359 428,323 Less: current portion of IAC long-term debt — 20,000 Less: unamortized original issue discount 67,158 — Less: unamortized debt issuance costs 16,740 2,332 Total IAC debt, net 468,461 405,991 Total long-term debt, net $ 1,979,469 $ 1,582,484 Match Group Senior Notes : The outstanding balance of the Match Group 6.75% Senior Notes of $445.2 million was redeemed on December 17, 2017 with the proceeds from the issuance of the Match Group 5.00% Senior Notes and cash on hand. The Match Group 6.375% Senior Notes were issued on June 1, 2016. The proceeds of $400 million were used to prepay a portion of indebtedness outstanding under the Match Group 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. 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, Match Group completed a private offering of $450 million aggregate principal amount of its 5.00% Senior Notes due December 15, 2027. The proceeds from these notes, along with cash on hand, were used to redeem the outstanding balance of the Match Group 6.75% Senior Notes. At any time prior to December 15, 2022, the Match Group 5.00% 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. 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 Match Group 6.375% and 5.00% Senior Notes (i) contain covenants that would limit Match Group's ability to pay dividends or to make distributions and repurchase or redeem Match Group stock in the event a default has occurred or Match Group's leverage ratio (as defined in the indentures) exceeds 5.0 to 1.0 and (ii) are ranked equally with each other. At December 31, 2017 , there were no limitations pursuant thereto. There are additional covenants that limit Match Group's ability and the ability of its subsidiaries to, among other things, (i) incur indebtedness, make investments, or sell assets in the event Match Group is not in compliance with certain ratios set forth in the indenture, and (ii) incur liens, enter into agreements restricting Match Group subsidiaries' ability to pay dividends, enter into transactions with affiliates and consolidate, merge or sell substantially all of their assets. Match Group Term Loan and Match Group Credit Facility : On November 16, 2015, under a credit agreement (the "Match Group Credit Agreement"), Match Group borrowed $800 million in the form of a term loan (the "Match Group Term Loan"). During 2016, Match Group made $450 million of principal payments, $400 million of which was funded from proceeds of the 6.375% Senior Notes (described above). On August 14, 2017, Match Group increased its Term Loan by $75 million to $425 million , repriced the outstanding balance at LIBOR plus 2.50% and reduced the LIBOR floor to 0.00% . The Match Group Term Loan provides for additional 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 Match Group Credit Agreement. The interest rate on the Match Group Term Loan at December 31, 2017 is 3.85% . Interest payments are due at least quarterly through the term of the loan. Match Group has a $500 million revolving credit facility (the "Match Group Credit Facility") that expires on October 7, 2020. At December 31, 2017 and 2016 , there were no outstanding borrowings under the Match Group Credit Facility. The annual commitment fee on undrawn funds based on the current leverage ratio is 30 basis points. Borrowings under the Match Group Credit Facility bear interest, at Match Group'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 Match Group's consolidated net leverage ratio. The terms of the Match Group Credit Facility require Match Group 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 2.5 to 1.0 (in each case as defined in the agreement). There are additional covenants under the Match Group Credit Facility and the Match Group Term Loan that limit the ability of Match Group and its subsidiaries to, among other things, incur indebtedness, pay dividends or make distributions. While the Match Group Term Loan remains outstanding, these same covenants under the Match Group Credit Agreement are more restrictive than the covenants that are applicable to the Match Group Credit Facility. Obligations under the Match Group Credit Facility and Match Group Term Loan are unconditionally guaranteed by certain Match Group wholly-owned domestic subsidiaries, and are also secured by the stock of certain Match Group domestic and foreign subsidiaries. The Match Group Term Loan and outstanding borrowings, if any, under the Match Group Credit Facility rank equally with each other, and have priority over the Match Group 6.375% and 5.00% Senior Notes to the extent of the value of the assets securing the borrowings under the Match Group Credit Agreement. ANGI Homeservices Term Loan: On November 1, 2017, ANGI Homeservices borrowed $275 million under a five-year term loan facility ("ANGI Homeservices Term Loan"). The ANGI Homeservices Term Loan is guaranteed by ANGI Homeservices' wholly-owned material domestic subsidiaries and is secured by substantially all assets of ANGI Homeservices and the guarantors, subject to certain exceptions. The ANGI Homeservices Term Loan currently bears interest at LIBOR plus 2.00% , or 3.38% at December 31, 2017, which is subject to change based on ANGI Homeservices' consolidated net leverage ratio. 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, 2.5% in the fourth year and 3.75% in the fifth year are required. A portion of the proceeds of the loan were used to repay two intercompany notes outstanding to IAC and its subsidiaries and the remaining proceeds will be used for general corporate purposes. See " Note 17—Related Party Transactions " for further information on the intercompany notes. There are additional covenants under the ANGI Homeservices Term Loan that limit the ability of ANGI Homeservices and its subsidiaries to, among other things, incur indebtedness, pay dividends or make distributions. Obligations under the ANGI Homeservices Term Loan are unconditionally guaranteed by certain ANGI Homeservices wholly-owned domestic subsidiaries, and are also secured by the stock of certain ANGI Homeservices domestic and foreign subsidiaries. IAC Exchangeable Notes: On October 2, 2017, IAC FinanceCo, Inc., a direct, wholly-owned subsidiary of the Company, completed a private offering of $517.5 million aggregate principal amount of its 0.875% Exchangeable Senior Notes due October 1, 2022 (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 conversion, the Company has the right to settle the conversion of each $1,000 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 commencing after the calendar quarter ending on December 31, 2017 (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; (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. The net proceeds from the sale of the Exchangeable Notes were approximately $499.5 million , after deducting fees and expenses. The net proceeds from the offering were: • used to pay the net premium of $50.7 million on the Exchangeable Note Hedge and Warrant (defined below); and • loaned to IAC, which repaid the outstanding balance of the 4.875% Senior Notes of $361.9 million , plus accrued interest of $8.8 million . The 4.875% Senior Notes were redeemed on November 30, 2017. 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 "Warrant"). The Exchangeable Note Hedge is expected to reduce the potential dilutive effect of 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 would separately 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 applicable 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. The Company incurred cash and non-cash interest expense of $4.3 million in 2017 for the Exchangeable Notes. As of December 31, 2017 , the unamortized discount amount totaled $67.2 million resulting in a net carrying value of the liability component of $450.3 million . IAC Senior Notes : The 4.75% Senior Notes were issued by IAC on December 21, 2012. These Notes are unconditionally guaranteed by certain wholly-owned domestic subsidiaries, which are designated as guarantor subsidiaries. See " Note 21—Guarantor and Non-Guarantor Financial Information " for financial information relating to guarantors and non-guarantors. The indenture governing the 4.75% Senior Notes was amended to eliminate substantially all of the restrictive covenants contained therein in connection with the Match Exchange Offer. We may redeem the 4.75% Senior Notes at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed 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 : IAC has a $300 million revolving credit facility (the "IAC Credit Facility") that expires October 7, 2020. At December 31, 2017 and 2016 , there were no outstanding borrowings under the IAC Credit Facility. The annual commitment fee on undrawn funds is currently 25 basis points, and is based on the leverage ratio (as defined in the agreement) most recently reported. 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 leverage ratio. The terms of the IAC Credit Facility require that the Company maintains a leverage ratio of not more than 3.25 to 1.0 and restrict our ability to incur additional indebtedness. Borrowings under the IAC Credit Facility are unconditionally guaranteed by 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. The 4.75% Senior Notes are subordinate to the outstanding borrowings under the IAC Credit Facility to extent of the value of the assets securing such borrowings. On October 2, 2017, IAC Group, LLC ("IAC Group"), a wholly-owned subsidiary of the Company, entered into a joinder agreement by and among IAC Group, the Company, and each of the other loan parties party to the IAC Credit Facility. Pursuant to the joinder agreement, IAC Group became the successor borrower under the IAC Credit Facility and IAC's obligations under the credit agreement were terminated. Borrowings under the IAC Credit Facility are still unconditionally guaranteed by the same domestic subsidiaries that guarantee the 4.75% Senior Notes and is still secured by the stock of certain of our domestic and foreign subsidiaries. Long-term debt maturities: Years Ending December 31, (In thousands) 2018 $ 13,750 2019 13,750 2020 13,750 2021 27,500 2022 1,183,609 2024 400,000 2027 450,000 Total 2,102,359 Less: current portion of long-term debt 13,750 Less: unamortized original issue discount 75,826 Less: unamortized debt issuance costs 33,314 Total long-term debt, net $ 1,979,469

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY Description of Common Stock and Class B Convertible Common Stock 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. Except as described herein, shares of IAC common stock and IAC Class B common stock are identical. 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 therefore. 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, 19.1 million shares of IAC common stock are reserved at December 31, 2017 . Warrants At December 31, 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. During the year ended December 31, 2017 there were no warrants exercised. No warrants were outstanding at December 31, 2016 and 2015 . See " Note 9—Long-term Debt " for additional information on the Company's Exchangeable Notes. Common Stock Repurchases During 2017 , 2016 and 2015 , the Company repurchased 0.7 million , 6.3 million and 3.0 million shares of IAC common stock for aggregate consideration, on a trade date basis, of $50.1 million , $315.3 million and $200.0 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, 2017 , the Company has approximately 8.6 million shares remaining in its share repurchase authorization.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	12 Months Ended
	Dec. 31, 2017
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, 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 ) (a) (3,360 ) Net current period other comprehensive income (loss) 66,581 (4,026 ) 62,555 Balance at December 31 $ (103,568 ) $ — $ (103,568 ) _________________________ (a) Amount includes a tax benefit of $3.8 million . At December 31, 2017 , there was no tax benefit or provision on the accumulated other comprehensive loss. 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 ) (b) 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 ) _________________________ (b) Amount is net of a tax provision of $0.2 million . Year Ended December 31, 2015 Foreign Currency Translation Adjustment Unrealized (Losses) Gain On Available-For-Sale Securities Accumulated Other Comprehensive Loss (In thousands) Balance at January 1 $ (86,848 ) $ (852 ) $ (87,700 ) Other comprehensive (loss) income before reclassifications, net of tax provision of $0.6 million related to unrealized gains on available-for-sale securities (65,606 ) 3,537 (62,069 ) Amounts reclassified to earnings (2,191 ) (143 ) (c) (2,334 ) Net current period other comprehensive (loss) income (67,797 ) 3,394 (64,403 ) Balance at December 31 $ (154,645 ) $ 2,542 $ (152,103 ) _________________________ (c) Amount is net of a tax provision of $0.1 million .

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 Basic Diluted Basic Diluted Basic Diluted (In thousands, except per share data) Numerator: Net earnings (loss) $ 358,008 $ 358,008 $ (16,151 ) $ (16,151 ) $ 113,374 $ 113,374 Net (earnings) loss attributable to noncontrolling interests (53,084 ) (53,084 ) (25,129 ) (25,129 ) 6,098 6,098 Impact from public subsidiaries' dilutive securities (a) — (33,531 ) — — — (1,799 ) Net earnings (loss) attributable to IAC shareholders $ 304,924 $ 271,393 $ (41,280 ) $ (41,280 ) $ 119,472 $ 117,673 Denominator: Weighted average basic shares outstanding 80,089 80,089 80,045 80,045 82,944 82,944 Dilutive securities (b) (c) (d) (e) (f) (g) — 5,221 — — — 5,323 Denominator for earnings per share—weighted average shares (b) (c) (d) (e) (f) (g) 80,089 85,310 80,045 80,045 82,944 88,267 Earnings (loss) per share attributable to IAC shareholders: Earnings (loss) per share $ 3.81 $ 3.18 $ (0.52 ) $ (0.52 ) $ 1.44 $ 1.33 __________________________________________________________________ (a) The amount for the years ended December 31, 2017 and 2015 reflects the reduction in Match Group's earnings (after its IPO on November 24, 2015) attributable to IAC from the assumed exercise of Match Group dilutive securities under the if-converted method. For the year ended December 31, 2016 , the impact on earnings related to Match Group's dilutive securities under the if-converted method is excluded because it would have been anti-dilutive due to the Company's net loss. (b) Dilutive securities for the year ended December 31, 2017 , include the impact from the assumed exercise of ANGI Homeservices dilutive securities under the if-converted method, as it is more dilutive for IAC to settle certain ANGI Homeservices equity awards. The impact on earnings of ANGI Homeservices 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, conversion of the Company's Exchangeable Notes and vesting of restricted stock units ("RSUs"). For the years ended December 31, 2017 and 2015 , 6.9 million and 1.2 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 the years ended December 31, 2017 and 2015 , 0.1 million and 0.6 million shares, respectively, 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; the Exchangeable Notes will only become dilutive once the price of IAC common stock exceeds the approximate $152.18 per share exchange price of the Exchangeable Notes. (g) See " Note 13—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, 2017
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, PSUs and restricted stock, 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, 2017 , there are 2.5 million shares available for grant under the plans. The plans were adopted in 2008 and 2013, 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, 2017 , there is $423.2 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 2.5 years. The total income tax benefit recognized in the accompanying consolidated statement of operations for the years ended December 31, 2017 , 2016 and 2015 related to stock-based compensation is $423.0 million , $34.8 million and $36.6 million , respectively. The increase in total income tax benefit recognized during 2017 is due to the adoption of ASU 2019-06 and the recognition of excess tax benefits attributable to stock-based compensation included as a component of the current year provision for income taxes rather than recognized in equity. The Company will recognize a corporate income tax deduction based on the intrinsic value of the stock options exercised in 2017, however, there will be some delay in the timing of the realization of the cash benefit of the income tax deduction because it will be dependent upon the amount and timing of future taxable income and the timing of estimated income tax payments. The income tax benefit to be realized on stock option deductions, including those net settled, for the year ended December 31, 2017, is $411.6 million . The income tax benefit realized on stock option deductions, including those net settled, for the years ended December 31, 2016 and 2015 are $63.4 million and $69.3 million , respectively. IAC Stock Options Stock options outstanding at December 31, 2017 and changes during the year ended December 31, 2017 are as follows: December 31, 2017 Shares Weighted Weighted Aggregate (Shares and intrinsic value in thousands) Options outstanding at January 1, 2017 8,058 $ 52.41 Granted 1,153 76.62 Exercised (2,443 ) 41.30 Forfeited (179 ) 59.34 Expired (3 ) 56.31 Options outstanding at December 31, 2017 6,586 $ 60.57 7.0 $ 406,527 Options exercisable 2,920 $ 55.28 5.6 $ 195,677 The aggregate intrinsic value in the table above represents the difference between IAC's closing stock price on the last trading day of 2017 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, 2017 . The total intrinsic value of stock options exercised during the years ended December 31, 2017 , 2016 and 2015 is $164.6 million , $17.1 million and $53.0 million , respectively. The following table summarizes the information about stock options outstanding and exercisable at December 31, 2017 : Options Outstanding Options Exercisable Range of Exercise Prices Outstanding at Weighted- Weighted- Exercisable at Weighted- Weighted- (Shares in thousands) $10.01 to $20.00 38 0.9 $ 16.67 38 0.9 $ 16.67 $20.01 to $30.00 66 1.5 21.15 66 1.5 21.15 $30.01 to $40.00 415 3.3 32.31 415 3.3 32.31 $40.01 to $50.00 1,862 6.8 43.42 870 5.3 44.86 $50.01 to $60.00 263 4.0 59.47 259 4.0 59.48 $60.01 to $70.00 1,474 7.2 65.00 615 6.9 65.49 $70.01 to $80.00 1,952 8.4 75.30 407 7.3 74.16 $80.01 to $90.00 500 7.3 84.31 250 7.3 84.31 Greater than $90.01 16 9.9 125.06 — — — 6,586 7.0 $ 60.57 2,920 5.6 $ 55.28 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 2017 , 2016 and 2015 , 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, 2017 2016 2015 Expected volatility 29 % 29 % 28 % Risk-free interest rate 2.0 % 1.2 % 1.6 % Expected term 5.2 years 4.8 years 5.3 years Dividend yield — % — % 2.0 % During 2015, the Company granted market-based stock options to certain employees. These awards 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 2017. The service requirement provides that these awards vest in four equal annual installments beginning on the first anniversary of the grant date. The grant date fair value of each 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 these awards included a weighted average expected volatility of 27% , risk-free interest rate of 2.3% and a 1.8% dividend yield. The expected term of these awards was derived from the output of the option valuation model. Expense is recognized over the longer of the vesting period of each of the four installments or the expected term. The weighted average expected term of these awards is 4 years . Approximately 1.2 million , 1.7 million and 2.5 million stock options were granted by the Company during the years ended December 31, 2017 , 2016 and 2015 , respectively. The weighted average fair value of stock options granted during the years ended December 31, 2017 , 2016 and 2015 with exercise prices equal to the market prices of IAC's common stock on the date of grant are $22.94 , $12.34 and $15.24 , respectively. During the year ended December 31, 2015 , the weighted average exercise price and weighted average fair value of stock options granted with exercise prices greater than the market value of IAC's common stock on the date of grant are $84.31 and $12.00 , respectively. Cash received from stock option exercises for the years ended December 31, 2017 , 2016 and 2015 are $82.4 million , $25.8 million and $27.3 million , respectively. 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, 2017 and changes during the year ended December 31, 2017 are as follows: RSUs PSUs Number Weighted Number Weighted (Shares in thousands) Unvested at January 1, 2017 526 $ 57.41 — $ — Granted 174 100.54 130 76.00 Vested (340 ) 54.66 — — Forfeited — — — — Unvested at December 31, 2017 360 $ 80.81 130 $ 76.00 The weighted average fair value of RSUs and PSUs granted during the years ended December 31, 2017 , 2016 and 2015 based on market prices of IAC's common stock on the grant date was $90.04 , $46.92 and $67.71 , respectively. The total fair value of RSUs and PSUs that vested during the years ended December 31, 2017 , 2016 and 2015 was $32.5 million , $13.5 million and $16.8 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, Match Group and ANGI Homeservices. Match Group and ANGI Homeservices stock-based awards are issued pursuant to their respective stock incentive plans. IAC has granted stock options and 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 options and 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 interests are ultimately settled in IAC common stock with fair market value generally determined by negotiation or arbitration, at various dates through 2027 . These equity awards are settled on a net basis, with the award holder entitled to receive a payment in 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 shares ultimately needed to settle these awards may vary significantly from the estimated numbers 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, 2017 is 0.1 million shares. Withholding taxes, which will be paid by the Company on behalf of the employees upon exercise, would have been $15.2 million at December 31, 2017 , assuming a 50% withholding rate. Match Group Following the completion of the Match Group IPO, equity awards that related to certain subsidiaries (principally Tinder, Inc.) of Match Group were settleable, at IAC's election, in shares of IAC common stock or Match Group common stock. Pursuant to the Employee Matters Agreement between IAC and Match Group, to the extent shares of IAC common stock are issued in settlement of these awards, Match Group reimburses IAC for the cost of those shares in cash or by issuing IAC shares of Match Group common stock. In July 2017, Tinder was merged into Match Group and as a result, all Tinder denominated equity awards were converted into Match Group tandem stock options ("Tandem Awards"). All of the Match Group Tandem Awards exercised during 2017 were exercised on a net basis and were settled in IAC common shares; the Company issued 2.0 million shares of its common stock to settle these awards and Match Group issued 11.3 million shares of its common stock to IAC as reimbursement. During 2017 , Match Group also purchased certain fully vested Tandem Awards. During 2017 , Match Group 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. Assuming all vested and unvested Match Group Tandem Awards outstanding on December 31, 2017 were exercised on a net basis on that date and settled with IAC stock, 0.8 million IAC common shares would have been issued in settlement. Match Group would have remitted $102.4 million in cash in withholding taxes (assuming a 50% withholding rate) on behalf of the employees and issued 3.3 million of its common shares to IAC as reimbursement. During 2016 and 2015 , the Company granted a nominal amount of IAC denominated market-based awards to certain Match Group employees. The number of awards that ultimately vest is dependent upon Match Group'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 Match Group'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 Homeservices In connection with the Combination, previously issued stock appreciation rights that related to the common stock of HomeAdvisor (US) were converted into stock appreciation rights that are exercisable for Class A shares of ANGI Homeservices. IAC has the right to settle these awards using shares of IAC common stock. To the extent shares of IAC common stock are issued in settlement of these awards, ANGI Homeservices will reimburse IAC by issuing to IAC additional Class A shares of ANGI Homeservices common stock pursuant to the Employee Matters Agreement between IAC and ANGI Homeservices. These equity awards are settled on a net basis, with the award holder entitled to receive a payment in shares equal to the intrinsic value of the award at exercise less an amount equal to the required cash tax withholding payment. Assuming all vested and unvested stock appreciation rights outstanding on December 31, 2017 were exercised on a net basis and settled using IAC stock, 1.4 million IAC common shares would have been issued in settlement. ANGI Homeservices would have remitted $171.3 million in cash in withholding taxes (assuming a 50% withholding rate) on behalf of the employees and issued 16.4 million of its common shares to IAC as reimbursement. Modification of awards In connection with the Combination, the previously issued HomeAdvisor (US) stock appreciation rights were converted into ANGI Homeservices' equity awards resulting in a modification charge of $217.7 million of which $93.4 million was recognized as stock-based compensation expense in the year ended December 31, 2017 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 subsidiary 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 $0.7 million and $6.3 million were recognized as stock-based compensation in the years ended December 31, 2017 and 2016 , respectively, and $0.1 million will be recognized over the remaining vesting period of the modified awards. During the first quarter of 2015 , the Company modified certain subsidiary denominated equity awards resulting in a modification charge of $5.8 million of which $0.2 million , $0.6 million and $3.5 million was recognized in 2017 , 2016 and 2015 , respectively, and the remaining charge will be recognized over the remaining vesting period of the modified awards. During the third quarter of 2015 , the Company modified certain subsidiary denominated vested equity awards and recognized a modification charge of $6.8 million . During the fourth quarter of 2015 , the Company repurchased certain subsidiary denominated vested equity awards in exchange for $23.4 million in cash and fully vested modified equity awards and recognized a modification charge of $7.7 million . These modification charges are included in stock-based compensation in the year ended December 31, 2015 . 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 , Match Group settled the vested portion of the award for cash of $13.4 million . In the third quarter of 2017 , the award was modified and Match Group settled the remaining portion of the award for cash of $33.9 million .

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2017
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 Other reportable segment, do not meet the quantitative thresholds that require presentation as separate reportable segments. Years Ended December 31, 2017 2016 2015 (In thousands) Revenue: Match Group $ 1,330,661 $ 1,118,110 $ 909,705 ANGI Homeservices 736,386 498,890 361,201 Video 276,994 228,649 213,317 Applications 577,998 604,140 760,748 Publishing 361,837 407,313 691,686 Other (a) 23,980 283,365 294,821 Inter-segment elimination (617 ) (585 ) (545 ) Total $ 3,307,239 $ 3,139,882 $ 3,230,933 ___________________ (a) The Other segment consists of the results of PriceRunner, ShoeBuy and The Princeton Review for periods prior to the sales of these businesses, which occurred on March 18, 2016, December 30, 2016 and March 31, 2017, respectively. Beginning in the second quarter of 2017, as a result of the sales of these businesses, the Other segment does not include any financial results. Years Ended December 31, 2017 2016 2015 (In thousands) Operating Income (Loss): Match Group $ 360,517 $ 315,549 $ 212,981 ANGI Homeservices (149,176 ) 25,363 (1,568 ) Video (35,659 ) (27,656 ) (38,756 ) Applications 130,176 109,663 175,145 Publishing 15,670 (334,417 ) (26,692 ) Other (5,621 ) (11,678 ) (28,611 ) Corporate (127,441 ) (109,449 ) (112,911 ) Total $ 188,466 $ (32,625 ) $ 179,588 Years Ended December 31, 2017 2016 2015 (In thousands) Adjusted EBITDA: (b) Match Group $ 468,941 $ 403,380 $ 284,554 ANGI Homeservices 37,858 45,851 16,713 Video (30,446 ) (21,247 ) (38,384 ) Applications 136,757 132,276 184,258 Publishing 31,470 (7,571 ) 87,788 Other (1,532 ) 1,802 4,734 Corporate (67,755 ) (53,272 ) (53,873 ) Total $ 575,293 $ 501,219 $ 485,790 December 31, 2017 2016 (In thousands) Segment Assets: (c) Match Group $ 467,338 $ 422,509 ANGI Homeservices 264,450 74,106 Video 129,855 225,519 Applications 345,532 98,460 Publishing 182,949 398,958 Other — 15,372 Corporate 873,392 822,687 Total $ 2,263,516 $ 2,057,611 Years Ended December 31, 2017 2016 2015 (In thousands) Capital expenditures: Match Group $ 28,833 $ 46,098 $ 25,246 ANGI Homeservices 26,837 16,660 10,170 Video 400 2,508 2,466 Applications 227 1,196 4,681 Publishing 850 2,093 6,283 Other 536 5,712 7,085 Corporate 17,840 3,772 6,118 Total $ 75,523 $ 78,039 $ 62,049 _______________________________________________________________________________ (b) 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 business as a whole and our individual business segments, and this measure is one of the primary metrics by 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, and we believe that by excluding these items, Adjusted EBITDA corresponds more closely to the cash operating income generated from our business, from which capital investments are made and debt is serviced. Adjusted EBITDA has certain limitations in that it does not take into account the impact to IAC's statement of operations of certain expenses. (c) 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. The following table presents the revenue of the Company's principal segments disaggregated by type of service: Years Ended December 31, 2017 2016 2015 (In thousands) Match Group Direct revenue $ 1,281,249 $ 1,067,364 $ 866,583 Indirect revenue (principally advertising revenue) 49,412 50,746 43,122 Total Match Group revenue $ 1,330,661 $ 1,118,110 $ 909,705 ANGI Homeservices Marketplace: Consumer connection revenue (d) $ 521,481 $ 382,466 $ 269,309 Membership subscription revenue 56,135 43,573 24,164 Other revenue 3,798 2,827 3,423 Marketplace revenue 581,414 428,866 296,896 Advertising & Other revenue (e) 97,483 32,981 32,971 North America 678,897 461,847 329,867 Consumer connection revenue (d) 40,009 28,124 23,298 Membership subscription revenue 16,596 7,936 6,921 Advertising and other revenue 884 983 1,115 Europe 57,489 37,043 31,334 Total ANGI Homeservices revenue $ 736,386 $ 498,890 $ 361,201 Applications Advertising $ 515,405 $ 552,410 $ 728,501 Subscription (including downloadable app fees) and Other 62,593 51,730 32,247 Total Applications revenue $ 577,998 $ 604,140 $ 760,748 Publishing Advertising $ 358,472 $ 405,031 $ 685,440 Other 3,365 2,282 6,246 Total Publishing revenue $ 361,837 $ 407,313 $ 691,686 _______________________________________________________________________________ (d) Fees paid by service professionals for consumer matches. (e) Includes Angie's List revenue from service professionals under contract for advertising and Angie's List membership subscription fees from consumers, as well as revenue from mHelpDesk, HomeStars and Felix. 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, 2017 2016 2015 (In thousands) Revenue United States $ 2,323,050 $ 2,318,976 $ 2,376,035 All other countries 984,189 820,906 854,898 Total $ 3,307,239 $ 3,139,882 $ 3,230,933 December 31, 2017 2016 (In thousands) Long-lived assets (excluding goodwill and intangible assets) United States $ 286,541 $ 281,725 All other countries 28,629 24,523 Total $ 315,170 $ 306,248 The following tables reconcile operating income (loss) for the Company's reportable segments and net earnings (loss) attributable to IAC shareholders to Adjusted EBITDA: Year Ended December 31, 2017 Operating Stock-Based Depreciation Amortization 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 Video (35,659 ) 401 2,167 2,645 — (30,446 ) Applications 130,176 — 3,863 2,170 548 136,757 Publishing 15,670 — 4,725 11,075 — 31,470 Other (5,621 ) 1,729 836 1,524 — (1,532 ) Corporate (127,441 ) 44,168 15,518 — — (67,755 ) Total $ 188,466 $ 264,618 $ 74,265 $ 42,143 $ 5,801 $ 575,293 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 Compensation Expense 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 Video (27,656 ) 640 1,785 4,176 (192 ) — (21,247 ) Applications 109,663 — 5,095 5,483 12,035 — 132,276 Publishing (334,417 ) — 8,531 42,948 — 275,367 (7,571 ) Other (11,678 ) 618 6,219 6,734 (91 ) — 1,802 Corporate (109,449 ) 42,276 13,901 — — — (53,272 ) Total (32,625 ) $ 104,820 $ 71,676 $ 79,426 $ 2,555 $ 275,367 $ 501,219 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 ) Year Ended December 31, 2015 Operating Stock-Based Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Goodwill Impairment Adjusted EBITDA (In thousands) Match Group $ 212,981 $ 49,401 $ 19,791 $ 13,437 $ (11,056 ) $ — $ 284,554 ANGI Homeservices (1,568 ) 7,853 6,593 3,835 — — 16,713 Video (38,756 ) 360 1,091 1,558 (2,637 ) — (38,384 ) Applications 175,145 — 4,617 6,264 (1,768 ) — 184,258 Publishing (26,692 ) — 9,577 104,903 — — 87,788 Other (28,611 ) 682 8,652 9,955 — 14,056 4,734 Corporate (112,911 ) 47,154 11,884 — — — (53,873 ) Total 179,588 $ 105,450 $ 62,205 $ 139,952 $ (15,461 ) $ 14,056 $ 485,790 Interest expense (73,636 ) Other income, net 36,938 Earnings before income taxes 142,890 Income tax provision (29,516 ) Net earnings 113,374 Net loss attributable to noncontrolling interests 6,098 Net earnings attributable to IAC shareholders $ 119,472 The following tables reconcile segment assets to total assets: December 31, 2017 Segment Assets 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 Video 129,855 3,076 95,608 1,800 23,322 253,661 Applications 345,532 7,004 447,242 60,600 847 861,225 Publishing 182,949 5,350 — 15,000 3,252 206,551 Other — — — — — — Corporate (f) 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 (g) 66,321 Total Assets $ 5,867,810 December 31, 2016 Segment Assets Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 422,509 $ 62,954 $ 1,206,538 $ 214,461 $ 3,221 $ 1,909,683 ANGI Homeservices 74,106 23,645 170,611 4,884 5,908 279,154 Video 225,519 4,750 25,239 1,800 4,167 261,475 Applications 98,460 10,559 447,242 60,600 2,481 619,342 Publishing 398,958 10,696 — 15,000 11,441 436,095 Other 15,372 6,774 74,422 23,900 7,588 128,056 Corporate (f) 822,687 186,870 — — — 1,009,557 Total $ 2,057,611 $ 306,248 $ 1,924,052 $ 320,645 $ 34,806 4,643,362 Add: Deferred tax assets (g) 2,511 Total Assets $ 4,645,873 _____________________________________ (f) Corporate assets consist primarily of cash and cash equivalents, marketable securities and IAC's headquarters building. (g) Total segment assets differ from total assets on a consolidated basis as a result of unallocated deferred tax assets.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
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 a data center lease agreement. 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) 2018 $ 38,339 2019 36,996 2020 30,594 2021 23,253 2022 19,688 Thereafter 211,649 Total $ 360,519 Expenses charged to operations under these agreements are $37.9 million , $50.8 million and $39.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The Company's most significant operating lease is a seventy-seven -year land lease for IAC's headquarters building in New York City and approximates 48% 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 $ 21,994 $ 10,816 $ — $ — $ 32,810 Letters of credit and surety bonds 576 71 — 1,939 2,586 Total commercial commitments $ 22,570 $ 10,887 $ — $ 1,939 $ 35,396 The purchase obligations principally include web hosting commitments. The letters of credit 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.

