GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details3) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	$ 85,779	$ 148,771
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(43,286)	(103,380)
Capital expenditures	(26,816)	(26,557)
Proceeds from maturities and sales of marketable debt securities	14,613	998
Purchases of marketable debt securities	(93,134)	(78,380)
Purchases of long-term investments	(12,840)	(14,701)
Other, net	8,599	2,187
Net cash used in investing activities attributable to continuing operations	(152,864)	(219,833)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(200,000)	0
Dividends	(56,729)	(40,086)
Issuance of common stock, net of withholding taxes	(20,656)	(13,823)
Excess tax benefits from stock-based awards	36,465	32,889
Purchase of noncontrolling interests	(15,338)	(30,000)
Funds returned from escrow for Meetic tender offer	0	12,354
Acquisition-related contingent consideration payments	(5,705)	(7,630)
Other, net	430	(141)
Net cash used in financing activities attributable to continuing operations	(261,533)	(46,437)
Total cash used in continuing operations	(328,618)	(117,499)
Total cash used in discontinued operations	(243)	(157)
Effect of exchange rate changes on cash and cash equivalents	(5,135)	4,538
Net decrease in cash and cash equivalents	(333,996)	(113,118)
Cash and cash equivalents at beginning of period	990,405	1,100,444
Cash and cash equivalents at end of period	656,409	987,326
IAC Consolidated
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	85,779	148,771
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(43,286)	(103,380)
Capital expenditures	(26,816)	(26,557)
Proceeds from maturities and sales of marketable debt securities	14,613	998
Purchases of marketable debt securities	(93,134)	(78,380)
Purchases of long-term investments	(12,840)	(14,701)
Other, net	8,599	2,187
Net cash used in investing activities attributable to continuing operations	(152,864)	(219,833)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(200,000)
Dividends	(56,729)	(40,086)
Issuance of common stock, net of withholding taxes	(20,656)	(13,823)
Excess tax benefits from stock-based awards	36,465	32,889
Purchase of noncontrolling interests	(15,338)	(30,000)
Funds returned from escrow for Meetic tender offer		12,354
Acquisition-related contingent consideration payments	(5,705)	(7,630)
Intercompany	0	0
Other, net	430	(141)
Net cash used in financing activities attributable to continuing operations	(261,533)	(46,437)
Total cash used in continuing operations	(328,618)	(117,499)
Total cash used in discontinued operations	(243)	(157)
Effect of exchange rate changes on cash and cash equivalents	(5,135)	4,538
Net decrease in cash and cash equivalents	(333,996)	(113,118)
Cash and cash equivalents at beginning of period	990,405	1,100,444
Cash and cash equivalents at end of period	656,409	987,326
IAC
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	(124,420)	(38,576)
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	0	0
Capital expenditures	(988)	(2,390)
Proceeds from maturities and sales of marketable debt securities	14,613	998
Purchases of marketable debt securities	(93,134)	(78,380)
Purchases of long-term investments	0	(3,000)
Other, net	3,613	0
Net cash used in investing activities attributable to continuing operations	(75,896)	(82,772)
Cash flows from financing activities attributable to continuing operations:
Purchase of treasury stock	(200,000)
Dividends	(56,729)	(40,086)
Issuance of common stock, net of withholding taxes	(20,656)	(13,823)
Excess tax benefits from stock-based awards	36,334	22,116
Purchase of noncontrolling interests	0	0
Acquisition-related contingent consideration payments	0	0
Intercompany	107,102	104,410
Other, net	166	(383)
Net cash used in financing activities attributable to continuing operations	(133,783)	72,234
Total cash used in continuing operations	(334,099)	(49,114)
Total cash used in discontinued operations	(246)	(116)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net decrease in cash and cash equivalents	(334,345)	(49,230)
Cash and cash equivalents at beginning of period	766,076	782,022
Cash and cash equivalents at end of period	431,731	732,792
Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	232,853	193,388
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(3,675)	(88,205)
Capital expenditures	(18,242)	(16,477)
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities	0	0
Purchases of long-term investments	0	(6,761)
Other, net	(1,086)	11
Net cash used in investing activities attributable to continuing operations	(23,003)	(111,432)
Cash flows from financing activities attributable to continuing operations:
Purchase of noncontrolling interests	0	(30,000)
Acquisition-related contingent consideration payments	(195)	(257)
Intercompany	(206,557)	(51,723)
Net cash used in financing activities attributable to continuing operations	(206,752)	(81,980)
Total cash used in continuing operations	3,098	(24)
Total cash used in discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	2	24
Net decrease in cash and cash equivalents	3,100	0
Cash and cash equivalents at beginning of period	1,021	0
Cash and cash equivalents at end of period	4,121	0
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities attributable to continuing operations	(22,654)	(6,041)
Cash flows from investing activities attributable to continuing operations:
Acquisitions, net of cash acquired	(39,611)	(15,175)
Capital expenditures	(7,586)	(7,690)
Proceeds from maturities and sales of marketable debt securities	0	0
Purchases of marketable debt securities	0	0
Purchases of long-term investments	(12,840)	(4,940)
Other, net	6,072	2,176
Net cash used in investing activities attributable to continuing operations	(53,965)	(25,629)
Cash flows from financing activities attributable to continuing operations:
Excess tax benefits from stock-based awards	131	10,773
Purchase of noncontrolling interests	(15,338)	0
Funds returned from escrow for Meetic tender offer		12,354
Acquisition-related contingent consideration payments	(5,510)	(7,373)
Intercompany	99,455	(52,687)
Other, net	264	242
Net cash used in financing activities attributable to continuing operations	79,002	(36,691)
Total cash used in continuing operations	2,383	(68,361)
Total cash used in discontinued operations	3	(41)
Effect of exchange rate changes on cash and cash equivalents	(5,137)	4,514
Net decrease in cash and cash equivalents	(2,751)	(63,888)
Cash and cash equivalents at beginning of period	223,308	318,422
Cash and cash equivalents at end of period	$ 220,557	$ 254,534