GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details3) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	$ 228,263	$ 205,527
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(36,913)	(20,411)
Capital expenditures	(47,819)	(20,353)
Proceeds from maturities and sales of marketable debt securities	12,502	39,000
Purchases of marketable debt securities	0	(24,254)
Proceeds from sales of long-term investments	310	12,527
Purchases of long-term investments	(25,259)	(6,244)
Other, net	(1,443)	(12,603)
Net cash used in investing activities attributable to continuing operations	(98,622)	(32,338)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(162,660)	(359,231)
Net (payments) proceeds from stock-based award activities	(868)	301,677
Dividends	(38,880)	(21,697)
Excess tax benefits from stock-based awards	23,547	14,353
Principal payments on long-term debt	(15,844)	0
Other, net	(3,634)	(2,842)
Net cash used in financing activities attributable to continuing operations	(198,339)	(67,740)
Total cash (used in) provided by continuing operations	(68,698)	105,449
Total cash provided by (used in) discontinued operations	2,335	(729)
Effect of exchange rate changes on cash and cash equivalents	(4,889)	(1,677)
Net (decrease) increase in cash and cash equivalents	(71,252)	103,043
Cash and cash equivalents at beginning of period	749,977	704,153
Cash and cash equivalents at end of period	678,725	807,196
IAC Consolidated
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	228,263	205,527
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(36,913)	(20,411)
Capital expenditures	(47,819)	(20,353)
Proceeds from maturities and sales of marketable debt securities	12,502	39,000
Purchases of marketable debt securities		(24,254)
Proceeds from sales of long-term investments	310	12,527
Purchases of long-term investments	(25,259)	(6,244)
Other, net	(1,443)	(12,603)
Net cash used in investing activities attributable to continuing operations	(98,622)	(32,338)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(162,660)	(359,231)
Net (payments) proceeds from stock-based award activities	(868)	301,677
Dividends	(38,880)	(21,697)
Excess tax benefits from stock-based awards	23,547	14,353
Principal payments on long-term debt	(15,844)
Intercompany	0	0
Other, net	(3,634)	(2,842)
Net cash used in financing activities attributable to continuing operations	(198,339)	(67,740)
Total cash (used in) provided by continuing operations	(68,698)	105,449
Total cash provided by (used in) discontinued operations	2,335	(729)
Effect of exchange rate changes on cash and cash equivalents	(4,889)	(1,677)
Net (decrease) increase in cash and cash equivalents	(71,252)	103,043
Cash and cash equivalents at beginning of period	749,977	704,153
Cash and cash equivalents at end of period	678,725	807,196
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:
Purchase of treasury stock	0	0
Net (payments) proceeds from stock-based award activities	0	0
Dividends	0	0
Excess tax benefits from stock-based awards	0	0
Principal payments on long-term debt	0
Intercompany	0	0
Other, net	0	0
Net cash used in financing activities attributable to continuing operations	0	0
Total cash (used in) provided by continuing operations	0	0
Total cash provided by (used in) discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase 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	7,733	12,603
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(30,841)	(1,285)
Capital expenditures	(8,618)	(7,312)
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities		0
Proceeds from sales of long-term investments	310	0
Purchases of long-term investments	(7,897)	(6,220)
Other, net	(1,426)	(12,033)
Net cash used in investing activities attributable to continuing operations	(48,472)	(26,850)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	0	0
Net (payments) proceeds from stock-based award activities	0	0
Dividends	0	0
Excess tax benefits from stock-based awards	0	0
Principal payments on long-term debt	0
Intercompany	63,490	67,383
Other, net	(1,483)	(2,842)
Net cash used in financing activities attributable to continuing operations	62,007	64,541
Total cash (used in) provided by continuing operations	21,268	50,294
Total cash provided by (used in) discontinued operations	0	(73)
Effect of exchange rate changes on cash and cash equivalents	(4,912)	(1,678)
Net (decrease) increase in cash and cash equivalents	16,356	48,543
Cash and cash equivalents at beginning of period	248,902	158,931
Cash and cash equivalents at end of period	265,258	207,474
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	253,527	204,438
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(6,072)	(19,126)
Capital expenditures	(38,482)	(13,010)
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	(24)
Other, net	38	(220)
Net cash used in investing activities attributable to continuing operations	(44,516)	(32,380)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	0	0
Net (payments) proceeds from stock-based award activities	0	0
Dividends	0	0
Excess tax benefits from stock-based awards	0	4,892
Principal payments on long-term debt	0
Intercompany	(207,810)	(176,951)
Other, net	(1,224)	0
Net cash used in financing activities attributable to continuing operations	(209,034)	(172,059)
Total cash (used in) provided by continuing operations	(23)	(1)
Total cash provided by (used in) discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	23	1
Net (decrease) increase 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
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	(32,997)	(11,514)
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	0	0
Capital expenditures	(719)	(31)
Proceeds from maturities and sales of marketable debt securities	12,502	39,000
Purchases of marketable debt securities		(24,254)
Proceeds from sales of long-term investments	0	12,527
Purchases of long-term investments	(17,362)	0
Other, net	(55)	(350)
Net cash used in investing activities attributable to continuing operations	(5,634)	26,892
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(162,660)	(359,231)
Net (payments) proceeds from stock-based award activities	(868)	301,677
Dividends	(38,880)	(21,697)
Excess tax benefits from stock-based awards	23,547	9,461
Principal payments on long-term debt	(15,844)
Intercompany	144,320	109,568
Other, net	(927)	0
Net cash used in financing activities attributable to continuing operations	(51,312)	39,778
Total cash (used in) provided by continuing operations	(89,943)	55,156
Total cash provided by (used in) discontinued operations	2,335	(656)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	(87,608)	54,500
Cash and cash equivalents at beginning of period	501,075	545,222
Cash and cash equivalents at end of period	$ 413,467	$ 599,722