SUPPLEMENTAL CASH FLOW INFORMAT

SUPPLEMENTAL CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2017
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 $0.2 million and $27.4 million during the years ended December 31, 2016 and 2015 , respectively, in connection with various acquisitions. There were no acquisition-related contingent consideration liabilities recorded for the year ended December 31, 2017 . See " Note 8—Fair Value Measurements and Financial Instruments " for additional information on contingent consideration arrangements. On September 29, 2017, ANGI Homeservices issued 61.3 million shares of Class A common stock valued at $763.7 million in connection with the Combination. On November 16, 2015, Match Group exchanged $445.3 million of 4.75% Senior Notes for $445.2 million of Match Group 6.75% Senior Notes. Supplemental Disclosure of Cash Flow Information: Years Ended December 31, 2017 2016 2015 (In thousands) Cash paid (received) during the year for: Interest $ 92,461 $ 107,360 $ 51,666 Income tax payments 35,598 69,103 70,762 Income tax refunds (42,025 ) (23,877 ) (5,619 )

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS IAC and Match Group: IAC and Match Group, in connection with Match Group's IPO, entered into the following agreements: • A Master Transaction Agreement, under which Match Group 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 Match Group 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 Match Group's common stock and (ii) anti-dilution rights with respect to Match Group's common stock; • An Employee Matters Agreement, which governs the respective rights, responsibilities and obligations of IAC and Match Group 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 Match Group 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 Match Group, 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 Match Group may agree, and Match Group agrees to provide IAC informational technology services and such other services as to which IAC and Match Group may agree. During the years ended December 31, 2017 and 2016 , 11.9 million and 1.0 million shares, respectively, of Match Group common stock were issued to IAC pursuant to the employee matters agreement; 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 Match Group tandem stock options and equity awards denominated in shares of a subsidiary of Match Group, respectively; and 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 Match Group employees. For the years ended December 31, 2017 and 2016 , and for the period from the date of the IPO through December 31, 2015 , Match Group was charged $9.9 million , $11.8 million and $0.7 million , respectively, by the Company for services rendered pursuant to a services agreement. Included in these amounts are $5.1 million , $4.3 million and $0.3 million , respectively, for leasing of office space for certain of Match Group's businesses at properties owned by IAC. These amounts were paid in full by Match Group at December 31, 2017 and 2016 , respectively. At December 31, 2017 and 2016 , Match Group had a tax receivable of $7.3 million and $9.0 million , respectively, due from the Company pursuant to the tax sharing agreement. Refunds made by the Company during 2017 pursuant to this agreement were $10.9 million and payments made to the Company during 2016 were $19.9 million . In December 2017, international subsidiaries of Match Group agreed to sell NOLs that were not expected to be utilized to an IAC subsidiary for $0.9 million . IAC and ANGI Homeservices: IAC and ANGI Homeservices, 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 Homeservices prior to the Combination. Under the Contribution Agreement, ANGI Homeservices agrees to indemnify IAC against any losses arising out of any breach by ANGI Homeservices of the Contribution Agreement; • An Investor Rights Agreement that provides IAC with (i) specified registration and other rights relating to shares of ANGI Homeservices' common stock owned by IAC; (ii) anti-dilution rights with respect to ANGI Homeservices' common stock; and (iii) specified board matters with respect to designation of ANGI Homeservices directors; • A Services Agreement, under which IAC has agreed to provide a range of services to ANGI Homeservices, 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 Homeservices may agree. • A Tax Sharing Agreement, which governs the respective rights, responsibilities and obligations of IAC and ANGI Homeservices with respect to tax matters, including taxes attributable to ANGI Homeservices, 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 Homeservices 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 Homeservices entered into two intercompany notes (collectively referred to as "Intercompany Notes") to ANGI Homeservices 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 Homeservices 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 Homeservices Term Loan that were received on the same date. See " Note 9—Long-term Debt " for further information. For the period subsequent to the Combination through December 31, 2017 , 0.4 million shares of ANGI Homeservices 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 Homeservices employees. For the period subsequent to the Combination through December 31, 2017 , ANGI Homeservices was charged $1.7 million by the Company for services rendered pursuant to the services agreement. The amount outstanding at December 31, 2017 to IAC pursuant to the services agreement is $0.4 million . In addition, the Company has 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. IAC and Expedia: Each of IAC and Expedia has a 50% ownership interest in three aircrafts that may be used by both companies. The Company and Expedia purchased the third of these three aircrafts during the second quarter of 2017 to replace the older of the existing aircrafts, which was sold on February 13, 2018. The Company paid $17.4 million ( 50% of the total purchase price and refurbish costs) for its interest. 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, 2017 , 2016 and 2015 , total payments made to this entity by the Company were not material.

BENEFIT PLANS

BENEFIT PLANS	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 and 2015 are $11.1 million , $10.0 million and $9.1 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 2017 and 2016 are due primarily to an increase in participation in the Plan due to an increase in headcount at Match Group and ANGI Homeservices as a result of continued business growth. 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, 2017 , 2016 and 2015 are $2.5 million , $2.1 million and $2.5 million , respectively. The increase in contributions in 2017 was due, in part, to an increase in participation in the international plans due to an increase in headcount at Match Group and ANGI Homeservices as a result of business growth and acquisitions. The decrease in contributions in 2016 was due, in part, to the sale of PriceRunner.

CONSOLIDATED FINANCIAL STATEMEN

CONSOLIDATED FINANCIAL STATEMENT DETAILS	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
CONSOLIDATED FINANCIAL STATEMENT DETAILS	CONSOLIDATED FINANCIAL STATEMENT DETAILS December 31, 2017 2016 (In thousands) Other current assets: Prepaid expenses $ 49,350 $ 37,665 Income taxes receivable 33,239 41,352 Capitalized downloadable search toolbar costs, net 31,588 28,737 Production costs 18,570 39,763 Other 52,627 56,551 Other current assets $ 185,374 $ 204,068 December 31, 2017 2016 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 252,511 $ 247,563 Computer equipment and capitalized software 218,529 275,455 Furniture and other equipment 88,930 94,555 Projects in progress 19,094 13,048 Land 7,917 5,117 586,981 635,738 Accumulated depreciation and amortization (271,811 ) (329,490 ) Property and equipment, net of accumulated depreciation and amortization $ 315,170 $ 306,248 December 31, 2017 2016 (In thousands) Accrued expenses and other current liabilities: Accrued employee compensation and benefits $ 108,431 $ 106,301 Accrued advertising expense 96,445 68,916 Other 162,048 169,693 Accrued expenses and other current liabilities $ 366,924 $ 344,910 Years Ended December 31, 2017 2016 2015 (In thousands) Revenue: Service revenue $ 3,302,937 $ 2,967,474 $ 3,077,080 Product revenue 4,302 172,408 153,853 Revenue $ 3,307,239 $ 3,139,882 $ 3,230,933 Years Ended December 31, 2017 2016 2015 (In thousands) Cost of revenue: Cost of service revenue $ 647,226 $ 617,058 $ 652,137 Cost of product revenue 3,782 138,672 126,024 Cost of revenue $ 651,008 $ 755,730 $ 778,161 Years Ended December 31, 2017 2016 2015 (In thousands) Other (expense) income, net $ (16,213 ) $ 60,650 $ 36,938 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, expense of $15.4 million related to the extinguishment of the Match Group 6.75% Senior Notes and repricing of the Match Group Term Loan, expense of $13.0 million related to a mark-to-market adjustment 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 and expense of $1.2 million related to the write-off of deferred financing costs associated with the repayment of the 4.875% Senior Notes, partially offset by $34.9 million in gains related to the sales of certain investments and interest income of $11.4 million . Other income, net in 2016 includes gains of $37.5 million and $12.0 million related to the sale of ShoeBuy and PriceRunner, respectively, $34.4 million in net foreign currency exchange gains due to strengthening of the dollar relative to the British Pound and Euro, interest income of $5.1 million and a $3.6 million gain related to the sale of marketable equity securities, partially offset by a non-cash charge of $12.1 million 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 Match Group Term Loan, $10.7 million in other-than-temporary impairment charges related to certain investments, a loss of $3.8 million related to the sale of ASKfm, a $3.6 million loss on the 4.75% and 4.875% Senior Note redemptions and repurchases and an expense of $2.5 million related to a mark-to-market adjustment pertaining to a subsidiary denominated equity award held by a non-employee. Other income, net in 2015 included a gain of $34.3 million from a real estate transaction, $5.4 million in net foreign currency exchange gains due to the strengthening of the dollar relative to the Euro and $4.3 million in interest income, partially offset by $6.7 million in other-than-temporary impairment charges related to certain investments and an expense of $2.3 million related to a mark-to-market adjustment 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, 2017
Business Combinations [Abstract]
TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION	BUSINESS COMBINATION On September 29, 2017, the Company completed the combination of the businesses in the Company's HomeAdvisor segment and Angie's List under a new publicly traded company called ANGI Homeservices. Through the Combination, ANGI Homeservices acquired 100% of the common stock of Angie's List on September 29, 2017 for a total purchase price valued at $781.4 million . Angie’s List is a nationwide marketplace for local services where consumers can research, hire, rate and review the providers of these services. Ratings and reviews assist members in identifying and hiring a provider for their local service needs. Angie’s List's services are provided in markets located across the continental United States. 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. 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 $78.0 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 vested equity awards, which were converted into ANGI Homeservices' equity awards, and the acceleration of previously issued Angie's List equity awards held by employees terminated 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 . December 31, 2017 2016 (In thousands) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to IAC shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to IAC shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to IAC shareholders $ 4.27 $ (1.79 ) TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION ANGI Homeservices segment During the year ended December 31, 2017 , the Company incurred $44.1 million in costs related to the Combination (including severance, retention, transaction and integration related costs) as well as deferred revenue write-offs of $7.8 million . The Company also incurred $122.1 million in stock-based compensation expense during 2017 related to the modification of previously issued HomeAdvisor vested and unvested equity 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. See " Note 4—Business Combination " for additional information on the Combination. A summary of the costs incurred, payments made and the related accrual for ANGI Homeservices at December 31, 2017 is presented below. Year Ended December 31, 2017 (In thousands) Transaction and integration related costs $ 44,101 Stock-based compensation expense 122,066 Total $ 166,167 December 31, 2017 (In thousands) Charges incurred $ 44,101 Payments made (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, 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	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 and for the years ended December 31, 2017 , 2016 and 2015 for: IAC, on a stand-alone 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, 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 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 2,076,004 554,998 — (2,631,002 ) — Other non-current assets 170,073 87,306 79,688 (132,435 ) 204,632 Total assets $ 2,888,712 $ 2,114,868 $ 4,296,370 $ (3,432,140 ) $ 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 388,933 — 279,770 (668,703 ) — Other long-term liabilities 511 18,613 186,610 (132,435 ) 73,299 Redeemable noncontrolling interests — — 42,867 — 42,867 IAC shareholders' equity 2,430,028 1,976,131 654,871 (2,631,002 ) 2,430,028 Noncontrolling interests — — 516,795 — 516,795 Total liabilities and shareholders' equity $ 2,888,712 $ 2,114,868 $ 4,296,370 $ (3,432,140 ) $ 5,867,810 Balance sheet at December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 553,643 $ — $ 775,544 $ — $ 1,329,187 Marketable securities 89,342 — — — 89,342 Accounts receivable, net of allowance — 77,335 142,803 — 220,138 Other current assets 71,152 48,349 84,567 — 204,068 Intercompany receivables — 565,013 1,209,788 (1,774,801 ) — Property and equipment, net of accumulated depreciation and amortization 4,350 199,343 102,555 — 306,248 Goodwill — 412,010 1,512,042 — 1,924,052 Intangible assets, net of accumulated amortization — 83,179 272,272 — 355,451 Investment in subsidiaries 3,659,570 498,054 — (4,157,624 ) — Other non-current assets 52,228 118,624 162,008 (115,473 ) 217,387 Total assets $ 4,430,285 $ 2,001,907 $ 4,261,579 $ (6,047,898 ) $ 4,645,873 Current portion of long-term debt $ 20,000 $ — $ — $ — $ 20,000 Accounts payable, trade 2,697 29,867 30,299 — 62,863 Other current liabilities 42,160 84,827 503,538 — 630,525 Long-term debt, net 405,991 — 1,176,493 — 1,582,484 Income taxes payable — 3,470 30,274 (216 ) 33,528 Intercompany liabilities 1,774,801 — — (1,774,801 ) — Other long-term liabilities 315,414 21,002 51,817 (115,257 ) 272,976 Redeemable noncontrolling interests — — 32,827 — 32,827 IAC shareholders' equity 1,869,222 1,862,741 2,294,883 (4,157,624 ) 1,869,222 Noncontrolling interests — — 141,448 — 141,448 Total liabilities and shareholders' equity $ 4,430,285 $ 2,001,907 $ 4,261,579 $ (6,047,898 ) $ 4,645,873 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 425,675 20,755 — (446,430 ) — Interest expense (20,339 ) — (84,956 ) — (105,295 ) Other (expense) income, net (39,207 ) 28,434 (5,440 ) — (16,213 ) Earnings before income taxes 260,497 140,920 111,971 (446,430 ) 66,958 Income tax benefit (provision) 44,427 (119,957 ) 366,580 — 291,050 Net earnings 304,924 20,963 478,551 (446,430 ) 358,008 Net earnings attributable to noncontrolling interests — — (53,084 ) — (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 $ 20,963 $ 425,467 $ (446,430 ) $ 304,924 Comprehensive income attributable to IAC shareholders $ 367,370 $ 7,629 $ 504,558 $ (512,187 ) $ 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 operations for the year ended December 31, 2015: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 1,355,222 $ 1,876,305 $ (594 ) $ 3,230,933 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 720 341,351 436,649 (559 ) 778,161 Selling and marketing expense 3,210 624,979 720,172 (68 ) 1,348,293 General and administrative expense 93,090 94,896 324,036 33 512,055 Product development expense 4,311 73,500 118,812 — 196,623 Depreciation 1,918 23,912 36,375 — 62,205 Amortization of intangibles — 102,622 37,330 — 139,952 Goodwill impairment — 14,056 — — 14,056 Total operating costs and expenses 103,249 1,275,316 1,673,374 (594 ) 3,051,345 Operating (loss) income (103,249 ) 79,906 202,931 — 179,588 Equity in earnings of unconsolidated affiliates 215,080 17,353 — (232,433 ) — Interest expense (49,405 ) (6,130 ) (18,101 ) — (73,636 ) Other (expense) income, net (3,172 ) 27,810 12,300 — 36,938 Earnings before income taxes 59,254 118,939 197,130 (232,433 ) 142,890 Income tax benefit (provision) 60,218 (42,072 ) (47,662 ) — (29,516 ) Net earnings 119,472 76,867 149,468 (232,433 ) 113,374 Net loss attributable to noncontrolling interests — — 6,098 — 6,098 Net earnings attributable to IAC shareholders $ 119,472 $ 76,867 $ 155,566 $ (232,433 ) $ 119,472 Comprehensive income attributable to IAC shareholders $ 55,069 $ 73,970 $ 89,158 $ (163,128 ) $ 55,069 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 $ (61,002 ) $ 131,581 $ 346,111 $ 416,690 Cash flows from investing activities: Acquisitions, net of cash acquired — (2,550 ) (146,544 ) (149,094 ) Capital expenditures (337 ) (1,050 ) (74,136 ) (75,523 ) Proceeds from maturities and sales of marketable debt securities 114,350 — — 114,350 Purchases of marketable debt securities (29,891 ) — — (29,891 ) Purchases of investments — — (9,106 ) (9,106 ) Net proceeds from the sale of businesses and investments 1,266 — 184,512 185,778 Other, net — 1,944 1,050 2,994 Net cash provided by (used in) investing activities 85,388 (1,656 ) (44,224 ) 39,508 Cash flows from financing activities: Proceeds from issuance of IAC debt — — 517,500 517,500 Principal payments on 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 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (93,832 ) — — (93,832 ) Proceeds from the exercise of Match Group stock options — — 59,442 59,442 Withholding taxes paid on behalf of Match Group employees on net settled stock-based awards — — (254,210 ) (254,210 ) Proceeds from the exercise of ANGI Homeservices stock options — — 1,653 1,653 Withholding taxes paid on behalf of ANGI employees on net settled stock-based awards — — (10,113 ) (10,113 ) 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 ) Funds returned from escrow for MyHammer tender offer — — 10,604 10,604 Decrease in restricted cash related to bond redemptions 20,141 — — 20,141 Intercompany 424,816 (129,925 ) (294,891 ) — Other, net 251 — (5,251 ) (5,000 ) Net cash provided by (used in) financing activities 7,535 (129,925 ) (43,734 ) (166,124 ) Total cash provided 31,921 — 258,153 290,074 Effect of exchange rate changes on cash and cash equivalents 75 — 11,473 11,548 Net increase in cash and cash equivalents 31,996 — 269,626 301,622 Cash and cash equivalents at beginning of period 553,643 — 775,544 1,329,187 Cash and cash equivalents at end of period $ 585,639 $ — $ 1,045,170 $ 1,630,809 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 ) $ 128,473 $ 278,354 $ — $ 344,141 Cash flows from investing activities: Acquisitions, net of cash acquired — — (18,403 ) — (18,403 ) Capital expenditures (479 ) (5,762 ) (71,798 ) — (78,039 ) Investments in time deposits — — (87,500 ) — (87,500 ) Proceeds from maturities of time deposits — — 87,500 — 87,500 Proceeds from maturities and sales of marketable debt securities 252,369 — — — 252,369 Purchases of marketable debt securities (313,943 ) — — — (313,943 ) Purchases of investments — — (12,565 ) — (12,565 ) Net proceeds from the sale of businesses and investments 73,843 1,779 96,606 — 172,228 Intercompany (155,104 ) — — 155,104 — Other, net 126 910 10,179 — 11,215 Net cash (used in) provided by investing activities (143,188 ) (3,073 ) 4,019 155,104 12,862 Cash flows from financing activities: Principal payments on 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 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (26,716 ) — — — (26,716 ) Proceeds from the exercise of Match Group stock options — — 39,378 — 39,378 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 ) Funds held in escrow for MyHammer tender offer — — (10,548 ) — (10,548 ) Intercompany 122,965 (122,965 ) 155,104 (155,104 ) — Increase in restricted cash related to bond redemptions (141 ) — — — (141 ) Other, net (313 ) (2,084 ) (308 ) — (2,705 ) Net cash (used in) provided by financing activities (315,141 ) (125,400 ) 92,816 (155,104 ) (502,829 ) Total cash (used) provided (521,015 ) — 375,189 — (145,826 ) Effect of exchange rate changes on cash and cash equivalents — — (6,434 ) — (6,434 ) Net (decrease) increase in cash and cash equivalents (521,015 ) — 368,755 — (152,260 ) Cash and cash equivalents at beginning of period 1,074,658 — 406,789 — 1,481,447 Cash and cash equivalents at end of period $ 553,643 $ — $ 775,544 $ — $ 1,329,187 Statement of cash flows for the year ended December 31, 2015: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (121,331 ) $ 242,554 $ 284,448 $ 405,671 Cash flows from investing activities: Acquisitions, net of cash acquired — (6,078 ) (611,324 ) (617,402 ) Capital expenditures (1,332 ) (13,198 ) (47,519 ) (62,049 ) Proceeds from maturities and sales of marketable debt securities 218,462 — — 218,462 Purchases of marketable debt securities (93,134 ) — — (93,134 ) Purchases of investments (6,978 ) — (27,492 ) (34,470 ) Net proceeds from the sale of businesses and investments 1,277 — 8,136 9,413 Other, net 3,613 385 (7,539 ) (3,541 ) Net cash provided by (used in) investing activities 121,908 (18,891 ) (685,738 ) (582,721 ) Cash flows from financing activities: Principal payment on IAC debt — (80,000 ) — (80,000 ) Proceeds from issuance of Match Group debt — — 788,000 788,000 Debt issuance costs (1,876 ) — (17,174 ) (19,050 ) Fees and expenses related to note exchange — — (6,954 ) (6,954 ) Proceeds from Match Group initial public offering, net of fees and expenses — — 428,789 428,789 Purchase of IAC treasury stock (200,000 ) — — (200,000 ) Dividends (113,196 ) — — (113,196 ) Proceeds from the exercise of IAC stock options 27,325 — — 27,325 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (65,743 ) — — (65,743 ) Purchase of Match Group stock-based awards — — (23,431 ) (23,431 ) Purchase of noncontrolling interests — — (32,207 ) (32,207 ) Acquisition-related contingent consideration payments — (240 ) (5,510 ) (5,750 ) Increase in restricted cash related to bond redemptions (20,000 ) — — (20,000 ) Intercompany 684,716 (143,423 ) (541,293 ) — Other, net 166 — 441 607 Net cash provided by (used in) financing activities 311,392 (223,663 ) 590,661 678,390 Total cash provided 311,969 — 189,371 501,340 Effect of exchange rate changes on cash and cash equivalents — — (10,298 ) (10,298 ) Net increase in cash and cash equivalents 311,969 — 179,073 491,042 Cash and cash equivalents at beginning of period 762,689 — 227,716 990,405 Cash and cash equivalents at end of period $ 1,074,658 $ — $ 406,789 $ 1,481,447

QUARTERLY RESULTS (UNAUDITED)

QUARTERLY RESULTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS (UNAUDITED)	QUARTERLY RESULTS (UNAUDITED) Quarter Ended March 31 Quarter Ended June 30 Quarter Ended September 30 (a) (c) Quarter Ended December 31 (b) (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 (e) $ 0.34 $ 0.84 $ 2.22 $ 0.40 Diluted earnings per share (e) $ 0.29 $ 0.70 $ 1.79 $ 0.37 Quarter Ended March 31 (d) Quarter Ended June 30 (e) Quarter Ended September 30 Quarter Ended December 31 (d) (In thousands, except per share data) Year Ended December 31, 2016 Revenue $ 819,179 $ 745,439 $ 764,102 $ 811,162 Cost of revenue 193,734 170,397 179,131 212,468 Operating income (loss) 21,417 (252,446 ) 85,584 112,820 Net earnings (loss) 7,934 (190,542 ) 52,340 114,117 Net earnings (loss) attributable to IAC shareholders 8,282 (194,775 ) 43,162 102,051 Per share information attributable to IAC shareholders: Basic earnings (loss) per share (e) $ 0.10 $ (2.45 ) $ 0.54 $ 1.29 Diluted earnings (loss) per share (e) $ 0.09 $ (2.45 ) $ 0.49 $ 1.18 _______________________________________________________________________________ (a) The third quarter of 2017 includes after-tax stock-based compensation expense of $60.9 million related primarily 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. (b) The fourth quarter of 2017 includes after-tax stock-based compensation expense of $15.8 million related primarily 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). (c) The third quarter of 2017 includes 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. (d) The first quarter and fourth quarter of 2016 include after-tax gains of $11.9 million and $37.5 million related to the sale of PriceRunner and ShoeBuy, respectively. (e) The second quarter of 2016 includes after-tax impairment charges related to goodwill and indefinite-lived intangible assets of $183.5 million and $7.2 million , respectively. (f) 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.

