GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details3) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	$ 294,661	$ 324,330
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(244,482)	(39,457)
Capital expenditures	(39,033)	(64,114)
Proceeds from maturities and sales of marketable debt securities	998	12,502
Purchases of marketable debt securities	(110,886)	0
Proceeds from sales of long-term investments	11,107	42,286
Purchases of long-term investments	(17,703)	(26,605)
Other, net	817	8,904
Net cash used in investing activities attributable to continuing operations	(399,182)	(66,484)
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt	0	(15,844)
Purchase of treasury stock	0	(168,376)
Dividends	(68,505)	(58,882)
Issuance of common stock, net of withholding taxes	(4,823)	6,456
Excess tax benefits from stock-based awards	41,320	26,430
Purchase of noncontrolling interests	(30,328)	(55,561)
Funds returned from escrow for Meetic tender offer	12,354	0
Acquisition-related contingent consideration payment	(7,373)	0
Other, net	(1,397)	(3,386)
Net cash used in financing activities attributable to continuing operations	(58,752)	(269,163)
Net Cash Provided by (Used in) Continuing Operations	(163,273)	(11,317)
Total cash (used in) provided by discontinued operations	(171)	2,257
Effect of exchange rate changes on cash and cash equivalents	(5,288)	735
Net decrease in cash and cash equivalents	(168,732)	(8,325)
Cash and cash equivalents at beginning of period	1,100,444	749,977
Cash and cash equivalents at end of period	931,712	741,652
IAC
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	(50,458)	(55,102)
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	0	0
Capital expenditures	(2,375)	(742)
Proceeds from maturities and sales of marketable debt securities	998	12,502
Purchases of marketable debt securities	(110,886)
Proceeds from sales of long-term investments	0	41,976
Purchases of long-term investments	(3,000)	(17,362)
Other, net	0	0
Net cash used in investing activities attributable to continuing operations	(115,263)	36,374
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt		(15,844)
Purchase of treasury stock		(168,376)
Dividends	(68,505)	(58,882)
Issuance of common stock, net of withholding taxes	(4,823)	6,456
Excess tax benefits from stock-based awards	31,041	26,430
Purchase of noncontrolling interests	0	0
Funds returned from escrow for Meetic tender offer	0
Acquisition-related contingent consideration payment	0
Intercompany Financing Activites	101,656	178,663
Other, net	(382)	(951)
Net cash used in financing activities attributable to continuing operations	58,987	(32,504)
Net Cash Provided by (Used in) Continuing Operations	(106,734)	(51,232)
Total cash (used in) provided by discontinued operations	(136)	2,254
Effect of exchange rate changes on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	(106,870)	(48,978)
Cash and cash equivalents at beginning of period	782,022	501,075
Cash and cash equivalents at end of period	675,152	452,097
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	349,842	401,921
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(191,509)	(6,584)
Capital expenditures	(25,526)	(52,742)
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities	0
Proceeds from sales of long-term investments	0	0
Purchases of long-term investments	(7,043)	0
Other, net	10	(1,717)
Net cash used in investing activities attributable to continuing operations	(224,068)	(61,043)
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt		0
Purchase of treasury stock
Dividends
Issuance of common stock, net of withholding taxes
Excess tax benefits from stock-based awards
Purchase of noncontrolling interests	(30,000)	0
Funds returned from escrow for Meetic tender offer	0
Acquisition-related contingent consideration payment	0
Intercompany Financing Activites	(94,492)	(339,665)
Other, net	(1,310)	(1,225)
Net cash used in financing activities attributable to continuing operations	(125,802)	(340,890)
Net Cash Provided by (Used in) Continuing Operations	(28)	(12)
Total cash (used in) provided by discontinued operations
Effect of exchange rate changes on cash and cash equivalents	28	12
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	(4,723)	(22,489)
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(52,973)	(32,873)
Capital expenditures	(11,132)	(10,630)
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities	0
Proceeds from sales of long-term investments	11,107	310
Purchases of long-term investments	(7,660)	(9,243)
Other, net	807	10,621
Net cash used in investing activities attributable to continuing operations	(59,851)	(41,815)
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt		0
Purchase of treasury stock
Dividends
Issuance of common stock, net of withholding taxes
Excess tax benefits from stock-based awards	10,279
Purchase of noncontrolling interests	(328)	(55,561)
Funds returned from escrow for Meetic tender offer	12,354
Acquisition-related contingent consideration payment	(7,373)
Intercompany Financing Activites	(7,164)	161,002
Other, net	295	(1,210)
Net cash used in financing activities attributable to continuing operations	8,063	104,231
Net Cash Provided by (Used in) Continuing Operations	(56,511)	39,927
Total cash (used in) provided by discontinued operations	(35)	3
Effect of exchange rate changes on cash and cash equivalents	(5,316)	723
Net decrease in cash and cash equivalents	(61,862)	40,653
Cash and cash equivalents at beginning of period	318,422	248,902
Cash and cash equivalents at end of period	256,560	289,555
Total Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	0	0
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	0	0
Capital expenditures	0	0
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities	0
Proceeds from sales of long-term investments	0	0
Purchases of long-term investments	0	0
Other, net	0	0
Net cash used in investing activities attributable to continuing operations	0	0
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt		0
Purchase of treasury stock		0
Dividends	0	0
Issuance of common stock, net of withholding taxes	0	0
Excess tax benefits from stock-based awards	0	0
Purchase of noncontrolling interests	0	0
Funds returned from escrow for Meetic tender offer	0
Acquisition-related contingent consideration payment	0
Intercompany Financing Activites	0	0
Other, net	0	0
Net cash used in financing activities attributable to continuing operations	0	0
Net Cash Provided by (Used in) Continuing Operations	0	0
Total cash (used in) provided by discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
IAC Consolidated
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	294,661	324,330
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(244,482)	(39,457)
Capital expenditures	(39,033)	(64,114)
Proceeds from maturities and sales of marketable debt securities	998	12,502
Purchases of marketable debt securities	(110,886)
Proceeds from sales of long-term investments	11,107	42,286
Purchases of long-term investments	(17,703)	(26,605)
Other, net	817	8,904
Net cash used in investing activities attributable to continuing operations	(399,182)	(66,484)
Cash flows from financing activities attributable to continuing operations:
Principal payments on long-term debt		(15,844)
Purchase of treasury stock		(168,376)
Dividends	(68,505)	(58,882)
Issuance of common stock, net of withholding taxes	(4,823)	6,456
Excess tax benefits from stock-based awards	41,320	26,430
Purchase of noncontrolling interests	(30,328)
Funds returned from escrow for Meetic tender offer	12,354
Acquisition-related contingent consideration payment	(7,373)
Intercompany Financing Activites	0	0
Other, net	(1,397)	(3,386)
Net cash used in financing activities attributable to continuing operations	(58,752)	(269,163)
Net Cash Provided by (Used in) Continuing Operations	(163,273)	(11,317)
Total cash (used in) provided by discontinued operations	(171)	2,257
Effect of exchange rate changes on cash and cash equivalents	(5,288)	735
Net decrease in cash and cash equivalents	(168,732)	(8,325)
Cash and cash equivalents at beginning of period	1,100,444	749,977
Cash and cash equivalents at end of period	$ 931,712	$ 741,652