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2017
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) 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 (b) 6,284 (c) — 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 ) (e) (1,475 ) (f) — 88,170 Other reserves 2,801 2,822 2015 Allowance for doubtful accounts and revenue reserves $ 12,437 $ 16,648 (a) $ (536 ) $ (12,021 ) (d) $ 16,528 Sales returns accrual 1,119 17,569 — (17,860 ) 828 Deferred tax valuation allowance 98,350 (6,072 ) (g) (1,796 ) (h) — 90,482 Other reserves 2,204 2,801 _________________________________________________________ (a) Additions to the allowance for doubtful accounts are charged to expense. Additions to the revenue reserves are charged against revenue. (b) Amount is due primarily to the establishment of foreign NOLs related to a recent acquisition. (c) Amount is primarily related to acquired state NOLs, acquired foreign tax credits and currency translation adjustments on foreign NOLs. (d) Write-off of fully reserved accounts receivable. (e) 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. (f) 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. (g) Amount is primarily related to the release of a valuation allowance on the other-than-temporary impairment charges for certain cost method investments, partially offset by an increase in federal, foreign and state net operating and capital losses. (h) Amount is primarily related to a net reduction in 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 ACCOUN32

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	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	Basis of Consolidation and Accounting for Investments 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. 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. Investments in the common stock or in-substance common stock of entities in which the Company does not have the ability to exercise significant influence over the operating and financial matters of the investee are accounted for using the cost method. Investments in companies that IAC does not control, which are not in the form of common stock or in-substance common stock, are also accounted for using the cost method. The Company evaluates each cost and equity method investment for impairment on a quarterly basis and recognizes an impairment loss if a decline in value is determined to be other-than-temporary. Such impairment evaluations include, but are not limited to: the current business environment, including competition; going concern considerations such as financial condition, the rate at which the investee utilizes cash and the investee's ability to obtain additional financing to achieve its business plan; the need for changes to the investee's existing business model due to changing business and regulatory environments and its ability to successfully implement necessary changes; and comparable valuations. If the Company has not identified events or changes in circumstances that may have a significant adverse effect on the fair value of a cost method investment, then the fair value of such cost method investment is not estimated, as it is impracticable to do so.
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 securities and long-term investments; 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; the liabilities for uncertain tax positions; 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 recognizes revenue when persuasive evidence of an arrangement exists, services are rendered or merchandise is delivered to customers, the fee or price charged is fixed or determinable and collectability is reasonably assured. Deferred revenue is recorded when payments are received, or contractually due, in advance of the Company's rendering of services, availability of media content (films, television, or digital content) for broadcast or exhibition or delivery of merchandise. Match Group Match Group's 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 using a credit card or through mobile app stores, and, subject to certain conditions identified in our terms and conditions, all purchases are final and nonrefundable. Fees collected, or contractually due, in advance for subscriptions are deferred and recognized using the straight-line method over the terms of the applicable subscription period, which primarily range from one to six months, and corresponding mobile app store fees incurred on such transactions, if any, are deferred and expensed over the same period. Deferred revenue at Match Group is $198.3 million and $161.1 million at December 31, 2017 and 2016 , respectively. Revenue is also earned from online advertising, the purchase of à la carte features and offline events. Online advertising revenue is recognized every time an advertisement is displayed. Revenue from the purchase of à la carte features is recognized based on usage. Revenue and the related expenses associated with offline events are recognized when each event occurs. ANGI Homeservices ANGI Homeservices revenue is primarily derived from (i) consumer connection revenue, which comprises fees paid by service professionals for consumer matches (regardless of whether the professional ultimately provides the requested service), and (ii) membership subscriptions fees paid by service professionals. Consumer connection revenue varies based upon certain factors including the service requested, type of match (such as Instant Booking, Instant Connect, same day service or next day service) and geographic location of service. Effective with the Combination, revenue is also derived from Angie's List (i) sales of time-based advertising to service professionals and (ii) membership subscription fees from consumers. ANGI Homeservices consumer connection revenue is generated and recognized when an in‑network service professional is delivered a consumer match. Membership subscription revenue is generated through subscription sales to service professionals and is deferred and recognized over the term of the applicable membership. Membership agreements can be one month, three months , or one year. 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. These contracts include an early termination penalty. Angie's List revenue from the sale of website, mobile and call center advertising is recognized ratably over the period during which the advertisements run. Revenue from the sale of advertising in the Angie’s List Magazine is recognized in the period in which the publication is published and distributed. Angie's List prepaid consumer membership subscription fees are recognized as revenue ratably over the term of the associated subscription, which is typically one year. Deferred revenue at ANGI Homeservices is $64.1 million and $18.8 million at December 31, 2017 and 2016 , respectively. The balance at December 31, 2017 includes Angie's List deferred revenue of $37.7 million . Video Revenue of businesses included in this segment is generated primarily through subscriptions, media production and distribution, and advertising. Production revenue is recognized when the production is available for the customer to broadcast or exhibit, subscription fee revenue is recognized over the terms of the applicable subscriptions, which are one month or one year, and advertising revenue is recognized when an ad is displayed or over the period earned. Deferred revenue at Vimeo is $49.4 million and $36.7 million at December 31, 2017 and 2016 , respectively. Deferred revenue at Electus totals $12.8 million and $23.1 million at December 31, 2017 and 2016 , respectively. Applications Substantially all of Applications' revenue 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 Applications businesses are supplied to us by Google Inc. ("Google") pursuant to our services agreement with Google. Pursuant to this agreement, those of our Applications 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 Applications 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. We recognize 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 significantly lesser extent, Applications' revenue also consists of fees related to subscription downloadable applications, which are recognized over the terms of the applicable subscriptions, primarily one to two years, and fees related to paid mobile downloadable applications and display advertisements, which are recognized at the time of the sale and when the ad is displayed, respectively. Deferred revenue at Applications is $23.6 million and $26.1 million at December 31, 2017 and 2016 , respectively. Publishing Publishing's revenue consists principally of advertising revenue, which is generated primarily through the display of paid listings in response to search queries, display advertisements (sold directly and through programmatic ad sales) and fees related to paid mobile downloadable applications. The substantial majority of the paid listings that our Publishing businesses display are supplied to us by Google in the manner and pursuant to the services agreement with Google, which is described above under " Applications. " Other The Princeton Review's revenue consisted primarily of fees received directly from students for in-person and online test preparation classes, access to online test preparation materials and individual tutoring services. Fees from classes and access to online materials were recognized over the period of the course and the period of the online access, respectively. Tutoring fees were recognized based on usage. ShoeBuy's revenue consisted of merchandise sales, reduced by incentive discounts and sales returns, and was recognized when delivery to the customer had occurred. Delivery was considered to have occurred when the customer took title and assumed the risks and rewards of ownership, which was on the date of shipment. Accruals for returned merchandise were based on historical experience. Shipping and handling fees billed to customers was recorded as revenue. The costs associated with shipping goods to customers were recorded as cost of revenue. PriceRunner's revenue consisted principally of advertising revenue that, depending on the terms of the arrangement, was recognized when a user clicked on an ad, or when a user clicked-through on the ad and took a specified action on the destination site.
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, commercial paper rated A1/P1 or better and treasury discount notes. Internationally, cash equivalents primarily consist of AAA rated government money market funds and time deposits.
Marketable Securities	Marketable Securities At December 31, 2017 , marketable securities consist of commercial paper rated A1+/P1. 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. The Company also invests in marketable equity securities as part of its investment strategy. All marketable securities are classified as available-for-sale and are reported at fair value. The unrealized gains and losses on marketable securities, net of tax, are included in accumulated other comprehensive income as a separate component of shareholders' equity. The specific-identification method is used to determine the cost of securities sold and the amount of unrealized gains and losses reclassified out of accumulated other comprehensive income into earnings. The Company employs a methodology that considers available evidence in evaluating potential other-than-temporary impairments of its investments. Investments are considered to be impaired when a decline in fair value below the amortized cost basis is determined to be other-than-temporary. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the amortized cost basis, the financial condition and near-term prospects of the issuer, and whether it is not more likely than not that the Company will be required to sell the security before the recovery of the amortized cost basis, which may be maturity. If a decline in fair value is determined to be other-than-temporary, an impairment charge is recorded in current earnings and a new cost basis in the investment is established.
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. For the years ended December 31, 2017 , 2016 and 2015 , revenue from Google represents 22% , 26% and 40% respectively, of the Company's consolidated revenue. The services agreement became effective on April 1, 2016, following the expiration of the previous services agreement, and expires on March 31, 2020; however, the Company may choose to terminate the agreement effective March 31, 2019. 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. For the years ended December 31, 2017 , 2016 and 2015 , revenue earned from Google was $740.7 million , $824.4 million and $1.3 billion , respectively. This revenue is earned by the businesses comprising the Applications and Publishing segments. For the years ended December 31, 2017 , 2016 and 2015 , revenue earned from Google represents 83% , 87% and 94% of Applications revenue and 71% , 73% and 83% of Publishing revenue, respectively. Accounts receivable related to revenue earned from Google totaled $72.4 million and $65.8 million at December 31, 2017 and 2016 , respectively. 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.
Accounts Receivable, net of allowance for doubtful accounts and revenue reserves	Accounts Receivable, net of allowance for doubtful accounts and revenue reserves Accounts receivable are stated at amounts due from customers, net of an allowance for doubtful accounts and revenue reserves. Accounts receivable outstanding longer than the contractual payment terms are considered past due. The Company determines its allowance by considering a number of factors, including the length of time accounts receivable are past due, the Company's previous loss history, the specific customer's ability to pay its obligation to the Company and the condition of the general economy and the customer's industry. The Company writes off accounts receivable when they become uncollectible. The Company also maintains allowances to reserve for potential credits issued to customers or other revenue adjustments. The amounts of these reserves are based, in part, on historical experience.
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 detailed 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 are 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 loss equal to the excess is recorded. For the Company's annual goodwill test at October 1, 2017, a qualitative assessment of the Match Group, ANGI Homeservices, Vimeo and Applications 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 is described below: • Match Group's October 1, 2017 market capitalization of $6.3 billion exceeded its carrying value by more than 1100% and Match Group's strong operating performance. • ANGI Homeservices' October 1, 2017 market capitalization of $5.9 billion exceeded its carrying value by more than 450% and ANGI Homeservices' strong operating performance. • The Company performed valuations of the Vimeo and Applications reporting units during 2017. 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, 2017. The fair value of each of these businesses was in excess of its October 1, 2017 carrying value. For the Company's annual goodwill test at October 1, 2017, the Company quantitatively tested the Daily Burn and Electus reporting units. The Company's quantitative test indicated that the fair value of each of these reporting units is in excess of its respective carrying value; therefore, the goodwill of these reporting units is not impaired. The Company's Publishing reporting unit has no goodwill. The aggregate goodwill balance for the reporting units for which the most recent estimate of fair value is less than 120% of their carrying values is approximately $450 million . The fair value of the Company's reporting units 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 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 determining the fair value of the Company's reporting units ranged from 12.5% to 17.5% in 2017 and 10% to 17.5% in 2016. 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. In 2017, the Company did not quantitatively assess the Angie's List indefinite-lived intangible assets acquired through the Combination given the proximity of the September 29, 2017 transaction date to the October 1, 2017 annual test date. The Company determines the fair values of its indefinite-lived intangible assets using avoided royalty DCF analyses. Significant judgments inherent in these analyses 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 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 11% to 16% in both 2017 and 2016, and the royalty rates used ranged from 2% and 7% in both 2017 and 2016. The 2017 annual assessment 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 impairment charges related to the entire $275.4 million balance of the Publishing reporting unit goodwill and $11.6 million related to certain Publishing indefinite-lived intangible assets. The goodwill impairment charge at Publishing was driven by the impact from the new 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 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 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 Publishing reporting unit. To determine a peer group of companies for 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 charge 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. In 2015, the Company identified and recorded impairment charges of $88.0 million related to certain indefinite-lived intangible assets at the Publishing segment and $14.1 million at the Other segment related to goodwill at ShoeBuy. The indefinite-lived intangible asset impairment charge at Publishing related to certain trade names of certain Ask & Other direct marketing brands, including Ask Media Group. The impairment charge reflected the impact of Google ecosystem changes that impacted our ability to market, the effect of the reduced revenue share on mobile under the terms of the services agreement with Google, and the shift in focus to higher margin businesses in Publishing's Premium Brands. The combined impact of these factors reduced the forecasted revenue and profits for these brands and the impairment charge reflected the resultant reduction in fair value. The goodwill impairment charge at ShoeBuy was due to increased investment and the seasonal effect of high inventory levels as of October 1, 2015. The Company's reporting units are consistent with its determination of its operating segments. 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 prices for identical assets and liabilities in active markets. • Level 2: Other inputs, which are observable directly or indirectly, such as quoted prices for similar assets or liabilities in active markets, quoted 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 8—Fair Value Measurements and 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, as well as cost and equity method investments, are adjusted to fair value only when an impairment charge 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) payments made to partners who distribute our Partnerships customized browser-based applications and who integrate our paid listings into their websites and (ii) fees related to the distribution and facilitation of in-app purchase of product features. 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 Consumer downloadable applications, offline marketing, which is primarily television advertising, and partner-related payments to those who direct traffic to the Match Group brands. Advertising expense is $1.1 billion , $1.0 billion and $1.2 billion for the years ended December 31, 2017 , 2016 and 2015 , 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 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 on deferred tax assets 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
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 (expense) income, net. See " Note 19—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. During the years ended December 31, 2017 , 2016 and 2015 , two , one and two of these arrangements, respectively, were exercised. 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, 2017 , 2016 and 2015 , the Company recorded adjustments of $6.3 million , $7.9 million and $23.2 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 not yet adopted by the Company In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers, which clarifies the principles for recognizing revenue and develops a common standard for all industries. ASU No. 2014-09 was subsequently amended during 2015, 2016 and 2017; these amendments provide further revenue recognition guidance related to principal versus agent considerations, performance obligations and licensing, narrow-scope improvements and practical expedients. ASU No. 2014-09 is a comprehensive revenue recognition standard that will supersede nearly all existing revenue recognition guidance under GAAP. The new standard provides a single principles-based, five-step model to be applied to all contracts with customers. This five-step model includes (1) identifying the contract(s) with the customer, (2) identifying the performance obligations in the contract, (3) determining the transaction price, (4) allocating the transaction price to the performance obligations in the contract and (5) recognizing revenue when each performance obligation is satisfied. More specifically, revenue will be recognized when promised goods or services are transferred to the customer in an amount that reflects the consideration expected in exchange for those goods or services. ASU No. 2014-09 is effective for interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted for interim and annual reporting periods beginning after December 15, 2016. Upon adoption, ASU No. 2014-09 may either be applied retrospectively to each prior period presented or using the modified retrospective approach with the cumulative effect recognized as of the date of initial application. The Company’s evaluation of the impact of the adoption of ASU No. 2014-09 on its consolidated financial statements is substantially complete. The principal remaining work is a confirmation of the calculation of the cumulative effect of ASU No. 2014-09 as of January 1, 2018, which will be completed during the financial close process for the first quarter of 2018. The adoption of ASU No. 2014-09 is not expected to have a material effect on the Company's consolidated financial statements. The Company has reached the following determinations. • The Company has adopted ASU No. 2014-09 using the modified retrospective approach effective January 1, 2018. Therefore, the cumulative effect of adoption will be reflected as an adjustment to beginning retained earnings in the Form 10-Q for the period ending March 31, 2018. • Within ANGI Homeservices, the effect of the adoption of ASU No. 2014-09 on HomeAdvisor will be that sales commissions, which represent the incremental direct costs of obtaining a service professional contract, will be capitalized and amortized over the average life of a service professional. These costs were expensed as incurred prior to January 1, 2018. Prior to the Combination, Angie's List capitalized sales commissions and amortized the cost over the term of the applicable advertising contract. Following the Combination, Angie's List accounting policies were conformed to the HomeAdvisor's accounting policies and these costs are expensed as incurred. Following the adoption of ASU No. 2014-09, these costs will be capitalized and amortized over the average life of a service professional. • Within Applications, the primary effect of the adoption of ASU No. 2014-09 will be to accelerate the recognition of the portion of the revenue of certain desktop applications sold by SlimWare that qualify as functional intellectual property under ASU No. 2014-09. This revenue is currently deferred and recognized over the applicable subscription term. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments, which updates certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Under ASU No. 2016-01, certain equity investments will be measured at fair value with changes recognized in net income. ASU No. 2016-01 is effective for reporting periods beginning after December 15, 2017. The Company will adopt ASU No. 2016-01 effective January 1, 2018 and its adoption will not have a material effect on the consolidated financial statements upon adoption. The adoption of ASU No. 2016-01 may increase the volatility of our results of operations as a result of the remeasurement of our cost method investments. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which supersedes existing guidance on accounting for leases in "Leases (Topic 840)" 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; early adoption is permitted. The provisions of ASU No. 2016-02 are to be applied using a modified retrospective approach. The Company will adopt ASU No. 2016-02 effective January 1, 2019. The Company is not a lessor and 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 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 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 Company's outstanding debt, or the debt of our Match Group and ANGI Homeservices subsidiaries, or our credit agreement or the credit agreement of Match Group because, in each circumstance, the leverage calculations are not affected by the 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 package to assist in the determination of the right of use asset and related liability as of January 1, 2019 and to provide the required information following the adoption; • the Company has prepared summaries of its leases for input into the software package; • 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 controls related to the new standard. The Company does not expect to have a preliminary estimate of the right of use asset and related liability as of the adoption date until the third quarter of 2018. Accounting Pronouncements adopted by the Company In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting , which provides guidance about the changes to the terms and conditions of a share-based payment award that require an entity to apply modification accounting in "Stock Compensation (Topic 718)." The provisions of ASU No. 2017-09 are effective for reporting periods beginning after December 15, 2017; early adoption is permitted. The provisions of ASU No. 2017-09 are to be applied prospectively to an award modified on or after the adoption date. The Company early adopted the provisions of ASU No. 2017-09 during the third quarter of 2017 and the adoption of this standard update did not have a material impact on its consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies how cash receipts and cash payments in certain transactions are presented and classified on the statement of cash flows. The provisions of ASU No. 2016-15 are effective for reporting periods beginning after December 15, 2017, including interim periods, and will require adoption on a retrospective basis unless it is impracticable to apply, in which case we would be required to apply the amendments prospectively as of the earliest date practicable; early adoption is permitted. Upon adoption, cash payments made soon after the acquisition date of a business to settle a contingent consideration liability are classified as cash outflows for investing activities. Cash payments which are not made soon after the acquisition date of a business to settle a contingent consideration liability are separated and classified as cash outflows for financing activities up to the amount of the contingent consideration liability recognized at the acquisition date and as cash outflows from operating activities for any excess. The Company early adopted the provisions of ASU No. 2016-15 on January 1, 2017. As a result, $11.1 million of an acquisition-related contingent consideration payment of $15.0 million , which was in excess of the liability initially recognized at the acquisition date, has been classified as a cash outflow within net cash provided by operating activities in the accompanying consolidated statement of cash flows for the year ended December 31, 2017 . In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The Company adopted the provisions of ASU No. 2016-09 on January 1, 2017. Excess tax benefits or deficiencies related to equity awards to employees upon the exercise of stock options and the vesting of restricted stock units after January 1, 2017 are (i) reflected in the consolidated statement of operations as a component of the provision for income taxes, rather than recognized in equity (adopted on a prospective basis), and (ii) reflected as operating, rather than financing, cash flows in our consolidated statement of cash flows (adopted on a retrospective basis). Upon adoption, the calculation of fully diluted shares excludes excess tax benefits from the assumed proceeds in applying the treasury stock method; previously such benefits were included in the calculation. This change increased fully diluted shares by approximately 2.4 million shares for the year ended December 31, 2017 . The Company continues to account for forfeitures using an estimated forfeiture rate. In January 2017, the FASB issued ASU No. 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , which is intended to simplify the accounting for goodwill impairment. The guidance eliminates the requirement to calculate the implied fair value of goodwill under the two-step impairment test to measure a goodwill impairment charge. The Company early adopted the provisions of ASU No. 2017-04 on January 1, 2017 and the adoption of this standard update did not have a material impact on its consolidated financial statements.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation.

SUMMARY OF SIGNIFICANT ACCOUN33

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 252,511 $ 247,563 Computer equipment and capitalized software 218,529 275,455 Furniture and other equipment 88,930 94,555 Projects in progress 19,094 13,048 Land 7,917 5,117 586,981 635,738 Accumulated depreciation and amortization (271,811 ) (329,490 ) Property and equipment, net of accumulated depreciation and amortization $ 315,170 $ 306,248

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 (In thousands) U.S. $ (52,606 ) $ (248,433 ) $ 79,656 Foreign 119,564 167,348 63,234 Total $ 66,958 $ (81,085 ) $ 142,890
Schedule of Components of Income Tax Expense (Benefit)	The components of the (benefit) provision for income taxes are as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Current income tax (benefit) provision: Federal $ (31,844 ) $ 23,343 $ 67,505 State 1,964 3,662 7,785 Foreign 24,108 27,242 14,012 Current income tax (benefit) provision (5,772 ) 54,247 89,302 Deferred income tax (benefit) provision: Federal (255,477 ) (100,798 ) (50,254 ) State (28,364 ) (9,518 ) (3,727 ) Foreign (1,437 ) (8,865 ) (5,805 ) Deferred income tax (benefit) provision (285,278 ) (119,181 ) (59,786 ) Income tax (benefit) provision $ (291,050 ) $ (64,934 ) $ 29,516
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, 2017 and 2016 : December 31, 2017 2016 (In thousands) Income taxes receivable (payable): Other current assets $ 33,239 $ 41,352 Other non-current assets 1,949 1,615 Accrued expenses and other current liabilities (11,798 ) (5,788 ) Income taxes payable (25,624 ) (33,528 ) Net income taxes (payable) receivable $ (2,234 ) $ 3,651 Deferred tax assets (liabilities): Other non-current assets $ 66,321 $ 2,511 Deferred income taxes (35,070 ) (228,798 ) Net deferred tax assets (liabilities) $ 31,251 $ (226,287 )
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, 2017 2016 (In thousands) Deferred tax assets: Accrued expenses $ 22,234 $ 40,273 NOL carryforwards 292,812 63,948 Tax credit carryforwards 78,715 11,570 Stock-based compensation 77,976 87,914 Equity method investments 12,066 17,455 Intangible and other assets — 13,708 Other 30,265 30,044 Total deferred tax assets 514,068 264,912 Less valuation allowance (132,598 ) (88,170 ) Net deferred tax assets 381,470 176,742 Deferred tax liabilities: Investment in subsidiaries (247,167 ) (385,474 ) Intangible and other assets (87,811 ) — Other (15,241 ) (17,555 ) Total deferred tax liabilities (350,219 ) (403,029 ) Net deferred tax assets (liabilities) $ 31,251 $ (226,287 )
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the income tax (benefit) provision 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, 2017 2016 2015 (In thousands) Income tax (benefit) provision at the federal statutory rate of 35% $ 23,435 $ (28,446 ) $ 50,006 Transition tax 62,667 — — Stock-based compensation (358,901 ) 3,998 1,787 Foreign income taxed at a different statutory tax rate (14,725 ) (27,115 ) (10,382 ) State income taxes, net of effect of federal tax benefit 86 (3,880 ) 2,208 Realization of certain deferred tax assets (3,133 ) — (22,440 ) Non-taxable sale and non-deductible goodwill associated with ShoeBuy — (13,142 ) 4,920 Goodwill impairment of Publishing — 10,649 — Research credit (5,304 ) (2,231 ) (2,354 ) Non-deductible impairments for certain cost method investments 2,669 3,489 2,341 Deferred tax adjustment for enacted changes in tax laws and rates 705 (4,594 ) — Other, net 1,451 (3,662 ) 3,430 Income tax (benefit) provision $ (291,050 ) $ (64,934 ) $ 29,516
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, 2017 2016 2015 (In thousands) Balance at January 1 $ 38,372 $ 40,808 $ 30,386 Additions based on tax positions related to the current year 2,050 2,033 4,227 Additions for tax positions of prior years 1,994 2,676 14,467 Reductions for tax positions of prior years (3,761 ) (743 ) (1,556 ) Settlements — (5,107 ) — Expiration of applicable statutes of limitations (1,923 ) (1,295 ) (6,716 ) Balance at December 31 $ 36,732 $ 38,372 $ 40,808

BUSINESS COMBINATION (Tables)

BUSINESS COMBINATION (Tables)	12 Months Ended
	Dec. 31, 2017
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 for ANGI Homeservices at December 31, 2017 is presented below. Year Ended December 31, 2017 (In thousands) Transaction and integration related costs $ 44,101 Stock-based compensation expense 122,066 Total $ 166,167 December 31, 2017 (In thousands) Charges incurred $ 44,101 Payments made (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, 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	December 31, 2017 2016 (In thousands) Revenue $ 3,529,600 $ 3,429,105 Net earnings (loss) attributable to IAC shareholders $ 364,496 $ (143,133 ) Basic earnings (loss) per share attributable to IAC shareholders $ 4.55 $ (1.79 ) Diluted earnings (loss) per share attributable to IAC shareholders $ 4.27 $ (1.79 )

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Intangible Assets, Net	Goodwill and intangible assets, net are as follows: December 31, 2017 2016 (In thousands) Goodwill $ 2,559,066 $ 1,924,052 Intangible assets with indefinite lives 459,143 320,645 Intangible assets with definite lives, net of accumulated amortization 204,594 34,806 Total goodwill and intangible assets, net $ 3,222,803 $ 2,279,503
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, 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 Video 25,239 70,369 — — 95,608 Applications 447,242 — — — 447,242 Other 74,422 — (74,430 ) 8 — Total $ 1,924,052 $ 661,396 $ (74,430 ) $ 48,048 $ 2,559,066 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, 2016 : Balance at Additions Deductions Impairment Foreign Balance at (In thousands) Match Group $ 1,218,607 $ 603 $ (2,983 ) $ — $ (9,689 ) $ 1,206,538 ANGI Homeservices 150,251 21,985 — — (1,625 ) 170,611 Video 15,590 9,649 — — — 25,239 Applications 447,242 — — — — 447,242 Publishing 277,192 — (1,968 ) (275,367 ) 143 — Other 136,482 — (62,860 ) — 800 74,422 Total $ 2,245,364 $ 32,237 $ (67,811 ) $ (275,367 ) $ (10,371 ) $ 1,924,052
Schedule of Intangible Assets with Definite Lives	Intangible assets with indefinite lives are trade names and trademarks acquired in various acquisitions. During the second quarter of 2016, the Company changed the classification of certain intangibles from indefinite-lived to definite-lived at Publishing. At December 31, 2017 and 2016 , intangible assets with definite lives are as follows: December 31, 2017 Gross Accumulated Net Weighted-Average (In thousands) Contractor and service professional relationships and other $ 102,997 $ (13,252 ) $ 89,745 3.0 Technology 115,200 (37,357 ) 77,843 4.8 Customer lists and user base 23,468 (5,401 ) 18,067 2.2 Content 5,000 (3,973 ) 1,027 5.0 Trade names 16,986 (13,634 ) 3,352 2.6 Memberships 15,900 (1,340 ) 14,560 3.0 Total $ 279,551 $ (74,957 ) $ 204,594 3.7 December 31, 2016 Gross Accumulated Net Weighted-Average (In thousands) Contractor relationships and other $ 7,230 $ (2,612 ) $ 4,618 4.5 Technology 38,602 (27,667 ) 10,935 3.4 Customer lists and user base 12,485 (9,997 ) 2,488 3.7 Content 14,802 (8,965 ) 5,837 4.3 Trade names 63,855 (52,927 ) 10,928 1.8 Total $ 136,974 $ (102,168 ) $ 34,806 2.8
Schedule of Expected Amortization of Intangible Assets	At December 31, 2017 , 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) 2018 $ 72,395 2019 56,624 2020 44,438 2021 12,529 2022 10,650 Thereafter 7,958 Total $ 204,594

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2017
Marketable Securities [Abstract]
Schedule of Current Available-for-sale Marketable Securities	At December 31, 2017 , current available-for-sale marketable securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 4,995 $ — $ — $ 4,995 Total marketable securities $ 4,995 $ — $ — $ 4,995 At December 31, 2016 , current available-for-sale marketable securities are as follows: Amortized Gross Gross Fair Value (In thousands) Commercial paper $ 49,797 $ — $ — $ 49,797 Treasury discount notes 34,978 — (4 ) 34,974 Corporate debt securities 4,575 2 (6 ) 4,571 Total marketable securities $ 89,350 $ 2 $ (10 ) $ 89,342
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 securities and the related gross realized gains: December 31, 2017 2016 2015 (In thousands) Proceeds from maturities and sales of available-for-sale marketable securities $ 114,350 $ 279,485 $ 218,976 Gross realized gains — 3,556 443

LONG-TERM INVESTMENTS (Tables)

LONG-TERM INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Long-term Investments [Abstract]
Schedule of Long-term Investments	Long-term investments consist of: December 31, 2017 2016 (In thousands) Cost method investments $ 63,418 $ 116,133 Equity method investments 1,559 6,677 Total long-term investments $ 64,977 $ 122,810

FAIR VALUE MEASUREMENTS AND F39

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present the Company's financial instruments that are measured at fair value on a recurring basis: December 31, 2017 Quoted Market Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Measurements (In thousands) Assets: Cash equivalents: Money market funds $ 780,425 $ — $ — $ 780,425 Time deposits — 60,000 — 60,000 Treasury discount notes 100,457 — — 100,457 Commercial paper — 215,325 — 215,325 Certificates of deposit — 6,195 — 6,195 Marketable securities: Commercial paper — 4,995 — 4,995 Total $ 880,882 $ 286,515 $ — $ 1,167,397 Liabilities: Contingent consideration arrangements $ — $ — $ (2,647 ) $ (2,647 ) December 31, 2016 Quoted Market Significant Significant Total (In thousands) Assets: Cash equivalents: Money market funds $ 667,662 $ — $ — $ 667,662 Time deposits — 79,000 — 79,000 Treasury discount notes 24,991 — — 24,991 Commercial paper — 123,640 123,640 Marketable securities: Commercial paper — 49,797 49,797 Treasury discount notes 34,974 — — 34,974 Corporate debt securities — 4,571 — 4,571 Total $ 727,627 $ 257,008 $ — $ 984,635 Liabilities: Contingent consideration arrangements $ — $ — $ (33,871 ) $ (33,871 )
Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents the changes in the Company's financial instruments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3): For the Year Ended December 31, 2017 2016 Contingent Auction Rate Contingent Consideration Arrangements (In thousands) Balance at January 1 $ (33,871 ) $ 4,050 $ (33,873 ) Total net (losses) gains: Included in earnings: Fair value adjustments (5,801 ) — (2,555 ) Included in other comprehensive (loss) income (1,404 ) 5,950 (1,571 ) Fair value at date of acquisition — — (185 ) Settlements 38,429 — 2,180 Proceeds from sale — (10,000 ) — Other — — 2,133 Balance at December 31 $ (2,647 ) $ — $ (33,871 )
Schedule of Carrying Value and Fair Value of Financial Instruments	The following table presents the carrying value and the fair value of financial instruments measured at fair value only for disclosure purposes: December 31, 2017 December 31, 2016 Carrying Fair Carrying Fair (In thousands) Current portion of long-term debt $ (13,750 ) $ (13,802 ) $ (20,000 ) $ (20,311 ) Long-term debt, net (1,979,469 ) (2,168,108 ) (1,582,484 ) (1,657,861 )

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt consists of: December 31, 2017 2016 (In thousands) Match Group Debt: Match Group Term Loan due November 16, 2022 $ 425,000 $ 350,000 6.75% Senior Notes due December 15, 2022 (the "Match Group 6.75% Senior Notes"); interest payable each June 15 and December 15 — 445,172 6.375% Senior Notes due June 1, 2024 (the "Match Group 6.375% Senior Notes"); interest payable each June 1 and December 1 400,000 400,000 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 450,000 — Total Match Group long-term debt 1,275,000 1,195,172 Less: unamortized original issue discount and original issue premium, net 8,668 5,245 Less: unamortized debt issuance costs 13,636 13,434 Total Match Group debt, net 1,252,696 1,176,493 ANGI Homeservices Debt: ANGI Homeservices Term Loan due November 1, 2022 275,000 — Less: current portion of ANGI Homeservices long-term debt 13,750 — Less: unamortized debt issuance costs 2,938 — Total ANGI Homeservices debt 258,312 — IAC Debt: 0.875% Exchangeable Senior Notes due October 1, 2022 (the "Exchangeable Notes"); interest payable each April 1 and October 1, which commences on April 1, 2018 517,500 — 4.75% Senior Notes due December 15, 2022 (the "4.75% Senior Notes"); interest payable each June 15 and December 15 34,859 38,109 4.875% Senior Notes due November 30, 2018 (the "4.875% Senior Notes"); interest payable each May 30 and November 30 — 390,214 Total IAC long-term debt 552,359 428,323 Less: current portion of IAC long-term debt — 20,000 Less: unamortized original issue discount 67,158 — Less: unamortized debt issuance costs 16,740 2,332 Total IAC debt, net 468,461 405,991 Total long-term debt, net $ 1,979,469 $ 1,582,484
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	We may redeem the 4.75% Senior Notes at the redemption prices set forth below, together with accrued and unpaid interest thereon to the applicable redemption date, if redeemed 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 % Long-term debt maturities: Years Ending December 31, (In thousands) 2018 $ 13,750 2019 13,750 2020 13,750 2021 27,500 2022 1,183,609 2024 400,000 2027 450,000 Total 2,102,359 Less: current portion of long-term debt 13,750 Less: unamortized original issue discount 75,826 Less: unamortized debt issuance costs 33,314 Total long-term debt, net $ 1,979,469

ACCUMULATED OTHER COMPREHENSI41

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Dec. 31, 2017
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, 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 ) (a) (3,360 ) Net current period other comprehensive income (loss) 66,581 (4,026 ) 62,555 Balance at December 31 $ (103,568 ) $ — $ (103,568 ) _________________________ (a) Amount includes a tax benefit of $3.8 million . At December 31, 2017 , there was no tax benefit or provision on the accumulated other comprehensive loss. 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 ) (b) 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 ) _________________________ (b) Amount is net of a tax provision of $0.2 million . Year Ended December 31, 2015 Foreign Currency Translation Adjustment Unrealized (Losses) Gain On Available-For-Sale Securities Accumulated Other Comprehensive Loss (In thousands) Balance at January 1 $ (86,848 ) $ (852 ) $ (87,700 ) Other comprehensive (loss) income before reclassifications, net of tax provision of $0.6 million related to unrealized gains on available-for-sale securities (65,606 ) 3,537 (62,069 ) Amounts reclassified to earnings (2,191 ) (143 ) (c) (2,334 ) Net current period other comprehensive (loss) income (67,797 ) 3,394 (64,403 ) Balance at December 31 $ (154,645 ) $ 2,542 $ (152,103 ) _________________________ (c) Amount is net of a tax provision of $0.1 million .

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 Basic Diluted Basic Diluted Basic Diluted (In thousands, except per share data) Numerator: Net earnings (loss) $ 358,008 $ 358,008 $ (16,151 ) $ (16,151 ) $ 113,374 $ 113,374 Net (earnings) loss attributable to noncontrolling interests (53,084 ) (53,084 ) (25,129 ) (25,129 ) 6,098 6,098 Impact from public subsidiaries' dilutive securities (a) — (33,531 ) — — — (1,799 ) Net earnings (loss) attributable to IAC shareholders $ 304,924 $ 271,393 $ (41,280 ) $ (41,280 ) $ 119,472 $ 117,673 Denominator: Weighted average basic shares outstanding 80,089 80,089 80,045 80,045 82,944 82,944 Dilutive securities (b) (c) (d) (e) (f) (g) — 5,221 — — — 5,323 Denominator for earnings per share—weighted average shares (b) (c) (d) (e) (f) (g) 80,089 85,310 80,045 80,045 82,944 88,267 Earnings (loss) per share attributable to IAC shareholders: Earnings (loss) per share $ 3.81 $ 3.18 $ (0.52 ) $ (0.52 ) $ 1.44 $ 1.33 __________________________________________________________________ (a) The amount for the years ended December 31, 2017 and 2015 reflects the reduction in Match Group's earnings (after its IPO on November 24, 2015) attributable to IAC from the assumed exercise of Match Group dilutive securities under the if-converted method. For the year ended December 31, 2016 , the impact on earnings related to Match Group's dilutive securities under the if-converted method is excluded because it would have been anti-dilutive due to the Company's net loss. (b) Dilutive securities for the year ended December 31, 2017 , include the impact from the assumed exercise of ANGI Homeservices dilutive securities under the if-converted method, as it is more dilutive for IAC to settle certain ANGI Homeservices equity awards. The impact on earnings of ANGI Homeservices 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, conversion of the Company's Exchangeable Notes and vesting of restricted stock units ("RSUs"). For the years ended December 31, 2017 and 2015 , 6.9 million and 1.2 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 the years ended December 31, 2017 and 2015 , 0.1 million and 0.6 million shares, respectively, 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; the Exchangeable Notes will only become dilutive once the price of IAC common stock exceeds the approximate $152.18 per share exchange price of the Exchangeable Notes. (g) See " Note 13—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, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Changes in Outstanding Stock Options	Stock options outstanding at December 31, 2017 and changes during the year ended December 31, 2017 are as follows: December 31, 2017 Shares Weighted Weighted Aggregate (Shares and intrinsic value in thousands) Options outstanding at January 1, 2017 8,058 $ 52.41 Granted 1,153 76.62 Exercised (2,443 ) 41.30 Forfeited (179 ) 59.34 Expired (3 ) 56.31 Options outstanding at December 31, 2017 6,586 $ 60.57 7.0 $ 406,527 Options exercisable 2,920 $ 55.28 5.6 $ 195,677
Schedule of Information for Stock Options Outstanding and Exercisable	The following table summarizes the information about stock options outstanding and exercisable at December 31, 2017 : Options Outstanding Options Exercisable Range of Exercise Prices Outstanding at Weighted- Weighted- Exercisable at Weighted- Weighted- (Shares in thousands) $10.01 to $20.00 38 0.9 $ 16.67 38 0.9 $ 16.67 $20.01 to $30.00 66 1.5 21.15 66 1.5 21.15 $30.01 to $40.00 415 3.3 32.31 415 3.3 32.31 $40.01 to $50.00 1,862 6.8 43.42 870 5.3 44.86 $50.01 to $60.00 263 4.0 59.47 259 4.0 59.48 $60.01 to $70.00 1,474 7.2 65.00 615 6.9 65.49 $70.01 to $80.00 1,952 8.4 75.30 407 7.3 74.16 $80.01 to $90.00 500 7.3 84.31 250 7.3 84.31 Greater than $90.01 16 9.9 125.06 — — — 6,586 7.0 $ 60.57 2,920 5.6 $ 55.28
Schedule of Weighted Average Assumptions	The following are the weighted average assumptions used in the Black-Scholes option pricing model: Years Ended December 31, 2017 2016 2015 Expected volatility 29 % 29 % 28 % Risk-free interest rate 2.0 % 1.2 % 1.6 % Expected term 5.2 years 4.8 years 5.3 years Dividend yield — % — % 2.0 %
Schedule of Outstanding Unvested RSUs and PSUs	Unvested RSUs and PSUs outstanding at December 31, 2017 and changes during the year ended December 31, 2017 are as follows: RSUs PSUs Number Weighted Number Weighted (Shares in thousands) Unvested at January 1, 2017 526 $ 57.41 — $ — Granted 174 100.54 130 76.00 Vested (340 ) 54.66 — — Forfeited — — — — Unvested at December 31, 2017 360 $ 80.81 130 $ 76.00

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	Years Ended December 31, 2017 2016 2015 (In thousands) Revenue: Match Group $ 1,330,661 $ 1,118,110 $ 909,705 ANGI Homeservices 736,386 498,890 361,201 Video 276,994 228,649 213,317 Applications 577,998 604,140 760,748 Publishing 361,837 407,313 691,686 Other (a) 23,980 283,365 294,821 Inter-segment elimination (617 ) (585 ) (545 ) Total $ 3,307,239 $ 3,139,882 $ 3,230,933 ___________________ (a) The Other segment consists of the results of PriceRunner, ShoeBuy and The Princeton Review for periods prior to the sales of these businesses, which occurred on March 18, 2016, December 30, 2016 and March 31, 2017, respectively. Beginning in the second quarter of 2017, as a result of the sales of these businesses, the Other segment does not include any financial results. Years Ended December 31, 2017 2016 2015 (In thousands) Operating Income (Loss): Match Group $ 360,517 $ 315,549 $ 212,981 ANGI Homeservices (149,176 ) 25,363 (1,568 ) Video (35,659 ) (27,656 ) (38,756 ) Applications 130,176 109,663 175,145 Publishing 15,670 (334,417 ) (26,692 ) Other (5,621 ) (11,678 ) (28,611 ) Corporate (127,441 ) (109,449 ) (112,911 ) Total $ 188,466 $ (32,625 ) $ 179,588 Years Ended December 31, 2017 2016 2015 (In thousands) Adjusted EBITDA: (b) Match Group $ 468,941 $ 403,380 $ 284,554 ANGI Homeservices 37,858 45,851 16,713 Video (30,446 ) (21,247 ) (38,384 ) Applications 136,757 132,276 184,258 Publishing 31,470 (7,571 ) 87,788 Other (1,532 ) 1,802 4,734 Corporate (67,755 ) (53,272 ) (53,873 ) Total $ 575,293 $ 501,219 $ 485,790 December 31, 2017 2016 (In thousands) Segment Assets: (c) Match Group $ 467,338 $ 422,509 ANGI Homeservices 264,450 74,106 Video 129,855 225,519 Applications 345,532 98,460 Publishing 182,949 398,958 Other — 15,372 Corporate 873,392 822,687 Total $ 2,263,516 $ 2,057,611 Years Ended December 31, 2017 2016 2015 (In thousands) Capital expenditures: Match Group $ 28,833 $ 46,098 $ 25,246 ANGI Homeservices 26,837 16,660 10,170 Video 400 2,508 2,466 Applications 227 1,196 4,681 Publishing 850 2,093 6,283 Other 536 5,712 7,085 Corporate 17,840 3,772 6,118 Total $ 75,523 $ 78,039 $ 62,049 _______________________________________________________________________________ (b) 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 business as a whole and our individual business segments, and this measure is one of the primary metrics by 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, and we believe that by excluding these items, Adjusted EBITDA corresponds more closely to the cash operating income generated from our business, from which capital investments are made and debt is serviced. Adjusted EBITDA has certain limitations in that it does not take into account the impact to IAC's statement of operations of certain expenses. (c) 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. The following table presents the revenue of the Company's principal segments disaggregated by type of service: Years Ended December 31, 2017 2016 2015 (In thousands) Match Group Direct revenue $ 1,281,249 $ 1,067,364 $ 866,583 Indirect revenue (principally advertising revenue) 49,412 50,746 43,122 Total Match Group revenue $ 1,330,661 $ 1,118,110 $ 909,705 ANGI Homeservices Marketplace: Consumer connection revenue (d) $ 521,481 $ 382,466 $ 269,309 Membership subscription revenue 56,135 43,573 24,164 Other revenue 3,798 2,827 3,423 Marketplace revenue 581,414 428,866 296,896 Advertising & Other revenue (e) 97,483 32,981 32,971 North America 678,897 461,847 329,867 Consumer connection revenue (d) 40,009 28,124 23,298 Membership subscription revenue 16,596 7,936 6,921 Advertising and other revenue 884 983 1,115 Europe 57,489 37,043 31,334 Total ANGI Homeservices revenue $ 736,386 $ 498,890 $ 361,201 Applications Advertising $ 515,405 $ 552,410 $ 728,501 Subscription (including downloadable app fees) and Other 62,593 51,730 32,247 Total Applications revenue $ 577,998 $ 604,140 $ 760,748 Publishing Advertising $ 358,472 $ 405,031 $ 685,440 Other 3,365 2,282 6,246 Total Publishing revenue $ 361,837 $ 407,313 $ 691,686 _______________________________________________________________________________ (d) Fees paid by service professionals for consumer matches. (e) Includes Angie's List revenue from service professionals under contract for advertising and Angie's List membership subscription fees from consumers, as well as revenue from mHelpDesk, HomeStars and Felix.
Schedule of Revenue by Geographic Areas	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, 2017 2016 2015 (In thousands) Revenue United States $ 2,323,050 $ 2,318,976 $ 2,376,035 All other countries 984,189 820,906 854,898 Total $ 3,307,239 $ 3,139,882 $ 3,230,933
Schedule of Long-lived Assets by Geographic Areas	December 31, 2017 2016 (In thousands) Long-lived assets (excluding goodwill and intangible assets) United States $ 286,541 $ 281,725 All other countries 28,629 24,523 Total $ 315,170 $ 306,248
Schedule of Reconciliation of Adjusted EBITDA to Operating Income (Loss)	The following tables reconcile operating income (loss) for the Company's reportable segments and net earnings (loss) attributable to IAC shareholders to Adjusted EBITDA: Year Ended December 31, 2017 Operating Stock-Based Depreciation Amortization 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 Video (35,659 ) 401 2,167 2,645 — (30,446 ) Applications 130,176 — 3,863 2,170 548 136,757 Publishing 15,670 — 4,725 11,075 — 31,470 Other (5,621 ) 1,729 836 1,524 — (1,532 ) Corporate (127,441 ) 44,168 15,518 — — (67,755 ) Total $ 188,466 $ 264,618 $ 74,265 $ 42,143 $ 5,801 $ 575,293 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 Compensation Expense 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 Video (27,656 ) 640 1,785 4,176 (192 ) — (21,247 ) Applications 109,663 — 5,095 5,483 12,035 — 132,276 Publishing (334,417 ) — 8,531 42,948 — 275,367 (7,571 ) Other (11,678 ) 618 6,219 6,734 (91 ) — 1,802 Corporate (109,449 ) 42,276 13,901 — — — (53,272 ) Total (32,625 ) $ 104,820 $ 71,676 $ 79,426 $ 2,555 $ 275,367 $ 501,219 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 ) Year Ended December 31, 2015 Operating Stock-Based Depreciation Amortization of Intangibles Acquisition-related Contingent Consideration Fair Value Adjustments Goodwill Impairment Adjusted EBITDA (In thousands) Match Group $ 212,981 $ 49,401 $ 19,791 $ 13,437 $ (11,056 ) $ — $ 284,554 ANGI Homeservices (1,568 ) 7,853 6,593 3,835 — — 16,713 Video (38,756 ) 360 1,091 1,558 (2,637 ) — (38,384 ) Applications 175,145 — 4,617 6,264 (1,768 ) — 184,258 Publishing (26,692 ) — 9,577 104,903 — — 87,788 Other (28,611 ) 682 8,652 9,955 — 14,056 4,734 Corporate (112,911 ) 47,154 11,884 — — — (53,873 ) Total 179,588 $ 105,450 $ 62,205 $ 139,952 $ (15,461 ) $ 14,056 $ 485,790 Interest expense (73,636 ) Other income, net 36,938 Earnings before income taxes 142,890 Income tax provision (29,516 ) Net earnings 113,374 Net loss attributable to noncontrolling interests 6,098 Net earnings attributable to IAC shareholders $ 119,472
Schedule of Reconciliation of Segment Assets to Total Assets	The following tables reconcile segment assets to total assets: December 31, 2017 Segment Assets 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 Video 129,855 3,076 95,608 1,800 23,322 253,661 Applications 345,532 7,004 447,242 60,600 847 861,225 Publishing 182,949 5,350 — 15,000 3,252 206,551 Other — — — — — — Corporate (f) 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 (g) 66,321 Total Assets $ 5,867,810 December 31, 2016 Segment Assets Property and Equipment, Net Goodwill Indefinite-Lived Definite-Lived Total Assets (In thousands) Match Group $ 422,509 $ 62,954 $ 1,206,538 $ 214,461 $ 3,221 $ 1,909,683 ANGI Homeservices 74,106 23,645 170,611 4,884 5,908 279,154 Video 225,519 4,750 25,239 1,800 4,167 261,475 Applications 98,460 10,559 447,242 60,600 2,481 619,342 Publishing 398,958 10,696 — 15,000 11,441 436,095 Other 15,372 6,774 74,422 23,900 7,588 128,056 Corporate (f) 822,687 186,870 — — — 1,009,557 Total $ 2,057,611 $ 306,248 $ 1,924,052 $ 320,645 $ 34,806 4,643,362 Add: Deferred tax assets (g) 2,511 Total Assets $ 4,645,873 _____________________________________ (f) Corporate assets consist primarily of cash and cash equivalents, marketable securities and IAC's headquarters building. (g) Total segment assets differ from total assets on a consolidated basis as a result of unallocated deferred tax assets.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2017
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) 2018 $ 38,339 2019 36,996 2020 30,594 2021 23,253 2022 19,688 Thereafter 211,649 Total $ 360,519
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 $ 21,994 $ 10,816 $ — $ — $ 32,810 Letters of credit and surety bonds 576 71 — 1,939 2,586 Total commercial commitments $ 22,570 $ 10,887 $ — $ 1,939 $ 35,396

SUPPLEMENTAL CASH FLOW INFORM46

SUPPLEMENTAL CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Schedule of Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information: Years Ended December 31, 2017 2016 2015 (In thousands) Cash paid (received) during the year for: Interest $ 92,461 $ 107,360 $ 51,666 Income tax payments 35,598 69,103 70,762 Income tax refunds (42,025 ) (23,877 ) (5,619 )

CONSOLIDATED FINANCIAL STATEM47

CONSOLIDATED FINANCIAL STATEMENT DETAILS (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Current Assets	December 31, 2017 2016 (In thousands) Other current assets: Prepaid expenses $ 49,350 $ 37,665 Income taxes receivable 33,239 41,352 Capitalized downloadable search toolbar costs, net 31,588 28,737 Production costs 18,570 39,763 Other 52,627 56,551 Other current assets $ 185,374 $ 204,068
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, 2017 2016 (In thousands) Property and equipment, net of accumulated depreciation and amortization: Buildings and leasehold improvements $ 252,511 $ 247,563 Computer equipment and capitalized software 218,529 275,455 Furniture and other equipment 88,930 94,555 Projects in progress 19,094 13,048 Land 7,917 5,117 586,981 635,738 Accumulated depreciation and amortization (271,811 ) (329,490 ) Property and equipment, net of accumulated depreciation and amortization $ 315,170 $ 306,248
Schedule of Accrued Expenses and Other Current Liabilities	December 31, 2017 2016 (In thousands) Accrued expenses and other current liabilities: Accrued employee compensation and benefits $ 108,431 $ 106,301 Accrued advertising expense 96,445 68,916 Other 162,048 169,693 Accrued expenses and other current liabilities $ 366,924 $ 344,910
Schedule of Revenue	Years Ended December 31, 2017 2016 2015 (In thousands) Revenue: Service revenue $ 3,302,937 $ 2,967,474 $ 3,077,080 Product revenue 4,302 172,408 153,853 Revenue $ 3,307,239 $ 3,139,882 $ 3,230,933
Schedule of Cost of Revenue	Years Ended December 31, 2017 2016 2015 (In thousands) Cost of revenue: Cost of service revenue $ 647,226 $ 617,058 $ 652,137 Cost of product revenue 3,782 138,672 126,024 Cost of revenue $ 651,008 $ 755,730 $ 778,161
Schedule of Other (Expense) Income, Net	Years Ended December 31, 2017 2016 2015 (In thousands) Other (expense) income, net $ (16,213 ) $ 60,650 $ 36,938

TRANSACTION AND INTEGRATION R48

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION (Tables)	12 Months Ended
	Dec. 31, 2017
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 for ANGI Homeservices at December 31, 2017 is presented below. Year Ended December 31, 2017 (In thousands) Transaction and integration related costs $ 44,101 Stock-based compensation expense 122,066 Total $ 166,167 December 31, 2017 (In thousands) Charges incurred $ 44,101 Payments made (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, 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 F49

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Guarantor and Nonguarantor Financial Statements [Abstract]
Schedule of Condensed Balance Sheet	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 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 2,076,004 554,998 — (2,631,002 ) — Other non-current assets 170,073 87,306 79,688 (132,435 ) 204,632 Total assets $ 2,888,712 $ 2,114,868 $ 4,296,370 $ (3,432,140 ) $ 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 388,933 — 279,770 (668,703 ) — Other long-term liabilities 511 18,613 186,610 (132,435 ) 73,299 Redeemable noncontrolling interests — — 42,867 — 42,867 IAC shareholders' equity 2,430,028 1,976,131 654,871 (2,631,002 ) 2,430,028 Noncontrolling interests — — 516,795 — 516,795 Total liabilities and shareholders' equity $ 2,888,712 $ 2,114,868 $ 4,296,370 $ (3,432,140 ) $ 5,867,810 Balance sheet at December 31, 2016: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Cash and cash equivalents $ 553,643 $ — $ 775,544 $ — $ 1,329,187 Marketable securities 89,342 — — — 89,342 Accounts receivable, net of allowance — 77,335 142,803 — 220,138 Other current assets 71,152 48,349 84,567 — 204,068 Intercompany receivables — 565,013 1,209,788 (1,774,801 ) — Property and equipment, net of accumulated depreciation and amortization 4,350 199,343 102,555 — 306,248 Goodwill — 412,010 1,512,042 — 1,924,052 Intangible assets, net of accumulated amortization — 83,179 272,272 — 355,451 Investment in subsidiaries 3,659,570 498,054 — (4,157,624 ) — Other non-current assets 52,228 118,624 162,008 (115,473 ) 217,387 Total assets $ 4,430,285 $ 2,001,907 $ 4,261,579 $ (6,047,898 ) $ 4,645,873 Current portion of long-term debt $ 20,000 $ — $ — $ — $ 20,000 Accounts payable, trade 2,697 29,867 30,299 — 62,863 Other current liabilities 42,160 84,827 503,538 — 630,525 Long-term debt, net 405,991 — 1,176,493 — 1,582,484 Income taxes payable — 3,470 30,274 (216 ) 33,528 Intercompany liabilities 1,774,801 — — (1,774,801 ) — Other long-term liabilities 315,414 21,002 51,817 (115,257 ) 272,976 Redeemable noncontrolling interests — — 32,827 — 32,827 IAC shareholders' equity 1,869,222 1,862,741 2,294,883 (4,157,624 ) 1,869,222 Noncontrolling interests — — 141,448 — 141,448 Total liabilities and shareholders' equity $ 4,430,285 $ 2,001,907 $ 4,261,579 $ (6,047,898 ) $ 4,645,873
Schedule of Condensed Statement of Operations	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 425,675 20,755 — (446,430 ) — Interest expense (20,339 ) — (84,956 ) — (105,295 ) Other (expense) income, net (39,207 ) 28,434 (5,440 ) — (16,213 ) Earnings before income taxes 260,497 140,920 111,971 (446,430 ) 66,958 Income tax benefit (provision) 44,427 (119,957 ) 366,580 — 291,050 Net earnings 304,924 20,963 478,551 (446,430 ) 358,008 Net earnings attributable to noncontrolling interests — — (53,084 ) — (53,084 ) Net earnings attributable to IAC shareholders $ 304,924 $ 20,963 $ 425,467 $ (446,430 ) $ 304,924 Comprehensive income attributable to IAC shareholders $ 367,370 $ 7,629 $ 504,558 $ (512,187 ) $ 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 operations for the year ended December 31, 2015: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations IAC Consolidated (In thousands) Revenue $ — $ 1,355,222 $ 1,876,305 $ (594 ) $ 3,230,933 Operating costs and expenses: Cost of revenue (exclusive of depreciation shown separately below) 720 341,351 436,649 (559 ) 778,161 Selling and marketing expense 3,210 624,979 720,172 (68 ) 1,348,293 General and administrative expense 93,090 94,896 324,036 33 512,055 Product development expense 4,311 73,500 118,812 — 196,623 Depreciation 1,918 23,912 36,375 — 62,205 Amortization of intangibles — 102,622 37,330 — 139,952 Goodwill impairment — 14,056 — — 14,056 Total operating costs and expenses 103,249 1,275,316 1,673,374 (594 ) 3,051,345 Operating (loss) income (103,249 ) 79,906 202,931 — 179,588 Equity in earnings of unconsolidated affiliates 215,080 17,353 — (232,433 ) — Interest expense (49,405 ) (6,130 ) (18,101 ) — (73,636 ) Other (expense) income, net (3,172 ) 27,810 12,300 — 36,938 Earnings before income taxes 59,254 118,939 197,130 (232,433 ) 142,890 Income tax benefit (provision) 60,218 (42,072 ) (47,662 ) — (29,516 ) Net earnings 119,472 76,867 149,468 (232,433 ) 113,374 Net loss attributable to noncontrolling interests — — 6,098 — 6,098 Net earnings attributable to IAC shareholders $ 119,472 $ 76,867 $ 155,566 $ (232,433 ) $ 119,472 Comprehensive income attributable to IAC shareholders $ 55,069 $ 73,970 $ 89,158 $ (163,128 ) $ 55,069
Schedule of Condensed Statement of Cash Flows	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 $ (61,002 ) $ 131,581 $ 346,111 $ 416,690 Cash flows from investing activities: Acquisitions, net of cash acquired — (2,550 ) (146,544 ) (149,094 ) Capital expenditures (337 ) (1,050 ) (74,136 ) (75,523 ) Proceeds from maturities and sales of marketable debt securities 114,350 — — 114,350 Purchases of marketable debt securities (29,891 ) — — (29,891 ) Purchases of investments — — (9,106 ) (9,106 ) Net proceeds from the sale of businesses and investments 1,266 — 184,512 185,778 Other, net — 1,944 1,050 2,994 Net cash provided by (used in) investing activities 85,388 (1,656 ) (44,224 ) 39,508 Cash flows from financing activities: Proceeds from issuance of IAC debt — — 517,500 517,500 Principal payments on 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 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (93,832 ) — — (93,832 ) Proceeds from the exercise of Match Group stock options — — 59,442 59,442 Withholding taxes paid on behalf of Match Group employees on net settled stock-based awards — — (254,210 ) (254,210 ) Proceeds from the exercise of ANGI Homeservices stock options — — 1,653 1,653 Withholding taxes paid on behalf of ANGI employees on net settled stock-based awards — — (10,113 ) (10,113 ) 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 ) Funds returned from escrow for MyHammer tender offer — — 10,604 10,604 Decrease in restricted cash related to bond redemptions 20,141 — — 20,141 Intercompany 424,816 (129,925 ) (294,891 ) — Other, net 251 — (5,251 ) (5,000 ) Net cash provided by (used in) financing activities 7,535 (129,925 ) (43,734 ) (166,124 ) Total cash provided 31,921 — 258,153 290,074 Effect of exchange rate changes on cash and cash equivalents 75 — 11,473 11,548 Net increase in cash and cash equivalents 31,996 — 269,626 301,622 Cash and cash equivalents at beginning of period 553,643 — 775,544 1,329,187 Cash and cash equivalents at end of period $ 585,639 $ — $ 1,045,170 $ 1,630,809 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 ) $ 128,473 $ 278,354 $ — $ 344,141 Cash flows from investing activities: Acquisitions, net of cash acquired — — (18,403 ) — (18,403 ) Capital expenditures (479 ) (5,762 ) (71,798 ) — (78,039 ) Investments in time deposits — — (87,500 ) — (87,500 ) Proceeds from maturities of time deposits — — 87,500 — 87,500 Proceeds from maturities and sales of marketable debt securities 252,369 — — — 252,369 Purchases of marketable debt securities (313,943 ) — — — (313,943 ) Purchases of investments — — (12,565 ) — (12,565 ) Net proceeds from the sale of businesses and investments 73,843 1,779 96,606 — 172,228 Intercompany (155,104 ) — — 155,104 — Other, net 126 910 10,179 — 11,215 Net cash (used in) provided by investing activities (143,188 ) (3,073 ) 4,019 155,104 12,862 Cash flows from financing activities: Principal payments on 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 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (26,716 ) — — — (26,716 ) Proceeds from the exercise of Match Group stock options — — 39,378 — 39,378 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 ) Funds held in escrow for MyHammer tender offer — — (10,548 ) — (10,548 ) Intercompany 122,965 (122,965 ) 155,104 (155,104 ) — Increase in restricted cash related to bond redemptions (141 ) — — — (141 ) Other, net (313 ) (2,084 ) (308 ) — (2,705 ) Net cash (used in) provided by financing activities (315,141 ) (125,400 ) 92,816 (155,104 ) (502,829 ) Total cash (used) provided (521,015 ) — 375,189 — (145,826 ) Effect of exchange rate changes on cash and cash equivalents — — (6,434 ) — (6,434 ) Net (decrease) increase in cash and cash equivalents (521,015 ) — 368,755 — (152,260 ) Cash and cash equivalents at beginning of period 1,074,658 — 406,789 — 1,481,447 Cash and cash equivalents at end of period $ 553,643 $ — $ 775,544 $ — $ 1,329,187 Statement of cash flows for the year ended December 31, 2015: IAC Guarantor Subsidiaries Non-Guarantor Subsidiaries IAC Consolidated (In thousands) Net cash (used in) provided by operating activities $ (121,331 ) $ 242,554 $ 284,448 $ 405,671 Cash flows from investing activities: Acquisitions, net of cash acquired — (6,078 ) (611,324 ) (617,402 ) Capital expenditures (1,332 ) (13,198 ) (47,519 ) (62,049 ) Proceeds from maturities and sales of marketable debt securities 218,462 — — 218,462 Purchases of marketable debt securities (93,134 ) — — (93,134 ) Purchases of investments (6,978 ) — (27,492 ) (34,470 ) Net proceeds from the sale of businesses and investments 1,277 — 8,136 9,413 Other, net 3,613 385 (7,539 ) (3,541 ) Net cash provided by (used in) investing activities 121,908 (18,891 ) (685,738 ) (582,721 ) Cash flows from financing activities: Principal payment on IAC debt — (80,000 ) — (80,000 ) Proceeds from issuance of Match Group debt — — 788,000 788,000 Debt issuance costs (1,876 ) — (17,174 ) (19,050 ) Fees and expenses related to note exchange — — (6,954 ) (6,954 ) Proceeds from Match Group initial public offering, net of fees and expenses — — 428,789 428,789 Purchase of IAC treasury stock (200,000 ) — — (200,000 ) Dividends (113,196 ) — — (113,196 ) Proceeds from the exercise of IAC stock options 27,325 — — 27,325 Withholding taxes paid on behalf of IAC employees on net settled stock-based awards (65,743 ) — — (65,743 ) Purchase of Match Group stock-based awards — — (23,431 ) (23,431 ) Purchase of noncontrolling interests — — (32,207 ) (32,207 ) Acquisition-related contingent consideration payments — (240 ) (5,510 ) (5,750 ) Increase in restricted cash related to bond redemptions (20,000 ) — — (20,000 ) Intercompany 684,716 (143,423 ) (541,293 ) — Other, net 166 — 441 607 Net cash provided by (used in) financing activities 311,392 (223,663 ) 590,661 678,390 Total cash provided 311,969 — 189,371 501,340 Effect of exchange rate changes on cash and cash equivalents — — (10,298 ) (10,298 ) Net increase in cash and cash equivalents 311,969 — 179,073 491,042 Cash and cash equivalents at beginning of period 762,689 — 227,716 990,405 Cash and cash equivalents at end of period $ 1,074,658 $ — $ 406,789 $ 1,481,447

QUARTERLY RESULTS (UNAUDITED) (

QUARTERLY RESULTS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Results	Quarter Ended March 31 Quarter Ended June 30 Quarter Ended September 30 (a) (c) Quarter Ended December 31 (b) (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 (e) $ 0.34 $ 0.84 $ 2.22 $ 0.40 Diluted earnings per share (e) $ 0.29 $ 0.70 $ 1.79 $ 0.37 Quarter Ended March 31 (d) Quarter Ended June 30 (e) Quarter Ended September 30 Quarter Ended December 31 (d) (In thousands, except per share data) Year Ended December 31, 2016 Revenue $ 819,179 $ 745,439 $ 764,102 $ 811,162 Cost of revenue 193,734 170,397 179,131 212,468 Operating income (loss) 21,417 (252,446 ) 85,584 112,820 Net earnings (loss) 7,934 (190,542 ) 52,340 114,117 Net earnings (loss) attributable to IAC shareholders 8,282 (194,775 ) 43,162 102,051 Per share information attributable to IAC shareholders: Basic earnings (loss) per share (e) $ 0.10 $ (2.45 ) $ 0.54 $ 1.29 Diluted earnings (loss) per share (e) $ 0.09 $ (2.45 ) $ 0.49 $ 1.18 _______________________________________________________________________________ (a) The third quarter of 2017 includes after-tax stock-based compensation expense of $60.9 million related primarily 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. (b) The fourth quarter of 2017 includes after-tax stock-based compensation expense of $15.8 million related primarily 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). (c) The third quarter of 2017 includes 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. (d) The first quarter and fourth quarter of 2016 include after-tax gains of $11.9 million and $37.5 million related to the sale of PriceRunner and ShoeBuy, respectively. (e) The second quarter of 2016 includes after-tax impairment charges related to goodwill and indefinite-lived intangible assets of $183.5 million and $7.2 million , respectively. (f) 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)	12 Months Ended
	Dec. 31, 2017segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	6
Match Group, Inc.
Noncontrolling Interest [Line Items]
Ownership interest (as a percent)	81.20%
Voting interest (as a percent)	97.60%
ANGI Homeservices
Noncontrolling Interest [Line Items]
Ownership interest (as a percent)	86.90%
Voting interest (as a percent)	98.50%

SUMMARY OF SIGNIFICANT ACCOUN52

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NARRATIVE (Details) - USD ($) $ in Thousands, shares in Millions	Oct. 01, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets and Goodwill
Maturity period at purchase (less than)										91 days
Revenue		$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933
Accounts receivable, net of allowance		304,027				220,138				304,027	220,138
Property and equipment, net of accumulated depreciation and amortization		315,170				306,248				315,170	306,248
Goodwill		2,559,066				1,924,052				2,559,066	$ 1,924,052	2,245,364
Discount rate											12.00%
Advertising expense										$ 1,100,000	$ 1,000,000	1,200,000
Estimated weighted-average useful life (in years)										18 months
Amounts reclassified to earnings										$ 3,360	(6,937)	2,334
Adjustment of redeemable noncontrolling interests to fair value											(7,560)	0
Acquisition-related contingent consideration payment										11,140	0	0
Contingent consideration liability										15,000
Excess tax benefit, amount										$ 361,800
Accounting Standards Update 2016-09
Intangible Assets and Goodwill
New accounting standard (in shares)										2.4
Foreign Currency Translation Adjustment
Intangible Assets and Goodwill
Amounts reclassified to earnings										$ (673)	(9,850)	2,191
Redeemable Noncontrolling Interest
Intangible Assets and Goodwill
Adjustment of redeemable noncontrolling interests to fair value										$ 6,300	$ 7,900	23,200
Minimum
Intangible Assets and Goodwill
Discount rate										12.50%	10.00%
Maximum
Intangible Assets and Goodwill
Discount rate										17.50%	17.50%
Match Group
Intangible Assets and Goodwill
Deferred revenue		198,300				161,100				$ 198,300	$ 161,100
Market capitalization	$ 6,300,000
Percentage of market capitalization (more than)	1100.00%
Goodwill		1,247,899				1,206,538				$ 1,247,899	1,206,538	1,218,607
Match Group | Minimum
Intangible Assets and Goodwill
Revenue recognition period										1 month
Match Group | Maximum
Intangible Assets and Goodwill
Revenue recognition period										6 months
ANGI Homeservices
Intangible Assets and Goodwill
Deferred revenue		64,100				18,800				$ 64,100	18,800
Period of advertising contract term										1 year
Market capitalization	$ 5,900,000
Percentage of market capitalization (more than)	450.00%
Goodwill		768,317				170,611				$ 768,317	170,611	150,251
Angie's List
Intangible Assets and Goodwill
Deferred revenue		37,700								37,700
Vimeo
Intangible Assets and Goodwill
Deferred revenue		49,400				36,700				49,400	36,700
Electus
Intangible Assets and Goodwill
Deferred revenue		12,800				23,100				12,800	23,100
Applications
Intangible Assets and Goodwill
Deferred revenue		23,600				26,100				23,600	26,100
Goodwill		447,242				447,242				447,242	447,242	447,242
Publishing
Intangible Assets and Goodwill
Goodwill						0					0	277,192
Asset impairment charges								275,400
Daily Burn and Electus
Intangible Assets and Goodwill
Excess of goodwill over carrying value, more than (less than) (as percent)	120.00%
Goodwill	$ 450,000
Other
Intangible Assets and Goodwill
Goodwill		0				74,422				0	74,422	136,482
Operating Segments | Match Group
Intangible Assets and Goodwill
Revenue										1,330,661	1,118,110	909,705
Operating Segments | ANGI Homeservices
Intangible Assets and Goodwill
Revenue										736,386	498,890	361,201
Property and equipment, net of accumulated depreciation and amortization		53,292				23,645				53,292	23,645
Goodwill		768,317				170,611				768,317	170,611
Operating Segments | Applications
Intangible Assets and Goodwill
Revenue										577,998	604,140	760,748
Property and equipment, net of accumulated depreciation and amortization		7,004				10,559				7,004	10,559
Goodwill		447,242				447,242				447,242	447,242
Operating Segments | Publishing
Intangible Assets and Goodwill
Revenue										361,837	407,313	691,686
Property and equipment, net of accumulated depreciation and amortization		5,350				10,696				5,350	10,696
Goodwill		0				0				0	0
Operating Segments | Other
Intangible Assets and Goodwill
Revenue										23,980	283,365	294,821
Property and equipment, net of accumulated depreciation and amortization		0				6,774				0	6,774
Goodwill		0				74,422				$ 0	$ 74,422
Indefinite-lived Intangible Assets | Minimum
Intangible Assets and Goodwill
Discount rate										11.00%	11.00%
Royalty rate										2.00%	2.00%
Indefinite-lived Intangible Assets | Maximum
Intangible Assets and Goodwill
Discount rate										16.00%	16.00%
Royalty rate										7.00%	7.00%
Indefinite-lived Intangible Assets | Publishing
Intangible Assets and Goodwill
Asset impairment charges								$ 11,600				88,000
Indefinite-lived Intangible Assets | Other
Intangible Assets and Goodwill
Asset impairment charges												14,100
Google Inc.
Intangible Assets and Goodwill
Accounts receivable, net of allowance		72,400				65,800				$ 72,400	$ 65,800
Google Inc. | Publishing and Applications
Intangible Assets and Goodwill
Revenue										$ 740,700	$ 824,400	$ 1,300,000
Customer Concentration Risk | Google Inc. | Revenue
Intangible Assets and Goodwill
Concentration risk (as a percent)										22.00%	26.00%	40.00%
Customer Concentration Risk | Google Inc. | Revenue | Operating Segments | Applications
Intangible Assets and Goodwill
Concentration risk (as a percent)										83.00%	87.00%	94.00%
Customer Concentration Risk | Google Inc. | Revenue | Operating Segments | Publishing
Intangible Assets and Goodwill
Concentration risk (as a percent)										71.00%	73.00%	83.00%
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-15
Intangible Assets and Goodwill
Acquisition-related contingent consideration payment										$ 11,100
Subscription term, one month | ANGI Homeservices
Intangible Assets and Goodwill
Period of membership subscription										1 month
Subscription term, one month | Vimeo
Intangible Assets and Goodwill
Period of membership subscription										1 month
Subscription term, one month | Applications
Intangible Assets and Goodwill
Period of membership subscription										1 year
Subscription term, three months | ANGI Homeservices
Intangible Assets and Goodwill
Period of membership subscription										3 months
Subscription term, three months | Vimeo
Intangible Assets and Goodwill
Period of membership subscription										1 year
Subscription term, three months | Applications
Intangible Assets and Goodwill
Period of membership subscription										2 years
Subscription term, one year | ANGI Homeservices
Intangible Assets and Goodwill
Period of membership subscription										1 year
Trade Names | Indefinite-lived Intangible Assets | Minimum
Intangible Assets and Goodwill
Royalty rate										2.00%
Trade Names | Indefinite-lived Intangible Assets | Maximum
Intangible Assets and Goodwill
Royalty rate										6.00%
Software and software development costs
Intangible Assets and Goodwill
Property and equipment, net of accumulated depreciation and amortization		$ 46,400				$ 46,900				$ 46,400	$ 46,900
Other (Expense) Income, Net | Foreign Currency Translation Adjustment
Intangible Assets and Goodwill
Amounts reclassified to earnings										$ 700	$ 9,900	$ 2,200

SUMMARY OF SIGNIFICANT ACCOUN53

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SCHEDULE OF ESTIMATED USEFUL LIVES OF PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property and equipment, net of accumulated depreciation and amortization:
Net book value	$ 315,170	$ 306,248
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
Software and software development costs
Property and equipment, net of accumulated depreciation and amortization:
Net book value	$ 46,400	$ 46,900

INCOME TAXES - NARRATIVE (Detai

INCOME TAXES - NARRATIVE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards
Income tax benefit related to net operating loss carryforwards	$ 257,700
Income tax benefit attributed to a reduction of goodwill	79,200
Tax Credit Carryforwards
Tax credit carryforwards	87,600
Tax credit carryforwards that can be carried forward indefinitely	15,200
Tax credit carryforwards expiring primarily by 2018 and 2037	72,400
Deferred tax assets	514,068	$ 264,912
Valuation Allowance
Decrease in valuation allowance	44,400
Valuation allowance at end of period	132,600
Federal
Operating Loss Carryforwards
Net operating loss carryforwards	850,200
Net operating loss carryforwards not subject to expiration	586,800
Capital loss carryforwards	11,300
Tax Credit Carryforwards
Deferred tax assets	130,000
State
Operating Loss Carryforwards
Net operating loss carryforwards	859,400
Net operating loss carryforwards not subject to expiration	496,000
Capital loss carryforwards	30,900
Tax Credit Carryforwards
Tax credit carryforwards	7,200
Foreign
Operating Loss Carryforwards
Net operating loss carryforwards	378,200
Net operating loss carryforwards not subject to expiration	355,400
Net operating loss carryforwards subject to expiration within 20 years	22,800
Tax Credit Carryforwards
Tax credit carryforwards	49,300
Provisional transition tax calculation	41,800
Research and development	$ 31,100

INCOME TAXES - SCHEDULE OF INCO

INCOME TAXES - SCHEDULE OF INCOME BEFORE INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S.	$ (52,606)	$ (248,433)	$ 79,656
Foreign	119,564	167,348	63,234
Earnings (loss) before income taxes	$ 66,958	$ (81,085)	$ 142,890

INCOME TAXES - SCHEDULE OF COMP

INCOME TAXES - SCHEDULE OF COMPONENTS OF INCOME TAX EXPENSE (BENEFIT) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current income tax (benefit) provision:
Federal		$ (31,844)	$ 23,343	$ 67,505
State		1,964	3,662	7,785
Foreign		24,108	27,242	14,012
Current income tax (benefit) provision		(5,772)	54,247	89,302
Deferred income tax (benefit) provision:
Federal		(255,477)	(100,798)	(50,254)
State		(28,364)	(9,518)	(3,727)
Foreign		(1,437)	(8,865)	(5,805)
Deferred income tax (benefit) provision		(285,278)	(119,181)	(59,786)
Income tax (benefit) provision	$ 257,000	(291,050)	(64,934)	29,516
Excess tax benefit, amount		$ 361,800
Excess tax benefits from stock-based awards			$ 51,800	$ 56,400

INCOME TAXES - SCHEDULE OF IN57

INCOME TAXES - SCHEDULE OF INCOME TAXES (PAYABLE) RECEIVABLE AND DEFERRED TAX (LIABILITIES) ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other current assets	$ 33,239	$ 41,352
Income taxes payable	(25,624)	(33,528)
Net income taxes receivable	(2,234)
Net income taxes (payable)		3,651
Other non-current assets	66,321	2,511
Deferred income taxes	(35,070)	(228,798)
Net deferred tax assets	31,251
Net deferred tax assets (liabilities)		(226,287)
Other current assets
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other current assets	33,239	41,352
Other non-current assets
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Other non-current assets	1,949	1,615
Other non-current assets	66,321	2,511
Accrued expenses and other current liabilities
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Accrued expenses and other current liabilities	(11,798)	(5,788)
Income taxes payable
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Income taxes payable	(25,624)	(33,528)
Deferred income taxes
Income Taxes (Payable) Receivable and Deferred Tax (Liabilities) Assets
Deferred income taxes	$ (35,070)	$ (228,798)

INCOME TAXES - SCHEDULE OF DEFE

INCOME TAXES - SCHEDULE OF DEFERRED TAX ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Accrued expenses	$ 22,234	$ 40,273
NOL carryforwards	292,812	63,948
Tax credit carryforwards	78,715	11,570
Stock-based compensation	77,976	87,914
Equity method investments	12,066	17,455
Intangible and other assets	0	13,708
Other	30,265	30,044
Total deferred tax assets	514,068	264,912
Less valuation allowance	(132,598)	(88,170)
Net deferred tax assets	381,470	176,742
Deferred tax liabilities:
Investment in subsidiaries	(247,167)	(385,474)
Intangible and other assets	(87,811)
Other	(15,241)	(17,555)
Total deferred tax liabilities	(350,219)	(403,029)
Net deferred tax assets	$ 31,251
Net deferred tax assets (liabilities)		$ (226,287)

INCOME TAXES - SCHEDULE OF EFFE

INCOME TAXES - SCHEDULE OF EFFECTIVE INCOME TAX RATE RECONCILIATION (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax (benefit) provision at the federal statutory rate of 35%		$ 23,435	$ (28,446)	$ 50,006
Transition tax		62,667	0	0
Stock-based compensation		(358,901)	3,998	1,787
Foreign income taxed at a different statutory tax rate		(14,725)	(27,115)	(10,382)
State income taxes, net of effect of federal tax benefit		86	(3,880)	2,208
Realization of certain deferred tax assets		(3,133)	0	(22,440)
Non-taxable sale and non-deductible goodwill associated with ShoeBuy		0	(13,142)	4,920
Goodwill impairment of Publishing		0	10,649	0
Research credit		(5,304)	(2,231)	(2,354)
Non-deductible impairments for certain cost method investments		2,669	3,489	2,341
Deferred tax adjustment for enacted changes in tax laws and rates		705	(4,594)	0
Other, net		1,451	(3,662)	3,430
Income tax (benefit) provision	$ 257,000	$ (291,050)	$ (64,934)	$ 29,516
Federal statutory income tax rate (percentage)		35.00%	35.00%	35.00%

INCOME TAXES - SCHEDULE OF IN60

INCOME TAXES - SCHEDULE OF INCOME TAX CONTINGENCIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Balance at beginning of the period	$ 38,372	$ 40,808	$ 30,386
Additions based on tax positions related to the current year	2,050	2,033	4,227
Additions for tax positions of prior years	1,994	2,676	14,467
Reductions for tax positions of prior years	(3,761)	(743)	(1,556)
Settlements	0	(5,107)
Expiration of applicable statutes of limitations	(1,923)	(1,295)	(6,716)
Balance at end of the period	36,732	38,372	40,808
Income Tax Contingency
Interest on income taxes accrued	3,000	2,600
Income tax penalties accrued	1,700	1,700
Unrecognized tax benefits including tax interest accrued	39,700	41,000
Tax positions for which the ultimate deductibility is highly certain but timing is uncertain	37,200	37,700
Change in unrecognized tax benefits unrelated to Federal income taxes statute of limitations expiring within twelve months of current reporting period	13,200
Tax Benefits that would impact effective tax rate	12,900
Tax Cuts and Jobs Act, provisional income tax expense	63,800
Tax Cuts and Jobs Act, transition tax	62,700
Tax Cuts and Jobs Act, remeasurement	1,100
Tax Cuts and Jobs Act, foreign cash	452,200
Tax Cuts and Jobs Act, foreign cash able to be repatriated	420,200
Tax Cuts and Jobs Act, tax on cash earnings of foreign subsidiaries	7,900
Tax Cuts and Jobs Act, cash earnings of foreign subsidiaries	101,200
Continuing Operations
Income Tax Contingency
Unrecognized tax benefit (expense) net of related deferred taxes	(100)	400	100
Deferred taxes for interest on unrecognized tax benefits (continuing operations)	$ 100	$ 200	$ 100

BUSINESS COMBINATION - NARRATIV

BUSINESS COMBINATION - NARRATIVE (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Sep. 29, 2017	Dec. 31, 2017	Dec. 31, 2016
Angie's List
Business Acquisition [Line Items]
Percentage of voting interests acquired	100.00%
Total purchase price	$ 781,384
Net assets acquired	$ 781,384
Basis of purchase price (in shares)	61.3
Share price (in dollars per share)	$ 12.46
Cash acquisition price	$ 1,900
Cash per share paid to acquiree shareholders' who elected payout (in dollars per share)	$ 8.50
Revenue		$ 58,900
Net earnings		(21,800)
One-Time Acquisition-related Costs
Business Acquisition [Line Items]
Severance and retention Costs		19,800
Severance costs		28,700
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		78,000	$ (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, 2017	Sep. 29, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 2,559,066		$ 1,924,052	$ 2,245,364
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 - PRELIM64

BUSINESS COMBINATION - PRELIMINARY ESTIMATED FAIR VALUE OF INTANGIBLE ASSETS ACQUIRED (Details) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2017
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 - SCHEDULE

BUSINESS COMBINATION - SCHEDULE OF PRO FORMA FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	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 IAC shareholders	$ 364,496	$ (143,133)
Basic earnings (loss) per share attributable to IAC shareholders (in dollars per share)	$ 4.55	$ (1.79)
Diluted earnings (loss) per share attributable to IAC shareholders (in dollars per share)	$ 4.27	$ (1.79)

GOODWILL AND INTANGIBLE ASSET66

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF GOODWILL AND INTANGIBLE ASSETS, NET (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 2,559,066	$ 1,924,052	$ 2,245,364
Intangible assets with indefinite lives	459,143	320,645
Intangible assets with definite lives, net of accumulated amortization	204,594	34,806
Total goodwill and intangible assets, net	$ 3,222,803	$ 2,279,503

GOODWILL AND INTANGIBLE ASSET67

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF GOODWILL BY REPORTING UNIT (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Balance at beginning of period		$ 1,924,052	$ 2,245,364
Additions		661,396	32,237
(Deductions)		(74,430)	(67,811)
Impairment		0	(275,367)	$ (14,056)
Foreign Exchange Translation		48,048	(10,371)
Balance at end of period		2,559,066	1,924,052	2,245,364
Match Group
Goodwill
Balance at beginning of period		1,206,538	1,218,607
Additions		255	603
(Deductions)		0	(2,983)
Impairment			0
Foreign Exchange Translation		41,106	(9,689)
Balance at end of period		1,247,899	1,206,538	1,218,607
ANGI Homeservices
Goodwill
Balance at beginning of period		170,611	150,251
Additions		590,772	21,985
(Deductions)		0	0
Impairment			0
Foreign Exchange Translation		6,934	(1,625)
Balance at end of period		768,317	170,611	150,251
Video
Goodwill
Balance at beginning of period		25,239	15,590
Additions		70,369	9,649
(Deductions)		0	0
Impairment			0
Foreign Exchange Translation		0	0
Balance at end of period		95,608	25,239	15,590
Accumulated goodwill impairment loss		11,600
Applications
Goodwill
Balance at beginning of period		447,242	447,242
Additions		0	0
(Deductions)		0	0
Impairment			0
Foreign Exchange Translation		0	0
Balance at end of period		447,242	447,242	447,242
Accumulated goodwill impairment loss		529,100
Publishing
Goodwill
Balance at beginning of period		0	277,192
Additions			0
(Deductions)			(1,968)
Impairment	$ 275,400		(275,367)
Foreign Exchange Translation			143
Balance at end of period			0	277,192
Accumulated goodwill impairment loss		598,000
Other
Goodwill
Balance at beginning of period		74,422	136,482
Additions		0	0
(Deductions)		(74,430)	(62,860)
Impairment			0
Foreign Exchange Translation		8	800
Balance at end of period		0	74,422	136,482
Operating Segments | Match Group
Goodwill
Impairment			0	0
Operating Segments | ANGI Homeservices
Goodwill
Balance at beginning of period		170,611
Impairment			0	0
Balance at end of period		768,317	170,611
Operating Segments | Video
Goodwill
Balance at beginning of period		25,239
Impairment			0	0
Balance at end of period		95,608	25,239
Operating Segments | Applications
Goodwill
Balance at beginning of period		447,242
Impairment			0	0
Balance at end of period		447,242	447,242
Operating Segments | Publishing
Goodwill
Balance at beginning of period		0
Impairment			(275,367)	0
Balance at end of period		0	0
Operating Segments | Other
Goodwill
Balance at beginning of period		74,422
Impairment			0	$ (14,056)
Balance at end of period		$ 0	$ 74,422

GOODWILL AND INTANGIBLE ASSET68

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF INTANGIBLE ASSETS WITH DEFINITE LIVES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Intangible assets with definite lives
Gross Carrying Amount	$ 279,551	$ 136,974
Accumulated Amortization	(74,957)	(102,168)
Total	$ 204,594	$ 34,806
Weighted-average useful life (years)	3 years 8 months 12 days	2 years 9 months 18 days
Contractor and service professional relationships and other
Intangible assets with definite lives
Gross Carrying Amount	$ 102,997	$ 7,230
Accumulated Amortization	(13,252)	(2,612)
Total	$ 89,745	$ 4,618
Weighted-average useful life (years)	3 years	4 years 6 months
Technology
Intangible assets with definite lives
Gross Carrying Amount	$ 115,200	$ 38,602
Accumulated Amortization	(37,357)	(27,667)
Total	$ 77,843	$ 10,935
Weighted-average useful life (years)	4 years 9 months 18 days	3 years 4 months 24 days
Customer lists and user base
Intangible assets with definite lives
Gross Carrying Amount	$ 23,468	$ 12,485
Accumulated Amortization	(5,401)	(9,997)
Total	$ 18,067	$ 2,488
Weighted-average useful life (years)	2 years 2 months 12 days	3 years 8 months 12 days
Content
Intangible assets with definite lives
Gross Carrying Amount	$ 5,000	$ 14,802
Accumulated Amortization	(3,973)	(8,965)
Total	$ 1,027	$ 5,837
Weighted-average useful life (years)	5 years	4 years 3 months 18 days
Trade names
Intangible assets with definite lives
Gross Carrying Amount	$ 16,986	$ 63,855
Accumulated Amortization	(13,634)	(52,927)
Total	$ 3,352	$ 10,928
Weighted-average useful life (years)	2 years 7 months 6 days	1 year 9 months 18 days
Memberships
Intangible assets with definite lives
Gross Carrying Amount	$ 15,900
Accumulated Amortization	(1,340)
Total	$ 14,560
Weighted-average useful life (years)	3 years

GOODWILL AND INTANGIBLE ASSET69

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF EXPECTED AMORTIZATION OF INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 72,395
2,019	56,624
2,020	44,438
2,021	12,529
2,022	10,650
Thereafter	7,958
Total	$ 204,594	$ 34,806

MARKETABLE SECURITIES - SCHEDUL

MARKETABLE SECURITIES - SCHEDULE OF CURRENT AVAILABLE-FOR-SALE MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Marketable Securities
Amortized Cost	$ 4,995	$ 89,350
Gross Unrealized Gains	0	2
Gross Unrealized Losses	0	(10)
Fair Value	4,995	89,342
Commercial paper
Schedule of Available-for-sale Marketable Securities
Amortized Cost	4,995	49,797
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 4,995	49,797
Treasury discount notes
Schedule of Available-for-sale Marketable Securities
Amortized Cost		34,978
Gross Unrealized Gains		0
Gross Unrealized Losses		(4)
Fair Value		34,974
Corporate debt securities
Schedule of Available-for-sale Marketable Securities
Amortized Cost		4,575
Gross Unrealized Gains		2
Gross Unrealized Losses		(6)
Fair Value		$ 4,571

MARKETABLE SECURITIES - SCHED71

MARKETABLE SECURITIES - SCHEDULE OF PROCEEDS FROM MATURITIES AND SALES OF CURRENT AVAILABLE-FOR-SALE MARKETABLE SECURITIES (Details 2) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Marketable Securities [Abstract]
Gross unrealized loss			$ 37,000,000
Proceeds from maturities and sales of available-for-sale marketable securities		$ 114,350,000	279,485,000	$ 218,976,000
Gross realized gains		0	3,556,000	443,000
Gross realized losses	$ 300,000	$ 0	$ 0	$ 0
Match Group | PlentyOfFish
Business Acquisition [Line Items]
Cash acquisition price	$ 575,000,000

LONG-TERM INVESTMENTS - NARRATI

LONG-TERM INVESTMENTS - NARRATIVE (Details) - USD ($) $ in Millions	Oct. 23, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cost method investments
Long-term investments
After tax other-than-temporary impairment charge		$ 9.5	$ 10	$ 4.5
Equity method investments
Long-term investments
After tax other-than-temporary impairment charge		$ 2.7	$ 0.6
Match Group
Long-term investments
Proceeds from sale of cost method investment	$ 60.2
Gain on sale of investments	$ 9.1

LONG-TERM INVESTMENTS - SCHEDUL

LONG-TERM INVESTMENTS - SCHEDULE OF LONG-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of long-term investments
Total long-term investments	$ 64,977	$ 122,810
Cost method investments
Components of long-term investments
Total long-term investments	63,418	116,133
Equity method investments
Components of long-term investments
Total long-term investments	$ 1,559	$ 6,677

FAIR VALUE MEASUREMENTS AND F74

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - NARRATIVE (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2017USD ($)arrangement
Contingent Consideration Arrangments
Discount rate	12.00%
Current portion of contingent consideration	$ 33.4	$ 0.6
Noncurrent portion of contingent consideration	$ 0.4	$ 2
Contingent Consideration Arrangements
Contingent Consideration Arrangments
Number of contingent consideration arrangements related to business acquisitions | arrangement		3
Maximum amount of contingent consideration		$ 33
Fair value of contingent consideration		$ 3

FAIR VALUE MEASUREMENTS AND F75

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - SCHEDULE OF ASSETS AND LIABILITIES MEASURED AT FAIR VALUE ON A RECURRING BASIS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Marketable securities	$ 4,995	$ 89,342
Fair Value on a Recurring Basis
Assets:
Total	1,167,397	984,635
Liabilities:
Contingent consideration arrangements	(2,647)	(33,871)
Fair Value on a Recurring Basis | Money market funds
Assets:
Cash equivalents	780,425	667,662
Fair Value on a Recurring Basis | Time deposits
Assets:
Cash equivalents	60,000	79,000
Fair Value on a Recurring Basis | Treasury discount notes
Assets:
Cash equivalents	100,457	24,991
Long-term investments		34,974
Fair Value on a Recurring Basis | Commercial paper
Assets:
Cash equivalents	215,325	123,640
Marketable securities	4,995	49,797
Fair Value on a Recurring Basis | Certificates of deposit
Assets:
Cash equivalents	6,195
Fair Value on a Recurring Basis | Corporate debt securities
Assets:
Long-term investments		4,571
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total	880,882	727,627
Liabilities:
Contingent consideration arrangements	0	0
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents	780,425	667,662
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Time deposits
Assets:
Cash equivalents	0	0
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Treasury discount notes
Assets:
Cash equivalents	100,457	24,991
Long-term investments		34,974
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Assets:
Cash equivalents	0	0
Marketable securities	0	0
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Certificates of deposit
Assets:
Cash equivalents	0
Fair Value on a Recurring Basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities
Assets:
Long-term investments		0
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2)
Assets:
Total	286,515	257,008
Liabilities:
Contingent consideration arrangements	0	0
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Money market funds
Assets:
Cash equivalents	0	0
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Time deposits
Assets:
Cash equivalents	60,000	79,000
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Treasury discount notes
Assets:
Cash equivalents	0	0
Long-term investments		0
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents	215,325	123,640
Marketable securities	4,995	49,797
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Certificates of deposit
Assets:
Cash equivalents	6,195
Fair Value on a Recurring Basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Long-term investments		4,571
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3)
Assets:
Total	0	0
Liabilities:
Contingent consideration arrangements	(2,647)	(33,871)
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Money market funds
Assets:
Cash equivalents	0	0
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Time deposits
Assets:
Cash equivalents	0	0
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Treasury discount notes
Assets:
Cash equivalents	0	0
Long-term investments		0
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Cash equivalents	0
Marketable securities	0
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Certificates of deposit
Assets:
Cash equivalents	$ 0
Fair Value on a Recurring Basis | Significant Unobservable Inputs (Level 3) | Corporate debt securities
Assets:
Long-term investments		$ 0

FAIR VALUE MEASUREMENTS AND F76

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - SCHEDULE OF CHANGES IN LEVEL 3 ASSETS AND LIABILITIES MEASURED AT FAIR VALUE ON A RECURRING BASIS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Auction Rate Security
Other		$ 0
Contingent Consideration Arrangements
Other	$ 0	2,133
Contingent Consideration Arrangements
Contingent Consideration Arrangements
Balance at beginning of period	(33,871)	(33,873)
Fair value adjustments	(5,801)	(2,555)
Included in other comprehensive (loss) income	(1,404)	(1,571)
Fair value at date of acquisition	0	(185)
Settlements	38,429	2,180
Proceeds from sale	0	0
Balance at end of period	(2,647)	(33,871)
Auction Rate Security
Auction Rate Security
Balance at beginning of period	$ 0	4,050
Fair value adjustments		0
Included in other comprehensive (loss) income		5,950
Fair value at date of acquisition		0
Settlements		0
Proceeds from sale		(10,000)
Balance at end of period		$ 0

FAIR VALUE MEASUREMENTS AND F77

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - CARRYING VALUE AND FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current portion of long-term debt | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, fair value	$ (13,750)	$ (20,000)
Current portion of long-term debt | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, fair value	(13,802)	(20,311)
Long-term debt, net | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, fair value	(1,979,469)	(1,582,484)
Long-term debt, net | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, fair value	$ (2,168,108)	$ (1,657,861)

LONG-TERM DEBT - NARRATIVE (Det

LONG-TERM DEBT - NARRATIVE (Details)	Nov. 01, 2017USD ($)	Oct. 02, 2017USD ($)$ / sharesshares	Aug. 14, 2017USD ($)	Nov. 16, 2015USD ($)	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)	Dec. 04, 2017	Jun. 01, 2016USD ($)
Debt Instrument
Debt instrument, outstanding balance					$ 2,102,359,000
Proceeds from issuance of IAC debt					$ 517,500,000	$ 0	$ 0
Class of warrant outstanding (in shares) | shares						0
Exercise price of warrants (in dollars per share) | $ / shares					$ 0
Proceeds from issuance of warrants					$ 23,650,000	$ 0	$ 0
Unamortized discount					$ 75,826,000
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%
Revolving Credit Facility | IAC Credit Facility
Debt Instrument
Maximum borrowing capacity					$ 300,000,000
Credit facility, borrowings outstanding					$ 0	$ 0
Commitment fee percentage					0.25%
Revolving Credit Facility | IAC Credit Facility | Maximum
Debt Instrument
Maximum leverage ratio (not more than)					3.25
IAC
Debt Instrument
Debt instrument, outstanding balance					$ 552,359,000	428,323,000
Proceeds from issuance of IAC debt					0
Proceeds from issuance of warrants					23,650,000
Unamortized discount					67,158,000	0
IAC | Senior Notes
Debt Instrument
Debt instrument, outstanding balance		$ 517,500,000			450,300,000
Debt instrument, face amount					$ 74,400,000
Exchangeable shares (in shares) | shares		6.5713
Exchange price (in dollars per share) | $ / shares		$ 152.18			$ 152.18
Period of reported sale price of common stock		20 days
Period of consecutive reported sale price of common stock		30 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
Shares outstanding (in shares) | shares					3,400,000
Class of warrant outstanding (in shares) | shares					3,400,000
Exercise price of warrants (in dollars per share) | $ / shares					$ 229.70
Proceeds from issuance of warrants					$ 23,600,000
Cash and non-cash interest expense		$ 4,300,000
Unamortized discount					$ 67,200,000
IAC | 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)		4.875%			4.875%
Debt instrument, outstanding balance					$ 0	390,214,000
Repayment of debt		$ 361,900,000
Accrued interest		$ 8,800,000
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1, which commences on April 1, 2018
Debt Instrument
Stated interest rate (as a percent)		0.875%			0.875%
Debt instrument, outstanding balance					$ 517,500,000	0
IAC | Senior Notes | 0.875% Exchangeable Senior Notes due October 1, 2022 (the Exchangeable Notes); interest payable each April 1 and October 1, which commences on April 1, 2018 | Minimum
Debt Instrument
Stated interest rate (as a percent)					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, which commences on April 1, 2018 | Maximum
Debt Instrument
Stated interest rate (as a percent)					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%
Debt instrument, outstanding balance					$ 34,859,000	38,109,000
Match Group, Inc.
Debt Instrument
Debt instrument, outstanding balance					1,275,000,000	1,195,172,000
Unamortized discount					$ 8,668,000	5,245,000
Match Group, Inc. | 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%			6.75%
Debt instrument, outstanding balance					$ 0	445,172,000
Match Group, Inc. | Senior Notes | 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
Debt Instrument
Stated interest rate (as a percent)					5.00%			5.00%
Debt instrument, outstanding balance					$ 450,000,000	$ 0
Match Group, Inc. | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1
Debt Instrument
Stated interest rate (as a percent)					6.375%	6.375%			6.375%
Debt instrument, outstanding balance					$ 400,000,000	$ 400,000,000
Debt instrument, face amount									$ 400,000,000
Repayment of debt				$ 400,000,000		450,000,000
Match Group, Inc. | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1 | Maximum
Debt Instrument
Maximum leverage ratio (not more than)					5
Match Group, Inc. | 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%
Match Group, Inc. | Term Loan | Match Group Term Loan due November 16, 2022
Debt Instrument
Debt instrument, outstanding balance			$ 425,000,000
Debt instrument, face amount				$ 800,000,000
Repayment of debt						440,000,000
Proceeds from issuance of IAC debt			$ 75,000,000
Debt instrument, interest rate					3.85%
Match Group, Inc. | 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, Inc. | Term Loan | Match Group Term Loan due November 16, 2022 | LIBOR | Minimum
Debt Instrument
Basis spread on variable rate (as a percent)			0.00%
Match Group, Inc. | Revolving Credit Facility | Match Group Credit Agreement
Debt Instrument
Maximum borrowing capacity					$ 500,000,000
Credit facility, borrowings outstanding					$ 0	$ 0
Commitment fee percentage					0.30%
Match Group, Inc. | Revolving Credit Facility | Match Group Credit Agreement | Minimum
Debt Instrument
Minimum interest coverage ratio (not less than)					2.5
Match Group, Inc. | Revolving Credit Facility | Match Group Credit Agreement | Maximum
Debt Instrument
Maximum leverage ratio (not more than)					5
ANGI Homeservices | Term Loan
Debt Instrument
Debt instrument, face amount	$ 275,000,000
ANGI Homeservices | Term Loan | LIBOR
Debt Instrument
Basis spread on variable rate (as a percent)	2.00%				3.38%
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%

LONG-TERM DEBT - SCHEDULE OF LO

LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($)	Dec. 31, 2017	Dec. 04, 2017	Oct. 02, 2017	Dec. 31, 2016	Jun. 01, 2016	Nov. 16, 2015
Debt Instrument
Total long-term debt	$ 2,102,359,000
Less: unamortized original issue discount and original issue premium, net	75,826,000
Less: unamortized debt issuance costs	33,314,000
Less: Current portion of long-term debt	13,750,000			$ 20,000,000
Long-term debt, net	$ 1,979,469,000			$ 1,582,484,000
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%
IAC
Debt Instrument
Total long-term debt	$ 552,359,000			$ 428,323,000
Less: unamortized original issue discount and original issue premium, net	67,158,000			0
Less: unamortized debt issuance costs	16,740,000			2,332,000
Less: Current portion of long-term debt	0			20,000,000
Long-term debt, net	468,461,000			405,991,000
IAC | Senior Notes
Debt Instrument
Total long-term debt	450,300,000		$ 517,500,000
Less: unamortized original issue discount and original issue premium, net	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, which commences on April 1, 2018
Debt Instrument
Total long-term debt	$ 517,500,000			0
Stated interest rate (as a percent)	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	$ 34,859,000			38,109,000
Stated interest rate (as a percent)	4.75%
IAC | 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
Total long-term debt	$ 0			390,214,000
Stated interest rate (as a percent)	4.875%		4.875%
Match Group, Inc.
Debt Instrument
Total long-term debt	$ 1,275,000,000			1,195,172,000
Less: unamortized original issue discount and original issue premium, net	8,668,000			5,245,000
Less: unamortized debt issuance costs	13,636,000			13,434,000
Long-term debt, net	1,252,696,000			1,176,493,000
Match Group, Inc. | 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
Total long-term debt	$ 0			445,172,000
Stated interest rate (as a percent)	6.75%	6.75%				6.75%
Match Group, Inc. | Senior Notes | 6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% 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, Inc. | Senior Notes | 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
Debt Instrument
Total long-term debt	$ 450,000,000			$ 0
Stated interest rate (as a percent)	5.00%	5.00%
Match Group, Inc. | 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%
Match Group, Inc. | Term Loan | Match Group Term Loan due November 16, 2022
Debt Instrument
Total long-term debt	$ 425,000,000			350,000,000
ANGI Homeservices
Debt Instrument
Less: unamortized debt issuance costs	2,938,000			0
Less: Current portion of long-term debt	13,750,000			0
Long-term debt, net	258,312,000			0
ANGI Homeservices | Term Loan | ANGI Homeservices Term Loan due November 1, 2022
Debt Instrument
Total long-term debt	$ 275,000,000			$ 0

LONG-TERM DEBT - SCHEDULE OF DE

LONG-TERM DEBT - SCHEDULE OF DEBT INSTRUMENT REDEMPTION (Details) - Senior Notes	12 Months Ended
	Dec. 31, 2017
6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1 | Redemption, Period One
Debt Instrument
Redemption percentage	104.781%
6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1 | Redemption, Period Two
Debt Instrument
Redemption percentage	103.188%
6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1 | Redemption, Period Three
Debt Instrument
Redemption percentage	101.594%
6.375% Senior Notes due June 1, 2024 (the Match Group 6.375% Senior Notes); interest payable each June 1 and December 1 | Redemption, Period Four
Debt Instrument
Redemption percentage	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 | Redemption, Period One
Debt Instrument
Redemption percentage	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 | Redemption, Period Two
Debt Instrument
Redemption percentage	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 | Redemption, Period Three
Debt Instrument
Redemption percentage	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 | Redemption, Period Four
Debt Instrument
Redemption percentage	100.00%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Redemption, Period One
Debt Instrument
Redemption percentage	101.583%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Redemption, Period Two
Debt Instrument
Redemption percentage	100.792%
4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15 | Redemption, Period Three
Debt Instrument
Redemption percentage	100.00%

LONG-TERM DEBT - SCHEDULE OF AG

LONG-TERM DEBT - SCHEDULE OF AGGREGATE CONTRACTUAL MATURITIES OF LONG-TERM DEBT (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2,018	$ 13,750
2,019	13,750
2,020	13,750
2,021	27,500
2,022	1,183,609
2,024	400,000
2,027	450,000
Total long-term debt	2,102,359
Less: Current portion of long-term debt	13,750	$ 20,000
Less: unamortized original issue discount and original issue premium, net	75,826
Less: unamortized debt issuance costs	33,314
Long-term debt, net	$ 1,979,469	$ 1,582,484

SHAREHOLDERS' EQUITY - NARRATIV

SHAREHOLDERS' EQUITY - NARRATIVE (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)vote$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	May 03, 2016shares
Class of Stock
Percentage of directors elected	25.00%
Class of warrant outstanding (in shares)		0
Exercise price of warrants (in dollars per share) | $ / shares	$ 0
Trade date fair value of shares acquired during period | $	$ 50,121	$ 315,250	$ 200,000
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 (in shares)	19,100,000
Treasury stock acquired during period (in shares)	700,000	6,300,000	3,000,000
Trade date fair value of shares acquired during period | $	$ 50,100	$ 315,300	$ 200,000
Number of shares authorized to be repurchased (in shares)				10,000,000
Remaining number of shares authorized to be repurchased (in shares)	8,600,000
Senior Notes | IAC
Class of Stock
Class of warrant outstanding (in shares)	3,400,000
Exercise price of warrants (in dollars per share) | $ / shares	$ 229.70

ACCUMULATED OTHER COMPREHENSI83

ACCUMULATED OTHER COMPREHENSIVE LOSS - SCHEDULE OF ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ 2,010,670,000	$ 2,215,825,000	$ 1,993,142,000
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	65,915,000	(42,088,000)	(62,069,000)
Amounts reclassified to earnings	(3,360,000)	6,937,000	(2,334,000)
Net current period other comprehensive income (loss)	62,555,000	(35,151,000)	(64,403,000)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO		(21,131,000)
Balance at end of period	2,946,823,000	2,010,670,000	2,215,825,000
Other comprehensive (loss) income before reclassifications, net of tax benefit of $0.7 million related to unrealized losses on available-for-sale securities		700,000	600,000
Tax provision (benefit) on accumulated other comprehensive income	0
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(170,149,000)	(154,645,000)	(86,848,000)
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	65,908,000	(46,943,000)	(65,606,000)
Amounts reclassified to earnings	673,000	9,850,000	(2,191,000)
Net current period other comprehensive income (loss)	66,581,000	(37,093,000)	(67,797,000)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO		(21,589,000)
Balance at end of period	(103,568,000)	(170,149,000)	(154,645,000)
Unrealized Gains On Available-For-Sale Securities
Accumulated Other Comprehensive Loss
Balance at beginning of period	4,026,000	2,542,000	(852,000)
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	7,000	4,855,000	3,537,000
Amounts reclassified to earnings	(4,033,000)	(2,913,000)	(143,000)
Net current period other comprehensive income (loss)	(4,026,000)	1,942,000	3,394,000
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO		458,000
Balance at end of period	0	4,026,000	2,542,000
Amounts reclassified to earnings, tax	3,800,000	200,000	100,000
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Loss
Balance at beginning of period	(166,123,000)	(152,103,000)	(87,700,000)
Balance at end of period	$ (103,568,000)	$ (166,123,000)	$ (152,103,000)

EARNINGS (LOSS) PER SHARE - COM

EARNINGS (LOSS) PER SHARE - COMPUTATION OF BASIC AND DILUTED EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Oct. 02, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net earnings (loss)										$ 358,008	$ (16,151)	$ 113,374
Net (earnings) loss attributable to noncontrolling interests										(53,084)	(25,129)	6,098
Impact from public subsidiaries' dilutive securities										(33,531)	0	(1,799)
Net earnings (loss) attributable to IAC shareholders		$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 102,051	$ 43,162	$ (194,775)	$ 8,282	304,924	(41,280)	119,472
Net earnings (loss) attributable to IAC shareholders										$ 271,393	$ (41,280)	$ 117,673
Weighted average basic shares outstanding (in shares)										80,089	80,045	82,944
Dilutive securities including subsidiary denominated equity, stock options and RSUs (in shares)										5,221	0	5,323
Weighted average diluted shares outstanding (in shares)										85,310	80,045	88,267
Earnings (loss) per share attributable to IAC shareholders: Basic
Basic (loss) earnings per share (USD per share)		$ 0.40	$ 2.22	$ 0.84	$ 0.34	$ 1.29	$ 0.54	$ (2.45)	$ 0.10	$ 3.81	$ (0.52)	$ 1.44
Earnings (loss) per share attributable to IAC shareholders: Diluted
Diluted (loss) earnings per share (USD per share)		$ 0.37	$ 1.79	$ 0.70	$ 0.29	$ 1.18	$ 0.49	$ (2.45)	$ 0.09	$ 3.18	$ (0.52)	$ 1.33
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (in shares)										6,900	11,300	1,200
PSUs
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (in shares)										100		600
IAC | Senior Notes
Anti-dilutive weighted average common shares
Exchange price (in dollars 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, 2017USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)$ / shares	Mar. 31, 2015USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)installmentplan$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)installment$ / sharesshares	Dec. 31, 2013	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 (in shares) | shares	2,500							2,500
Unrecognized compensation cost, net of estimated forfeitures	$ 423,200							$ 423,200
Weighted average period over which cost is expected to be recognized (in years)								2 years 6 months
Income tax benefit		$ (257,000)						$ 291,050	$ 64,934	$ (29,516)
Intrinsic value of stock options exercised								$ 164,600	$ 17,100	$ 53,000
Stock options granted in period (in shares) | shares								1,153	1,700	2,500
Weighted average grant date fair value of stock options granted (in usd per share) | $ / shares	$ 22.94				$ 15.24			$ 22.94	$ 12.34	$ 15.24
Weighted average exercise price (in usd per share) | $ / shares					84.31					84.31
Weighted average grant date fair value (in usd per share) | $ / shares					$ 12					$ 12
Number of shares required to settle vested and unvested interests at fair value (in shares) | shares								100
Cash required to settle vested and unvested interests at fair value								$ 15,200
Percentage of withholding rate								50.00%
Incremental compensation cost			$ 6,600	$ 6,800		$ 5,800			$ 7,300
Incremental compensation cost from modification recognized in year of modification								$ 700	6,300
Modification forfeitures									7,100
Incremental compensation cost from prior period modification								$ 200	600	$ 3,500
Vested equity awards settled in cash					$ 23,400
Incremental compensation cost from repurchase of fully vested equity awards					$ 7,700
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 (in years)								4 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Installments | installment								3
Percentage of installments								33.00%
Income tax benefit								$ 423,000	$ 34,800	$ 36,600
Expected volatility								29.00%	29.00%	28.00%
Risk-free interest rate								2.00%	1.20%	1.60%
Dividend yield								0.00%		2.00%
Expected term (in years)								5 years 2 months 18 days	4 years 9 months 18 days	5 years 3 months 18 days
Cash received from stock option exercises								$ 82,400	$ 25,800	$ 27,300
Employee Stock Options, Net Settled
Share-based Compensation Arrangement by Share-based Payment Award
Income tax benefit								$ 411,600	$ 63,400	$ 69,300
Market-Based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting requirement, consecutive days above price threshold (in days)										20 days
Number of annual vesting installments | installment										4
Expected volatility										27.00%
Risk-free interest rate										2.30%
Dividend yield										1.80%
Expected term (in years)										4 years
RSU's and PSU's
Share-based Compensation Arrangement by Share-based Payment Award
Weighted average grant date fair value of RSU's and PSU's granted (in usd per share) | $ / shares								$ 90.04	$ 46.92	$ 67.71
Fair value of RSU's and PSU's that vested during the period								$ 32,500	$ 13,500	$ 16,800
RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)								3 years
Weighted average grant date fair value of RSU's and PSU's granted (in usd per share) | $ / shares								$ 100.54
Vesting period one | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								25.00%
Vesting period one | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								33.00%
Vesting period two | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								25.00%
Vesting period two | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								33.00%
Vesting period three | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								25.00%
Vesting period three | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								33.00%
Vesting period four | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting rights, percentage								25.00%
IAC
Share-based Compensation Arrangement by Share-based Payment Award
Common stock, issued shares (in shares) | shares	800							800					2,000
Match Group
Share-based Compensation Arrangement by Share-based Payment Award
Common stock, issued shares (in shares) | shares	3,300							3,300					11,300
Cash payments made to cover withholding taxes and exercise of awards								$ 520,000
Cash payments made to cover withholding taxes								$ 102,400
Vested equity awards settled in cash		$ 33,900		$ 13,400
ANGI Homeservices
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares required to settle vested and unvested interests at fair value (in shares) | shares	1,400
Cash required to settle vested and unvested interests at fair value	$ 171,300
Common stock, issued shares (in shares) | shares	16,400							16,400
Incremental compensation cost								$ 217,700
Incremental compensation cost from modification recognized in year of modification								$ 93,400
Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award
Incremental compensation cost from modification recognized in year of modification							$ 100

STOCK-BASED COMPENSATION - SCHE

STOCK-BASED COMPENSATION - SCHEDULE OF CHANGES IN OUTSTANDING STOCK OPTIONS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Balance at beginning of period (in shares)	8,058
Granted (in shares)	1,153	1,700	2,500
Exercised (in shares)	(2,443)
Forfeited (in shares)	(179)
Expired (in shares)	(3)
Balance at end of period (in shares)	6,586	8,058
Options exercisable (in shares)	2,920
Weighted Average Exercise Price
Balance at beginning of period (in usd per share)	$ 52.41
Granted (in usd per share)	76.62
Exercised (in usd per share)	41.30
Forfeited (in usd per share)	59.34
Expired (in usd per share)	56.31
Balance at end of period (in usd per share)	60.57	$ 52.41
Options exercisable (in usd per share)	$ 55.28
Weighted Average Remaining Contractual Term (In Years)
Balance at end of period (in years)	7 years
Options exercisable (in years)	5 years 7 months 6 days
Aggregate Intrinsic Value
Balance at end of period	$ 406,527
Options exercisable	$ 195,677

STOCK-BASED COMPENSATION - SC87

STOCK-BASED COMPENSATION - SCHEDULE OF INFORMATION FOR STOCK OPTIONS OUTSTANDING AND EXERCISABLE (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Options Outstanding
Options outstanding (in shares) | shares	6,586
Weighted- Average Remaining Contractual Life in Years	7 years
Weighted-average exercise price (in usd per share)	$ 60.57
Options Exercisable
Options exercisable (in shares) | shares	2,920
Weighted- Average Remaining Contractual Life in Years	5 years 7 months 6 days
Weighted-average exercise price (in usd per share)	$ 55.28
$10.01 to $20.00
Options Outstanding
Options outstanding (in shares) | shares	38
Weighted- Average Remaining Contractual Life in Years	10 months 24 days
Weighted-average exercise price (in usd per share)	$ 16.67
Options Exercisable
Options exercisable (in shares) | shares	38
Weighted- Average Remaining Contractual Life in Years	10 months 24 days
Weighted-average exercise price (in usd per share)	$ 16.67
$20.01 to $30.00
Options Outstanding
Options outstanding (in shares) | shares	66
Weighted- Average Remaining Contractual Life in Years	1 year 6 months
Weighted-average exercise price (in usd per share)	$ 21.15
Options Exercisable
Options exercisable (in shares) | shares	66
Weighted- Average Remaining Contractual Life in Years	1 year 6 months
Weighted-average exercise price (in usd per share)	$ 21.15
$30.01 to $40.00
Options Outstanding
Options outstanding (in shares) | shares	415
Weighted- Average Remaining Contractual Life in Years	3 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 32.31
Options Exercisable
Options exercisable (in shares) | shares	415
Weighted- Average Remaining Contractual Life in Years	3 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 32.31
$40.01 to $50.00
Options Outstanding
Options outstanding (in shares) | shares	1,862
Weighted- Average Remaining Contractual Life in Years	6 years 9 months 18 days
Weighted-average exercise price (in usd per share)	$ 43.42
Options Exercisable
Options exercisable (in shares) | shares	870
Weighted- Average Remaining Contractual Life in Years	5 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 44.86
$50.01 to $60.00
Options Outstanding
Options outstanding (in shares) | shares	263
Weighted- Average Remaining Contractual Life in Years	4 years
Weighted-average exercise price (in usd per share)	$ 59.47
Options Exercisable
Options exercisable (in shares) | shares	259
Weighted- Average Remaining Contractual Life in Years	4 years
Weighted-average exercise price (in usd per share)	$ 59.48
$60.01 to $70.00
Options Outstanding
Options outstanding (in shares) | shares	1,474
Weighted- Average Remaining Contractual Life in Years	7 years 2 months 12 days
Weighted-average exercise price (in usd per share)	$ 65
Options Exercisable
Options exercisable (in shares) | shares	615
Weighted- Average Remaining Contractual Life in Years	6 years 10 months 24 days
Weighted-average exercise price (in usd per share)	$ 65.49
$70.01 to $80.00
Options Outstanding
Options outstanding (in shares) | shares	1,952
Weighted- Average Remaining Contractual Life in Years	8 years 4 months 24 days
Weighted-average exercise price (in usd per share)	$ 75.30
Options Exercisable
Options exercisable (in shares) | shares	407
Weighted- Average Remaining Contractual Life in Years	7 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 74.16
$80.01 to $90.00
Options Outstanding
Options outstanding (in shares) | shares	500
Weighted- Average Remaining Contractual Life in Years	7 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 84.31
Options Exercisable
Options exercisable (in shares) | shares	250
Weighted- Average Remaining Contractual Life in Years	7 years 3 months 18 days
Weighted-average exercise price (in usd per share)	$ 84.31
Greater than $90.01
Options Outstanding
Options outstanding (in shares) | shares	16
Weighted- Average Remaining Contractual Life in Years	9 years 10 months 24 days
Weighted-average exercise price (in usd per share)	$ 125.06
Options Exercisable
Options exercisable (in shares) | shares	0
Weighted- Average Remaining Contractual Life in Years	0 years
Weighted-average exercise price (in usd per share)	$ 0
Exercise price range, lower limit (in usd per share)	90.01
Minimum | $10.01 to $20.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	10.01
Minimum | $20.01 to $30.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	20.01
Minimum | $30.01 to $40.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	30.01
Minimum | $40.01 to $50.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	40.01
Minimum | $50.01 to $60.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	50.01
Minimum | $60.01 to $70.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	60.01
Minimum | $70.01 to $80.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	70.01
Minimum | $80.01 to $90.00
Options Exercisable
Exercise price range, lower limit (in usd per share)	80.01
Maximum | $10.01 to $20.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	20
Maximum | $20.01 to $30.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	30
Maximum | $30.01 to $40.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	40
Maximum | $40.01 to $50.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	50
Maximum | $50.01 to $60.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	60
Maximum | $60.01 to $70.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	70
Maximum | $70.01 to $80.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	80
Maximum | $80.01 to $90.00
Options Exercisable
Exercise price range, upper limit (in usd per share)	$ 90

STOCK-BASED COMPENSATION - SC88

STOCK-BASED COMPENSATION - SCHEDULE OF WEIGHTED AVERAGE ASSUMPTIONS (Details) - Stock Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Expected volatility	29.00%	29.00%	28.00%
Risk-free interest rate	2.00%	1.20%	1.60%
Expected term (in years)	5 years 2 months 18 days	4 years 9 months 18 days	5 years 3 months 18 days
Dividend yield	0.00%		2.00%

STOCK-BASED COMPENSATION - SC89

STOCK-BASED COMPENSATION - SCHEDULE OF OUTSTANDING UNVESTED RSUs AND PSUs (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
RSUs
Number of Shares
Balance at beginning of the period (in shares) | shares	526
Granted (in shares) | shares	174
Vested (in shares) | shares	(340)
Balance at end of the period (in shares) | shares	360
Weighted Average Grant Date Fair Value
Balance at beginning of the period (in usd per share) | $ / shares	$ 57.41
Granted (in usd per share) | $ / shares	100.54
Vested (in usd per share) | $ / shares	54.66
Balance at end of the period (in usd per share) | $ / shares	$ 80.81
Vesting period (in years)	3 years
PSUs
Number of Shares
Balance at beginning of the period (in shares) | shares	0
Granted (in shares) | shares	130
Vested (in shares) | shares	0
Forfeited (in shares) | shares	0
Balance at end of the period (in shares) | shares	130
Weighted Average Grant Date Fair Value
Balance at beginning of the period (in usd per share) | $ / shares	$ 0
Granted (in usd per share) | $ / shares	76
Vested (in usd per share) | $ / shares	0
Forfeited (in usd per share) | $ / shares	0
Balance at end of the period (in usd per share) | $ / shares	$ 76

SEGMENT INFORMATION - SCHEDULE

SEGMENT INFORMATION - SCHEDULE OF SEGMENT REPORTING INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933
Operating income (loss)	94,360	$ (18,589)	$ 75,635	$ 37,060	112,820	$ 85,584	$ (252,446)	$ 21,417	188,466	(32,625)	179,588
Adjusted EBITDA									575,293	501,219	485,790
Segment Assets	2,263,516				2,057,611				2,263,516	2,057,611
Capital expenditures									75,523	78,039	62,049
Operating Segments | Match Group, Inc.
Segment Reporting Information [Line Items]
Operating income (loss)									360,517	315,549	212,981
Adjusted EBITDA									468,941	403,380	284,554
Segment Assets	467,338				422,509				467,338	422,509
Capital expenditures									28,833	46,098	25,246
Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue									736,386	498,890	361,201
Operating income (loss)									(149,176)	25,363	(1,568)
Adjusted EBITDA									37,858	45,851	16,713
Segment Assets	264,450				74,106				264,450	74,106
Capital expenditures									26,837	16,660	10,170
Operating Segments | Video
Segment Reporting Information [Line Items]
Revenue									276,994	228,649	213,317
Operating income (loss)									(35,659)	(27,656)	(38,756)
Adjusted EBITDA									(30,446)	(21,247)	(38,384)
Segment Assets	129,855				225,519				129,855	225,519
Capital expenditures									400	2,508	2,466
Operating Segments | Applications
Segment Reporting Information [Line Items]
Revenue									577,998	604,140	760,748
Operating income (loss)									130,176	109,663	175,145
Adjusted EBITDA									136,757	132,276	184,258
Segment Assets	345,532				98,460				345,532	98,460
Capital expenditures									227	1,196	4,681
Operating Segments | Publishing
Segment Reporting Information [Line Items]
Revenue									361,837	407,313	691,686
Operating income (loss)									15,670	(334,417)	(26,692)
Adjusted EBITDA									31,470	(7,571)	87,788
Segment Assets	182,949				398,958				182,949	398,958
Capital expenditures									850	2,093	6,283
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenue									23,980	283,365	294,821
Operating income (loss)									(5,621)	(11,678)	(28,611)
Adjusted EBITDA									(1,532)	1,802	4,734
Segment Assets	0				15,372				0	15,372
Capital expenditures									536	5,712	7,085
Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue									(617)	(585)	(545)
Corporate
Segment Reporting Information [Line Items]
Operating income (loss)									(127,441)	(109,449)	(112,911)
Adjusted EBITDA									(67,755)	(53,272)	(53,873)
Segment Assets	$ 873,392				$ 822,687				873,392	822,687
Capital expenditures									$ 17,840	$ 3,772	$ 6,118

SEGMENT INFORMATION - SCHEDUL91

SEGMENT INFORMATION - SCHEDULE OF REVENUE DISAGGREGATED BY SERVICE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Service revenue									$ 3,302,937	$ 2,967,474	$ 3,077,080
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	3,307,239	3,139,882	3,230,933
Operating Segments | Match Group
Segment Reporting Information [Line Items]
Service revenue									1,281,249	1,067,364	866,583
Indirect revenue (principally advertising revenue)									49,412	50,746	43,122
Revenue									1,330,661	1,118,110	909,705
Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Consumer connection revenue									521,481	382,466	269,309
Membership subscription revenue									56,135	43,573	24,164
Other revenue									3,798	2,827	3,423
Revenue									736,386	498,890	361,201
Operating Segments | Applications
Segment Reporting Information [Line Items]
Advertising									515,405	552,410	728,501
Subscription (including downloadable app fees) and other									62,593	51,730	32,247
Revenue									577,998	604,140	760,748
Operating Segments | Publishing
Segment Reporting Information [Line Items]
Other revenue									3,365	2,282	6,246
Advertising									358,472	405,031	685,440
Revenue									361,837	407,313	691,686
North America | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Marketplace revenue									581,414	428,866	296,896
Advertising and other revenue									97,483	32,981	32,971
Revenue									678,897	461,847	329,867
Europe | Operating Segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Service revenue									57,489	37,043	31,334
Consumer connection revenue									40,009	28,124	23,298
Membership subscription revenue									16,596	7,936	6,921
Advertising and other revenue									$ 884	$ 983	$ 1,115

SEGMENT INFORMATION - SCHEDUL92

SEGMENT INFORMATION - SCHEDULE OF REVENUE AND LONG-LIVED ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue and Long-lived Assets by Geography
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933
Long-lived assets (excluding goodwill and intangible assets)	315,170				306,248				315,170	306,248
United States
Revenue and Long-lived Assets by Geography
Revenue									2,323,050	2,318,976	2,376,035
Long-lived assets (excluding goodwill and intangible assets)	286,541				281,725				286,541	281,725
All Other Countries
Revenue and Long-lived Assets by Geography
Revenue									984,189	820,906	$ 854,898
Long-lived assets (excluding goodwill and intangible assets)	$ 28,629				$ 24,523				$ 28,629	$ 24,523

SEGMENT INFORMATION - SCHEDUL93

SEGMENT INFORMATION - SCHEDULE OF RECONCILIATION OF ADJUSTED EBITDA TO OPERATING INCOME (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)	$ 94,360	$ (18,589)	$ 75,635	$ 37,060	$ 112,820	$ 85,584	$ (252,446)	$ 21,417	$ 188,466	$ (32,625)	$ 179,588
Stock-based compensation expense									264,618	104,820	105,450
Depreciation									74,265	71,676	62,205
Amortization of intangibles									42,143	79,426	139,952
Acquisition-related Contingent Consideration Fair Value Adjustments									5,801	2,555	(15,461)
Adjusted EBITDA									575,293	501,219	485,790
Goodwill Impairment									0	275,367	14,056
Interest expense									(105,295)	(109,110)	(73,636)
Other expense, net									(16,213)	60,650	36,938
Earnings (loss) before income taxes									66,958	(81,085)	142,890
Income tax benefit		(257,000)							291,050	64,934	(29,516)
(Loss) earnings from continuing operations									358,008	(16,151)	113,374
Net earnings (loss)	23,349	225,639	80,557	28,463	114,117	52,340	(190,542)	7,934	358,008	(16,151)	113,374
Net (earnings) loss attributable to noncontrolling interests									(53,084)	(25,129)	6,098
Net earnings (loss) attributable to IAC shareholders	$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 102,051	$ 43,162	(194,775)	$ 8,282	304,924	(41,280)	119,472
Match Group
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment										0
ANGI Homeservices
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment										0
Video
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment										0
Applications
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment										0
Publishing
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment							$ (275,400)			275,367
Other
Segment Reporting, Other Significant Reconciling Item
Goodwill Impairment										0
Operating Segments | Match Group
Segment Reporting, Other Significant Reconciling Item
Stock-based compensation expense									69,090	52,370	49,401
Depreciation									32,613	27,726	19,791
Amortization of intangibles									1,468	16,932	13,437
Acquisition-related Contingent Consideration Fair Value Adjustments									5,253	(9,197)	(11,056)
Goodwill Impairment										0	0
Operating Segments | ANGI Homeservices
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									(149,176)	25,363	(1,568)
Stock-based compensation expense									149,230	8,916	7,853
Depreciation									14,543	8,419	6,593
Amortization of intangibles									23,261	3,153	3,835
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									37,858	45,851	16,713
Goodwill Impairment										0	0
Operating Segments | Video
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									(35,659)	(27,656)	(38,756)
Stock-based compensation expense									401	640	360
Depreciation									2,167	1,785	1,091
Amortization of intangibles									2,645	4,176	1,558
Acquisition-related Contingent Consideration Fair Value Adjustments									0	(192)	(2,637)
Adjusted EBITDA									(30,446)	(21,247)	(38,384)
Goodwill Impairment										0	0
Operating Segments | Applications
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									130,176	109,663	175,145
Stock-based compensation expense									0	0	0
Depreciation									3,863	5,095	4,617
Amortization of intangibles									2,170	5,483	6,264
Acquisition-related Contingent Consideration Fair Value Adjustments									548	12,035	(1,768)
Adjusted EBITDA									136,757	132,276	184,258
Goodwill Impairment										0	0
Operating Segments | Publishing
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									15,670	(334,417)	(26,692)
Stock-based compensation expense									0	0	0
Depreciation									4,725	8,531	9,577
Amortization of intangibles									11,075	42,948	104,903
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									31,470	(7,571)	87,788
Goodwill Impairment										275,367	0
Operating Segments | Other
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									(5,621)	(11,678)	(28,611)
Stock-based compensation expense									1,729	618	682
Depreciation									836	6,219	8,652
Amortization of intangibles									1,524	6,734	9,955
Acquisition-related Contingent Consideration Fair Value Adjustments									0	(91)	0
Adjusted EBITDA									(1,532)	1,802	4,734
Goodwill Impairment										0	14,056
Corporate
Segment Reporting, Other Significant Reconciling Item
Operating income (loss)									(127,441)	(109,449)	(112,911)
Stock-based compensation expense									44,168	42,276	47,154
Depreciation									15,518	13,901	11,884
Amortization of intangibles									0	0	0
Acquisition-related Contingent Consideration Fair Value Adjustments									0	0	0
Adjusted EBITDA									$ (67,755)	(53,272)	(53,873)
Goodwill Impairment										$ 0	$ 0

SEGMENT INFORMATION - SCHEDUL94

SEGMENT INFORMATION - SCHEDULE OF RECONCILIATION OF SEGMENT ASSETS TO TOTAL ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item
Segment Assets	$ 2,263,516	$ 2,057,611
Long-lived assets (excluding goodwill and intangible assets)	315,170	306,248
Goodwill	2,559,066	1,924,052	$ 2,245,364
Indefinite-Lived Intangible Assets	459,143	320,645
Definite-Lived Intangible Assets, Net	204,594	34,806
Assets before deferred tax assets	5,801,489	4,643,362
Add: Deferred tax assets	66,321	2,511
TOTAL ASSETS	5,867,810	4,645,873
ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Goodwill	768,317	170,611	150,251
Video
Segment Reporting, Asset Reconciling Item
Goodwill	95,608	25,239	15,590
Applications
Segment Reporting, Asset Reconciling Item
Goodwill	447,242	447,242	447,242
Publishing
Segment Reporting, Asset Reconciling Item
Goodwill		0	277,192
Other
Segment Reporting, Asset Reconciling Item
Goodwill	0	74,422	$ 136,482
Operating Segments | Match Group, Inc.
Segment Reporting, Asset Reconciling Item
Segment Assets	467,338	422,509
Long-lived assets (excluding goodwill and intangible assets)	61,620	62,954
Goodwill	1,247,899	1,206,538
Indefinite-Lived Intangible Assets	228,296	214,461
Definite-Lived Intangible Assets, Net	2,049	3,221
Assets before deferred tax assets	2,007,202	1,909,683
Operating Segments | ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Segment Assets	264,450	74,106
Long-lived assets (excluding goodwill and intangible assets)	53,292	23,645
Goodwill	768,317	170,611
Indefinite-Lived Intangible Assets	153,447	4,884
Definite-Lived Intangible Assets, Net	175,124	5,908
Assets before deferred tax assets	1,414,630	279,154
Operating Segments | Video
Segment Reporting, Asset Reconciling Item
Segment Assets	129,855	225,519
Long-lived assets (excluding goodwill and intangible assets)	3,076	4,750
Goodwill	95,608	25,239
Indefinite-Lived Intangible Assets	1,800	1,800
Definite-Lived Intangible Assets, Net	23,322	4,167
Assets before deferred tax assets	253,661	261,475
Operating Segments | Applications
Segment Reporting, Asset Reconciling Item
Segment Assets	345,532	98,460
Long-lived assets (excluding goodwill and intangible assets)	7,004	10,559
Goodwill	447,242	447,242
Indefinite-Lived Intangible Assets	60,600	60,600
Definite-Lived Intangible Assets, Net	847	2,481
Assets before deferred tax assets	861,225	619,342
Operating Segments | Publishing
Segment Reporting, Asset Reconciling Item
Segment Assets	182,949	398,958
Long-lived assets (excluding goodwill and intangible assets)	5,350	10,696
Goodwill	0	0
Indefinite-Lived Intangible Assets	15,000	15,000
Definite-Lived Intangible Assets, Net	3,252	11,441
Assets before deferred tax assets	206,551	436,095
Operating Segments | Other
Segment Reporting, Asset Reconciling Item
Segment Assets	0	15,372
Long-lived assets (excluding goodwill and intangible assets)	0	6,774
Goodwill	0	74,422
Indefinite-Lived Intangible Assets	0	23,900
Definite-Lived Intangible Assets, Net	0	7,588
Assets before deferred tax assets	0	128,056
Corporate
Segment Reporting, Asset Reconciling Item
Segment Assets	873,392	822,687
Long-lived assets (excluding goodwill and intangible assets)	184,828	186,870
Goodwill	0	0
Indefinite-Lived Intangible Assets	0	0
Definite-Lived Intangible Assets, Net	0	0
Assets before deferred tax assets	$ 1,058,220	$ 1,009,557

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - SCHEDULE OF FUTURE MINIMUM PAYMENTS UNDER OPERATING LEASE AGREEMENTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Future Minimum Payments Under Operating Lease Agreements
2,018	$ 38,339
2,019	36,996
2,020	30,594
2,021	23,253
2,022	19,688
Thereafter	211,649
Total	360,519
Expenses charged to operations under operating lease agreements	$ 37,900	$ 50,800	$ 39,400
Period of most significant operating leases (in years)	77 years
Percentage of most significant operating leases	48.00%

COMMITMENTS AND CONTINGENCIES96

COMMITMENTS AND CONTINGENCIES - SCHEDULE OF COMMERCIAL COMMITMENTS OUTSTANDING (Details) $ in Thousands	Dec. 31, 2017USD ($)
Other Commitments
Less Than 1 Year	$ 22,570
1-3 Years	10,887
3-5 Years	0
More Than 5 Years	1,939
Total Amounts Committed	35,396
Purchase obligations
Other Commitments
Less Than 1 Year	21,994
1-3 Years	10,816
3-5 Years	0
More Than 5 Years	0
Total Amounts Committed	32,810
Letters of credit and surety bonds
Other Commitments
Less Than 1 Year	576
1-3 Years	71
3-5 Years	0
More Than 5 Years	1,939
Total Amounts Committed	$ 2,586

SUPPLEMENTAL CASH FLOW INFORM97

SUPPLEMENTAL CASH FLOW INFORMATION - SCHEDULE OF SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION (Details) - USD ($) shares in Thousands, $ in Thousands	Nov. 16, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 04, 2017	Sep. 29, 2017
Supplemental Cash Flow Information [Abstract]
Fair value of contingent consideration liabilities			$ 200	$ 27,400
Cash paid (received) during the year for:
Interest		$ 92,461	107,360	51,666
Income tax payments		35,598	69,103	70,762
Income tax refunds		$ (42,025)	$ (23,877)	$ (5,619)
Common Stock
Supplemental Cash Flow Information [Abstract]
Common stock, issued shares (in shares)		260,624	255,672			61,300
Common stock		$ 261	$ 256			$ 763,700
Match Group, Inc. | 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%
Match Group, Inc. | Senior Notes | Match Group Senior Notes
Debt Instrument
Stated interest rate (as a percent)	6.75%	6.75%			6.75%
Match Group, Inc. | Senior Notes | Debt Conversion, Private Exchange Offer upon IPO | 4.75% Senior Notes due December 15, 2022 (the 4.75% Senior Notes); interest payable each June 15 and December 15
Debt Instrument
Debt instrument exchanged amount, original debt	$ 445,300
Debt instrument exchanged amount, new debt	$ 445,200

RELATED PARTY TRANSACTIONS - NA

RELATED PARTY TRANSACTIONS - NARRATIVE (Details) shares in Millions, $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)shares	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)aircraftshares	Dec. 31, 2016USD ($)shares	Sep. 29, 2017USD ($)intercompany_note
Services Agreement
Related Party Transaction [Line Items]
Payments received from related parties				$ 0.4
Amount payable, related parties		$ 2		$ 2
Match Group | Employee Matters Agreement
Related Party Transaction [Line Items]
Shares received from related party pursuant to employee matters agreement (in shares) | shares		0.4		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				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				0.6	0.4
Match Group | Services Agreement
Related Party Transaction [Line Items]
Payments received from related parties	$ 0.7	$ 1.7		$ 9.9	$ 11.8
Match Group | Leased Office Space
Related Party Transaction [Line Items]
Expenses from transactions with related parties	$ 0.3			5.1	4.3
Match Group | Tax Sharing Agreement
Related Party Transaction [Line Items]
Payments received from related parties				10.9	19.9
Amounts due to related party				7.3	$ 9
Match Group | Net Operating Loss Sold
Related Party Transaction [Line Items]
Expenses from transactions with related parties				$ 0.9
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]
Notes receivable						$ 61.5
ANGI Homeservices | Working Capital Intercompany Note
Related Party Transaction [Line Items]
Notes receivable						$ 15
Other Affiliates
Related Party Transaction [Line Items]
Ownership interest held by each of the Company and Expedia in aircraft (as a percent)		50.00%		50.00%
Number of aircraft operated | aircraft				3
IAC's total purchase price and refurbish costs in aircraft			$ 17.4
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%		50.00%

BENEFIT PLANS - NARRATIVE (Deta

BENEFIT PLANS - NARRATIVE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	$ 11.1	$ 10	$ 9.1
All Other Countries
Defined Contribution Plan Disclosure
Defined contribution plan contributions	$ 2.5	$ 2.1	$ 2.5

CONSOLIDATED FINANCIAL STATE100

CONSOLIDATED FINANCIAL STATEMENT DETAILS - NARRATIVE (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 04, 2017	Nov. 16, 2015
Term Loan | Match Group, Inc. | Match Group Term Loan due November 16, 2022
Additional consolidated financial statement details
Repayment of debt				$ 440
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)	4.875%		4.875%	4.875%
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%	4.75%
Senior Notes | Match Group, Inc. | 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%	6.75%
Other Income (Expense)
Additional consolidated financial statement details
Foreign currency exchange gain (loss)			$ (16.8)	$ 34.4	$ 5.4
Cost of repricing debt			15.4
Gain (loss) on mark-to-market adjustment			(13)	(2.5)	(2.3)
Gain on sale of long-term investments			34.9	3.6
Interest income			11.4	5.1	4.3
Write-off of proportionate share of original issue discount and deferred financing costs				12.1
Proceeds from sale of real estate					34.3
Other-than-temporary impairment on cost method investments					$ 6.7
Other Income (Expense) | Senior Notes
Additional consolidated financial statement details
Loss on redemption and repurchase of 2012 and 2013 Senior Notes				3.6
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			(12.2)
Gain on sale of business			$ (1.2)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | PriceRunner
Additional consolidated financial statement details
Gain on sale of business		$ 11.9
Disposal Group, Disposed of by Sale, Not Discontinued Operations | PriceRunner | Other Income (Expense)
Additional consolidated financial statement details
Gain on sale of business				12
Disposal Group, Disposed of by Sale, Not Discontinued Operations | ShoeBuy
Additional consolidated financial statement details
Gain on sale of business	$ 37.5
Disposal Group, Disposed of by Sale, Not Discontinued Operations | ShoeBuy | Other Income (Expense)
Additional consolidated financial statement details
Gain on sale of business				37.5
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				10.7
Gain on sale of business				$ (3.8)

CONSOLIDATED FINANCIAL STATE101

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other current assets:
Prepaid expenses	$ 49,350	$ 37,665
Income taxes receivable	33,239	41,352
Capitalized downloadable search toolbar costs, net	31,588	28,737
Production costs	18,570	39,763
Other	52,627	56,551
Other current assets	$ 185,374	$ 204,068

CONSOLIDATED FINANCIAL STATE102

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF PROPERTY AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	$ 586,981	$ 635,738
Accumulated depreciation and amortization	(271,811)	(329,490)
Property and equipment, net of accumulated depreciation and amortization	315,170	306,248
Buildings and leasehold improvements
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	252,511	247,563
Computer equipment and capitalized software
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	218,529	275,455
Furniture and other equipment
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	88,930	94,555
Projects in progress
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	19,094	13,048
Land
Property and equipment, net of accumulated depreciation and amortization:
Property and equipment, gross	$ 7,917	$ 5,117

CONSOLIDATED FINANCIAL STATE103

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued expenses and other current liabilities:
Accrued employee compensation and benefits	$ 108,431	$ 106,301
Accrued advertising expense	96,445	68,916
Other	162,048	169,693
Accrued expenses and other current liabilities	$ 366,924	$ 344,910

CONSOLIDATED FINANCIAL STATE104

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Service revenue									$ 3,302,937	$ 2,967,474	$ 3,077,080
Product revenue									4,302	172,408	153,853
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933

CONSOLIDATED FINANCIAL STATE105

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cost of revenue:
Cost of service revenue									$ 647,226	$ 617,058	$ 652,137
Cost of product revenue									3,782	138,672	126,024
Cost of revenue	$ 199,727	$ 166,290	$ 139,033	$ 145,958	$ 212,468	$ 179,131	$ 170,397	$ 193,734	$ 651,008	$ 755,730	$ 778,161

CONSOLIDATED FINANCIAL STATE106

CONSOLIDATED FINANCIAL STATEMENT DETAILS - SCHEDULE OF OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other income (expense), net:
Other (expense) income, net	$ (16,213)	$ 60,650	$ 36,938

TRANSACTION AND INTEGRATION 107

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION - NARRATIVE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Stock-based compensation expense	$ 264,618	$ 104,820	$ 105,450
ANGI Homeservices
Business Acquisition [Line Items]
Transaction and integration related costs	44,101
Write-off due to deferred revenue	7,800
Stock-based compensation expense	$ 122,066

TRANSACTION AND INTEGRATION 108

TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION - SUMMARY (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Stock-based compensation expense	$ 264,618	$ 104,820	$ 105,450
Cost of revenue
Business Acquisition [Line Items]
Stock-based compensation expense	1,881	2,305	1,210
Selling and marketing expense
Business Acquisition [Line Items]
Stock-based compensation expense	31,318	6,000	10,186
General and administrative expense
Business Acquisition [Line Items]
Stock-based compensation expense	192,957	77,151	82,798
Product development expense
Business Acquisition [Line Items]
Stock-based compensation expense	38,462	$ 19,364	$ 11,256
ANGI Homeservices
Business Acquisition [Line Items]
Transaction and integration related costs	44,101
Stock-based compensation expense	122,066
Total	166,167
Charges incurred	44,101
Payments made	(35,621)
Accrual as of December 31	8,480
ANGI Homeservices | Cost of revenue
Business Acquisition [Line Items]
Transaction and integration related costs	0
Stock-based compensation expense	0
Total	0
ANGI Homeservices | Selling and marketing expense
Business Acquisition [Line Items]
Transaction and integration related costs	7,430
Stock-based compensation expense	24,416
Total	31,846
ANGI Homeservices | General and administrative expense
Business Acquisition [Line Items]
Transaction and integration related costs	36,120
Stock-based compensation expense	83,420
Total	119,540
ANGI Homeservices | Product development expense
Business Acquisition [Line Items]
Transaction and integration related costs	551
Stock-based compensation expense	14,230
Total	$ 14,781

GUARANTOR AND NON-GUARANTOR 109

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, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (as a percent)	4.75%	4.75%
Percentage of voting interests acquired	100.00%

GUARANTOR AND NON-GUARANTOR 110

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - CONDENSED BALANCE SHEET (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Balance Sheet
Cash and cash equivalents	$ 1,630,809	$ 1,329,187	$ 1,481,447	$ 990,405
Marketable securities	4,995	89,342
Accounts receivable, net of allowance	304,027	220,138
Other current assets	185,374	204,068
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization	315,170	306,248
Goodwill	2,559,066	1,924,052	2,245,364
Intangible assets, net of accumulated amortization	663,737	355,451
Investment in subsidiaries	0	0
Other non-current assets	204,632	217,387
TOTAL ASSETS	5,867,810	4,645,873
Current portion of long-term debt	13,750	20,000
Accounts payable, trade	76,571	62,863
Other current liabilities	709,407	630,525
Long-term debt, net	1,979,469	1,582,484
Income taxes payable	25,624	33,528
Intercompany liabilities	0	0
Other long-term liabilities	73,299	272,976
Redeemable noncontrolling interests	42,867	32,827
IAC shareholders' equity	2,430,028	1,869,222
Noncontrolling interests	516,795	141,448
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,867,810	4,645,873
Eliminations
Condensed Balance Sheet
Cash and cash equivalents	0	0	0
Marketable securities	0	0
Accounts receivable, net of allowance	0	0
Other current assets	0	0
Intercompany receivables	(668,703)	(1,774,801)
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	(2,631,002)	(4,157,624)
Other non-current assets	(132,435)	(115,473)
TOTAL ASSETS	(3,432,140)	(6,047,898)
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	(216)
Intercompany liabilities	(668,703)	(1,774,801)
Other long-term liabilities	(132,435)	(115,257)
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(2,631,002)	(4,157,624)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(3,432,140)	(6,047,898)
IAC
Condensed Balance Sheet
Cash and cash equivalents	585,639	553,643
Current portion of long-term debt	0	20,000
Long-term debt, net	468,461	405,991
IAC | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	585,639	553,643	1,074,658	762,689
Marketable securities	4,995	89,342
Accounts receivable, net of allowance	31	0
Other current assets	49,159	71,152
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization	2,811	4,350
Goodwill	0	0
Intangible assets, net of accumulated amortization	0	0
Investment in subsidiaries	2,076,004	3,659,570
Other non-current assets	170,073	52,228
TOTAL ASSETS	2,888,712	4,430,285
Current portion of long-term debt	0	20,000
Accounts payable, trade	5,163	2,697
Other current liabilities	29,489	42,160
Long-term debt, net	34,572	405,991
Income taxes payable	16	0
Intercompany liabilities	388,933	1,774,801
Other long-term liabilities	511	315,414
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	2,430,028	1,869,222
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,888,712	4,430,285
Guarantor Subsidiaries
Condensed Balance Sheet
Cash and cash equivalents	0	0
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net of allowance	109,289	77,335
Other current assets	33,387	48,349
Intercompany receivables	668,703	565,013
Property and equipment, net of accumulated depreciation and amortization	174,323	199,343
Goodwill	412,010	412,010
Intangible assets, net of accumulated amortization	74,852	83,179
Investment in subsidiaries	554,998	498,054
Other non-current assets	87,306	118,624
TOTAL ASSETS	2,114,868	2,001,907
Current portion of long-term debt	0	0
Accounts payable, trade	30,469	29,867
Other current liabilities	88,050	84,827
Long-term debt, net	0	0
Income taxes payable	1,605	3,470
Intercompany liabilities	0	0
Other long-term liabilities	18,613	21,002
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	1,976,131	1,862,741
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,114,868	2,001,907
Non-Guarantor Subsidiaries
Condensed Balance Sheet
Cash and cash equivalents	1,045,170	775,544
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Balance Sheet
Cash and cash equivalents	1,045,170	775,544	$ 406,789	$ 227,716
Marketable securities	0	0
Accounts receivable, net of allowance	194,707	142,803
Other current assets	102,828	84,567
Intercompany receivables	0	1,209,788
Property and equipment, net of accumulated depreciation and amortization	138,036	102,555
Goodwill	2,147,056	1,512,042
Intangible assets, net of accumulated amortization	588,885	272,272
Investment in subsidiaries	0	0
Other non-current assets	79,688	162,008
TOTAL ASSETS	4,296,370	4,261,579
Current portion of long-term debt	13,750	0
Accounts payable, trade	40,939	30,299
Other current liabilities	591,868	503,538
Long-term debt, net	1,944,897	1,176,493
Income taxes payable	24,003	30,274
Intercompany liabilities	279,770	0
Other long-term liabilities	186,610	51,817
Redeemable noncontrolling interests	42,867	32,827
IAC shareholders' equity	654,871	2,294,883
Noncontrolling interests	516,795	141,448
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 4,296,370	$ 4,261,579

GUARANTOR AND NON-GUARANTOR 111

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - CONDENSED STATEMENT OF OPERATIONS (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Statements of Operations
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	199,727	166,290	139,033	145,958	212,468	179,131	170,397	193,734	651,008	755,730	778,161
Selling and marketing expense									1,381,221	1,247,097	1,348,293
General and administrative expense									719,257	530,446	512,055
Product development expense									250,879	212,765	196,623
Depreciation									74,265	71,676	62,205
Amortization of intangibles									42,143	79,426	139,952
Goodwill impairment									0	275,367	14,056
Total operating costs and expenses									3,118,773	3,172,507	3,051,345
Operating income (loss)	94,360	(18,589)	75,635	37,060	112,820	85,584	(252,446)	21,417	188,466	(32,625)	179,588
Equity in earnings of unconsolidated affiliates									0	0	0
Interest expense									(105,295)	(109,110)	(73,636)
Other (expense) income, net									(16,213)	60,650	36,938
Earnings (loss) before income taxes									66,958	(81,085)	142,890
Income tax benefit (provision)		(257,000)							291,050	64,934	(29,516)
(Loss) earnings from continuing operations									358,008	(16,151)	113,374
Net earnings (loss)	23,349	225,639	80,557	28,463	114,117	52,340	(190,542)	7,934	358,008	(16,151)	113,374
Net (earnings) loss attributable to noncontrolling interests									(53,084)	(25,129)	6,098
Net earnings (loss) attributable to IAC shareholders	$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 102,051	$ 43,162	$ (194,775)	$ 8,282	304,924	(41,280)	119,472
Comprehensive income attributable to IAC shareholders									367,370	(76,431)	55,069
Eliminations
Condensed Statements of Operations
Revenue									(617)	(605)	(594)
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									(505)	(412)	(559)
Selling and marketing expense									(519)	(323)	(68)
General and administrative expense									407	130	33
Product development expense									0	0	0
Depreciation									0	0	0
Amortization of intangibles									0	0	0
Goodwill impairment										0	0
Total operating costs and expenses									(617)	(605)	(594)
Operating income (loss)									0	0	0
Equity in earnings of unconsolidated affiliates									(446,430)	(56,319)	(232,433)
Interest expense									0	0	0
Other (expense) income, net									0	0	0
Earnings (loss) before income taxes									(446,430)	(56,319)	(232,433)
Income tax benefit (provision)									0	0	0
(Loss) earnings from continuing operations										(56,319)	(232,433)
Net earnings (loss)									(446,430)
Net (earnings) loss attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									(446,430)	(56,319)	(232,433)
Comprehensive income attributable to IAC shareholders									(512,187)	(2,545)	(163,128)
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)									160	859	720
Selling and marketing expense									1,250	2,353	3,210
General and administrative expense									100,237	89,583	93,090
Product development expense									2,421	4,807	4,311
Depreciation									1,564	1,610	1,918
Amortization of intangibles									0	0	0
Goodwill impairment										0	0
Total operating costs and expenses									105,632	99,212	103,249
Operating income (loss)									(105,632)	(99,212)	(103,249)
Equity in earnings of unconsolidated affiliates									425,675	49,545	215,080
Interest expense									(20,339)	(26,876)	(49,405)
Other (expense) income, net									(39,207)	(1,879)	(3,172)
Earnings (loss) before income taxes									260,497	(78,422)	59,254
Income tax benefit (provision)									44,427	37,142	60,218
(Loss) earnings from continuing operations										(41,280)	119,472
Net earnings (loss)									304,924
Net (earnings) loss attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									304,924	(41,280)	119,472
Comprehensive income attributable to IAC shareholders									367,370	(76,431)	55,069
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statements of Operations
Revenue									753,858	960,000	1,355,222
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									159,488	297,712	341,351
Selling and marketing expense									353,186	417,051	624,979
General and administrative expense									62,340	83,636	94,896
Product development expense									55,232	69,778	73,500
Depreciation									20,668	26,514	23,912
Amortization of intangibles									11,213	41,157	102,622
Goodwill impairment										253,245	14,056
Total operating costs and expenses									662,127	1,189,093	1,275,316
Operating income (loss)									91,731	(229,093)	79,906
Equity in earnings of unconsolidated affiliates									20,755	6,774	17,353
Interest expense									0	0	(6,130)
Other (expense) income, net									28,434	10,209	27,810
Earnings (loss) before income taxes									140,920	(212,110)	118,939
Income tax benefit (provision)									(119,957)	77,851	(42,072)
(Loss) earnings from continuing operations										(134,259)	76,867
Net earnings (loss)									20,963
Net (earnings) loss attributable to noncontrolling interests									0	0	0
Net earnings (loss) attributable to IAC shareholders									20,963	(134,259)	76,867
Comprehensive income attributable to IAC shareholders									7,629	(142,494)	73,970
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statements of Operations
Revenue									2,553,998	2,180,487	1,876,305
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)									491,865	457,571	436,649
Selling and marketing expense									1,027,304	828,016	720,172
General and administrative expense									556,273	357,097	324,036
Product development expense									193,226	138,180	118,812
Depreciation									52,033	43,552	36,375
Amortization of intangibles									30,930	38,269	37,330
Goodwill impairment										22,122	0
Total operating costs and expenses									2,351,631	1,884,807	1,673,374
Operating income (loss)									202,367	295,680	202,931
Equity in earnings of unconsolidated affiliates									0	0	0
Interest expense									(84,956)	(82,234)	(18,101)
Other (expense) income, net									(5,440)	52,320	12,300
Earnings (loss) before income taxes									111,971	265,766	197,130
Income tax benefit (provision)									366,580	(50,059)	(47,662)
(Loss) earnings from continuing operations										215,707	149,468
Net earnings (loss)									478,551
Net (earnings) loss attributable to noncontrolling interests									(53,084)	(25,129)	6,098
Net earnings (loss) attributable to IAC shareholders									425,467	190,578	155,566
Comprehensive income attributable to IAC shareholders									$ 504,558	$ 145,039	$ 89,158

GUARANTOR AND NON-GUARANTOR 112

GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - CONDENSED STATEMENT OF CASH FLOWS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities	$ 416,690	$ 344,141	$ 405,671
Cash flows from investing activities:
Acquisitions, net of cash acquired	(149,094)	(18,403)	(617,402)
Capital expenditures	(75,523)	(78,039)	(62,049)
Investments in time deposits	0	(87,500)	0
Proceeds from maturities of time deposits	0	87,500	0
Proceeds from maturities of time deposits	114,350	252,369	218,462
Purchases of marketable debt securities	(29,891)	(313,943)	(93,134)
Purchases of investments	(9,106)	(12,565)	(34,470)
Net proceeds from the sale of businesses and investments	185,778	172,228	9,413
Intercompany		0
Other, net	2,994	11,215	(3,541)
Net cash provided by (used in) investing activities	39,508	12,862	(582,721)
Cash flows from financing activities:
Proceeds from issuance of IAC debt	517,500	0	0
Principal payments on IAC debt	(393,464)	(126,409)	(80,000)
Proceeds from issuance of Match Group debt	525,000	400,000	788,000
Principal payments on Match Group debt	(445,172)	(450,000)	0
Borrowing under ANGI Homeservices Term Loan	275,000	0	0
Purchase of exchangeable note hedge	(74,365)	0	0
Proceeds from issuance of warrants	23,650	0	0
Debt issuance costs	(33,744)	(7,811)	(19,050)
Fees and expenses related to note exchange			(6,954)
Proceeds from Match Group initial public offering, net of fees and expenses	0	0	428,789
Purchase of IAC treasury stock	(56,424)	(308,948)	(200,000)
Dividends	0		(113,196)
Withholding taxes paid on behalf of employees on net settled stock-based awards			(65,743)
Purchase of Match Group stock-based awards	(272,459)	0	(23,431)
Purchase of noncontrolling interests	(15,439)	(2,740)	(32,207)
Acquisition-related contingent consideration payments	(27,289)	(2,180)	(5,750)
Funds returned from escrow for MyHammer tender offer	10,604	(10,548)	0
Proceeds from (Repayments of) Restricted Cash, Financing Activities	20,141	(141)	(20,000)
Intercompany	0	0	0
Increase in restricted cash related to bond redemptions		(141)	(20,000)
Other, net	(5,000)	(2,705)	607
Net cash (used in) provided by financing activities	(166,124)	(502,829)	678,390
Total cash provided (used)	290,074	(145,826)	501,340
Effect of exchange rate changes on cash and cash equivalents	11,548	(6,434)	(10,298)
Net increase (decrease) in cash and cash equivalents	301,622	(152,260)	491,042
Cash and cash equivalents at beginning of period	1,329,187	1,481,447	990,405
Cash and cash equivalents at end of period	1,630,809	1,329,187	1,481,447
Eliminations
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		0
Cash flows from investing activities:
Acquisitions, net of cash acquired		0
Capital expenditures		0
Investments in time deposits		0
Proceeds from maturities of time deposits		0
Proceeds from maturities of time deposits		0
Purchases of marketable debt securities		0
Purchases of investments		0
Net proceeds from the sale of businesses and investments		0
Intercompany		155,104
Other, net		0
Net cash provided by (used in) investing activities		155,104
Cash flows from financing activities:
Principal payments on IAC debt		0
Proceeds from issuance of Match Group debt		0
Principal payments on Match Group debt		0
Debt issuance costs		0
Purchase of noncontrolling interests		0
Acquisition-related contingent consideration payments		0
Funds returned from escrow for MyHammer tender offer		0
Intercompany		(155,104)
Increase in restricted cash related to bond redemptions		0
Other, net		0
Net cash (used in) provided by financing activities		(155,104)
Total cash provided (used)		0
Effect of exchange rate changes on cash and cash equivalents		0
Net increase (decrease) in cash and cash equivalents		0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0	0
IAC
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities	(61,002)
Cash flows from investing activities:
Acquisitions, net of cash acquired	0
Capital expenditures	(337)
Proceeds from maturities of time deposits	114,350
Purchases of marketable debt securities	(29,891)
Purchases of investments	0
Net proceeds from the sale of businesses and investments	1,266
Other, net	0
Net cash provided by (used in) investing activities	85,388
Cash flows from financing activities:
Proceeds from issuance of IAC debt	0
Principal payments on IAC debt	(393,464)
Proceeds from issuance of Match Group debt	0
Principal payments on Match Group debt	0
Borrowing under ANGI Homeservices Term Loan	0
Purchase of exchangeable note hedge	0
Proceeds from issuance of warrants	23,650
Debt issuance costs	0
Purchase of IAC treasury stock	(56,424)
Purchase of Match Group stock-based awards	0
Purchase of noncontrolling interests	0
Acquisition-related contingent consideration payments	0
Funds returned from escrow for MyHammer tender offer	0
Proceeds from (Repayments of) Restricted Cash, Financing Activities	20,141
Intercompany	424,816
Other, net	251
Net cash (used in) provided by financing activities	7,535
Total cash provided (used)	31,921
Effect of exchange rate changes on cash and cash equivalents	75
Net increase (decrease) in cash and cash equivalents	31,996
Cash and cash equivalents at beginning of period	553,643
Cash and cash equivalents at end of period	585,639	553,643
IAC | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		(62,686)	(121,331)
Cash flows from investing activities:
Acquisitions, net of cash acquired		0	0
Capital expenditures		(479)	(1,332)
Investments in time deposits		0
Proceeds from maturities of time deposits		0
Proceeds from maturities of time deposits		252,369	218,462
Purchases of marketable debt securities		(313,943)	(93,134)
Purchases of investments		0	(6,978)
Net proceeds from the sale of businesses and investments		73,843	1,277
Intercompany		(155,104)
Other, net		126	3,613
Net cash provided by (used in) investing activities		(143,188)	121,908
Cash flows from financing activities:
Principal payments on IAC debt		(126,409)	0
Proceeds from issuance of Match Group debt		0	0
Principal payments on Match Group debt		0
Debt issuance costs		0	(1,876)
Fees and expenses related to note exchange			0
Proceeds from Match Group initial public offering, net of fees and expenses			0
Purchase of IAC treasury stock		(308,948)	(200,000)
Dividends			(113,196)
Withholding taxes paid on behalf of employees on net settled stock-based awards			(65,743)
Purchase of Match Group stock-based awards			0
Purchase of noncontrolling interests		(1,400)	0
Acquisition-related contingent consideration payments		0	0
Funds returned from escrow for MyHammer tender offer		0
Intercompany		122,965	684,716
Increase in restricted cash related to bond redemptions		(141)	(20,000)
Other, net		(313)	166
Net cash (used in) provided by financing activities		(315,141)	311,392
Total cash provided (used)		(521,015)	311,969
Effect of exchange rate changes on cash and cash equivalents		0	0
Net increase (decrease) in cash and cash equivalents		(521,015)	311,969
Cash and cash equivalents at beginning of period	553,643	1,074,658	762,689
Cash and cash equivalents at end of period	585,639	553,643	1,074,658
Guarantor Subsidiaries
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities	131,581
Cash flows from investing activities:
Acquisitions, net of cash acquired	(2,550)
Capital expenditures	(1,050)
Proceeds from maturities of time deposits	0
Purchases of marketable debt securities	0
Purchases of investments	0
Net proceeds from the sale of businesses and investments	0
Other, net	1,944
Net cash provided by (used in) investing activities	(1,656)
Cash flows from financing activities:
Proceeds from issuance of IAC debt	0
Principal payments on IAC debt	0
Proceeds from issuance of Match Group debt	0
Principal payments on Match Group debt	0
Borrowing under ANGI Homeservices Term Loan	0
Purchase of exchangeable note hedge	0
Proceeds from issuance of warrants	0
Debt issuance costs	0
Purchase of IAC treasury stock	0
Purchase of Match Group stock-based awards	0
Purchase of noncontrolling interests	0
Acquisition-related contingent consideration payments	0
Funds returned from escrow for MyHammer tender offer	0
Proceeds from (Repayments of) Restricted Cash, Financing Activities	0
Intercompany	(129,925)
Other, net	0
Net cash (used in) provided by financing activities	(129,925)
Total cash provided (used)	0
Effect of exchange rate changes on cash and cash equivalents	0
Net increase (decrease) in cash and cash equivalents	0
Cash and cash equivalents at beginning of period	0
Cash and cash equivalents at end of period	0	0
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		128,473	242,554
Cash flows from investing activities:
Acquisitions, net of cash acquired		0	(6,078)
Capital expenditures		(5,762)	(13,198)
Investments in time deposits		0
Proceeds from maturities of time deposits		0
Proceeds from maturities of time deposits		0	0
Purchases of marketable debt securities		0	0
Purchases of investments		0	0
Net proceeds from the sale of businesses and investments		1,779	0
Intercompany		0
Other, net		910	385
Net cash provided by (used in) investing activities		(3,073)	(18,891)
Cash flows from financing activities:
Principal payments on IAC debt		0	(80,000)
Proceeds from issuance of Match Group debt		0	0
Principal payments on Match Group debt		0
Debt issuance costs		0	0
Fees and expenses related to note exchange			0
Proceeds from Match Group initial public offering, net of fees and expenses			0
Dividends			0
Withholding taxes paid on behalf of employees on net settled stock-based awards			0
Purchase of Match Group stock-based awards			0
Purchase of noncontrolling interests		0	0
Acquisition-related contingent consideration payments		(351)	(240)
Funds returned from escrow for MyHammer tender offer		0
Intercompany		(122,965)	(143,423)
Increase in restricted cash related to bond redemptions			0
Other, net		(2,084)
Net cash (used in) provided by financing activities		(125,400)	(223,663)
Effect of exchange rate changes on cash and cash equivalents		0	0
Net increase (decrease) in cash and cash equivalents		0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Non-Guarantor Subsidiaries
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities	346,111
Cash flows from investing activities:
Acquisitions, net of cash acquired	(146,544)
Capital expenditures	(74,136)
Proceeds from maturities of time deposits	0
Purchases of marketable debt securities	0
Purchases of investments	(9,106)
Net proceeds from the sale of businesses and investments	184,512
Other, net	1,050
Net cash provided by (used in) investing activities	(44,224)
Cash flows from financing activities:
Proceeds from issuance of IAC debt	517,500
Principal payments on IAC debt	0
Proceeds from issuance of Match Group debt	525,000
Principal payments on Match Group debt	(445,172)
Borrowing under ANGI Homeservices Term Loan	275,000
Purchase of exchangeable note hedge	(74,365)
Proceeds from issuance of warrants	0
Debt issuance costs	(33,744)
Purchase of IAC treasury stock	0
Purchase of Match Group stock-based awards	(272,459)
Purchase of noncontrolling interests	(15,439)
Acquisition-related contingent consideration payments	(27,289)
Funds returned from escrow for MyHammer tender offer	10,604
Proceeds from (Repayments of) Restricted Cash, Financing Activities	0
Intercompany	(294,891)
Other, net	(5,251)
Net cash (used in) provided by financing activities	(43,734)
Total cash provided (used)	258,153
Effect of exchange rate changes on cash and cash equivalents	11,473
Net increase (decrease) in cash and cash equivalents	269,626
Cash and cash equivalents at beginning of period	775,544
Cash and cash equivalents at end of period	1,045,170	775,544
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Cash Flows
Net cash (used in) provided by operating activities		278,354	284,448
Cash flows from investing activities:
Acquisitions, net of cash acquired		(18,403)	(611,324)
Capital expenditures		(71,798)	(47,519)
Investments in time deposits		(87,500)
Proceeds from maturities of time deposits		87,500
Proceeds from maturities of time deposits		0	0
Purchases of marketable debt securities		0	0
Purchases of investments		(12,565)	(27,492)
Net proceeds from the sale of businesses and investments		96,606	8,136
Intercompany		0
Other, net		10,179	(7,539)
Net cash provided by (used in) investing activities		4,019	(685,738)
Cash flows from financing activities:
Principal payments on IAC debt		0	0
Proceeds from issuance of Match Group debt		400,000	788,000
Principal payments on Match Group debt		(450,000)
Debt issuance costs		(7,811)	(17,174)
Fees and expenses related to note exchange			(6,954)
Proceeds from Match Group initial public offering, net of fees and expenses			428,789
Dividends			0
Withholding taxes paid on behalf of employees on net settled stock-based awards			0
Purchase of Match Group stock-based awards			(23,431)
Purchase of noncontrolling interests		(1,340)	(32,207)
Acquisition-related contingent consideration payments		(1,829)	(5,510)
Funds returned from escrow for MyHammer tender offer		(10,548)
Intercompany		155,104	(541,293)
Increase in restricted cash related to bond redemptions			0
Other, net		(308)	441
Net cash (used in) provided by financing activities		92,816	590,661
Total cash provided (used)		375,189	189,371
Effect of exchange rate changes on cash and cash equivalents		(6,434)	(10,298)
Net increase (decrease) in cash and cash equivalents		368,755	179,073
Cash and cash equivalents at beginning of period	775,544	406,789	227,716
Cash and cash equivalents at end of period	1,045,170	775,544	406,789
IAC/InterActiveCorp
Cash flows from financing activities:
Proceeds from the exercise of stock options	82,397	25,821	27,325
Withholding taxes paid on behalf of employees on net settled stock-based awards	(93,832)	(26,716)
IAC/InterActiveCorp | 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
IAC/InterActiveCorp | IAC
Cash flows from financing activities:
Proceeds from the exercise of stock options	82,397	25,821	27,325
Withholding taxes paid on behalf of employees on net settled stock-based awards	(93,832)	(26,716)	(65,743)
IAC/InterActiveCorp | IAC | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from the exercise of stock options		25,821	27,325
Withholding taxes paid on behalf of employees on net settled stock-based awards		(26,716)
IAC/InterActiveCorp | Guarantor Subsidiaries
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
IAC/InterActiveCorp | 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
IAC/InterActiveCorp | Non-Guarantor Subsidiaries
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
IAC/InterActiveCorp | Non-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
Match Group
Cash flows from financing activities:
Proceeds from the exercise of stock options	59,442	39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards	(254,210)	(29,830)
Match Group | 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 | IAC
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 | IAC | Reportable Legal Entities
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 | Guarantor Subsidiaries
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 | Guarantor Subsidiaries | Reportable Legal Entities
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 | Non-Guarantor Subsidiaries
Cash flows from financing activities:
Proceeds from the exercise of stock options	59,442	39,378	0
Withholding taxes paid on behalf of employees on net settled stock-based awards	(254,210)	(29,830)	0
Match Group | Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from financing activities:
Proceeds from the exercise of stock options		39,378
Withholding taxes paid on behalf of employees on net settled stock-based awards		(29,830)
ANGI Homeservices
Cash flows from financing activities:
Proceeds from the exercise of stock options	1,653
Withholding taxes paid on behalf of employees on net settled stock-based awards	(10,113)
ANGI Homeservices | IAC
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
ANGI Homeservices | Guarantor Subsidiaries
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
ANGI Homeservices | Non-Guarantor Subsidiaries
Cash flows from financing activities:
Proceeds from the exercise of stock options	1,653	0	0
Withholding taxes paid on behalf of employees on net settled stock-based awards	$ (10,113)	$ 0	$ 0

QUARTERLY RESULTS (UNAUDITED) -

QUARTERLY RESULTS (UNAUDITED) - SUMMARY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Revenue	$ 950,585	$ 828,434	$ 767,387	$ 760,833	$ 811,162	$ 764,102	$ 745,439	$ 819,179	$ 3,307,239	$ 3,139,882	$ 3,230,933
Cost of revenue	199,727	166,290	139,033	145,958	212,468	179,131	170,397	193,734	651,008	755,730	778,161
Operating income (loss)	94,360	(18,589)	75,635	37,060	112,820	85,584	(252,446)	21,417	188,466	(32,625)	179,588
Net earnings	23,349	225,639	80,557	28,463	114,117	52,340	(190,542)	7,934	358,008	(16,151)	113,374
Net earnings attributable to IAC shareholders	$ 32,804	$ 179,643	$ 66,268	$ 26,209	$ 102,051	$ 43,162	$ (194,775)	$ 8,282	$ 304,924	$ (41,280)	$ 119,472
Per share information attributable to IAC shareholders:
Basic (loss) earnings per share (USD per share)	$ 0.40	$ 2.22	$ 0.84	$ 0.34	$ 1.29	$ 0.54	$ (2.45)	$ 0.10	$ 3.81	$ (0.52)	$ 1.44
Diluted (loss) earnings per share (USD per share)	$ 0.37	$ 1.79	$ 0.70	$ 0.29	$ 1.18	$ 0.49	$ (2.45)	$ 0.09	$ 3.18	$ (0.52)	$ 1.33
Stock-based compensation expense									$ 264,618	$ 104,820	$ 105,450
Income tax expense (benefit)		$ 257,000							(291,050)	$ (64,934)	$ 29,516
Impairment loss on goodwill							$ 183,500
Impairment of intangible assets							$ 7,200
HomeAdvisor
Per share information attributable to IAC shareholders:
Stock-based compensation expense	$ 15,800	60,900
Angie's List
Per share information attributable to IAC shareholders:
After-tax costs	13,900	$ 17,400							$ 13,900
Write-off due to deferred revenue	$ 7,600
PriceRunner | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Per share information attributable to IAC shareholders:
Gain on sale of business								$ 11,900
ShoeBuy | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Per share information attributable to IAC shareholders:
Gain on sale of business					$ 37,500

SCHEDULE II - VALUATION AND 114

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts and revenue reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	$ 16,405	$ 16,528	$ 12,437
Charges to Earnings	28,930	17,733	16,648
Charges to Other Accounts	(1,006)	(695)	(536)
Deductions	(32,840)	(17,161)	(12,021)
Balance at end of period	11,489	16,405	16,528
Sales returns accrual
Movement in Valuation Allowances and Reserves
Balance at beginning of period	80	828	1,119
Charges to Earnings	0	14,998	17,569
Charges to Other Accounts	(80)	(962)	0
Deductions	0	(14,784)	(17,860)
Balance at end of period	0	80	828
Deferred tax valuation allowance
Movement in Valuation Allowances and Reserves
Balance at beginning of period	88,170	90,482	98,350
Charges to Earnings	38,144	(837)	(6,072)
Charges to Other Accounts	6,284	(1,475)	(1,796)
Deductions	0	0	0
Balance at end of period	132,598	88,170	90,482
Other reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	2,822	2,801	2,204
Balance at end of period	$ 2,544	$ 2,822	$ 2,801