CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interests	Comprehensive Income (Loss)	Common stock	Class B convertible common stock Common Stock
Balance at Dec. 31, 2008	$ 4,046,671	$ 10,731,149	$ 227,445	$ 2,180	$ (6,914,329)			$ 210	$ 16
Balance (in shares) at Dec. 31, 2008								210,217	16,157
Comprehensive income (loss):
Net earnings (loss) attributable to IAC shareholders for the year	(978,822)		(978,822)
Net (income) attributable to noncontrolling interests	1,090
Net earnings (loss) for the year	(978,822)						(978,822)
Change in foreign currency translation adjustment, net of tax (benefit) provision of $(4,711) and $2,186 for the year ended December 2010 and 2009 respectively	14,918			14,918			14,918
Change in net unrealized gains (losses) on available-for-sale securities, net of tax provision (benefit) of $5,460, $(1,555) and $1,440 for the year ended December 2011, 2010 and 2009 respectively	7,405			7,405			7,405
Comprehensive income (loss)	(956,499)						(956,499)
Non-cash compensation expense	69,629	69,629
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	7,431	7,430						1
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes (in shares)								834
Income tax benefit (provision) related to the exercise of stock options, vesting of restricted stock units and other	(11,737)	(11,737)
Issuance of common stock upon the exercise of warrants	152,694	152,682						12
Issuance of common stock upon the exercise of warrants (in shares)								11,607
Purchase of treasury stock	(554,203)				(554,203)
Fair value of redeemable noncontrolling interests adjustment	(1,033)	(1,033)
Settlement of vested stock-based awards denominated in subsidiaries' equity, net of tax	(10,044)	(10,044)
Spin-off of HSNi, ILG, Ticketmaster and Tree.com to shareholders	4,052	4,052
Balance at Dec. 31, 2009	2,746,961	10,942,128	(751,377)	24,503	(7,468,532)			223	16
Balance (in shares) at Dec. 31, 2009								222,658	16,157
Comprehensive income (loss):
Net earnings (loss) attributable to IAC shareholders for the year	99,359		99,359
Net (income) attributable to noncontrolling interests	5,007
Net earnings (loss) for the year	99,359						99,359
Change in foreign currency translation adjustment, net of tax (benefit) provision of $(4,711) and $2,186 for the year ended December 2010 and 2009 respectively	(4,237)			(4,237)			(4,237)
Change in net unrealized gains (losses) on available-for-sale securities, net of tax provision (benefit) of $5,460, $(1,555) and $1,440 for the year ended December 2011, 2010 and 2009 respectively	(2,720)			(2,720)			(2,720)
Comprehensive income (loss)	92,402						92,402
Non-cash compensation expense	85,048	85,048
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	30,933	30,930						3
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes (in shares)								2,864
Income tax benefit (provision) related to the exercise of stock options, vesting of restricted stock units and other	(12,237)	(12,237)
Purchase of treasury stock	(530,885)				(530,885)
Receipt of stock from Liberty Media Corporation	(364,169)				(364,169)
Fair value of redeemable noncontrolling interests adjustment	2,059	2,059
Settlement of vested stock-based awards denominated in subsidiaries' equity, net of tax	(44)	(44)
Settlement of vested stock-based awards denominated in subsidiaries' equity, net of tax (in shares)								352
Balance at Dec. 31, 2010	2,050,068	11,047,884	(652,018)	17,546	(8,363,586)			226	16
Balance (in shares) at Dec. 31, 2010								225,874	16,157
Comprehensive income (loss):
Net earnings (loss) attributable to IAC shareholders for the year	174,233		174,233
Net (income) attributable to noncontrolling interests	2,656					(2,417)
Net earnings (loss) for the year	171,816						171,816
Change in foreign currency translation adjustment, net of tax (benefit) provision of $(4,711) and $2,186 for the year ended December 2010 and 2009 respectively	(46,470)			(41,201)		(5,269)	(46,470)
Change in net unrealized gains (losses) on available-for-sale securities, net of tax provision (benefit) of $5,460, $(1,555) and $1,440 for the year ended December 2011, 2010 and 2009 respectively	11,212			11,212			11,212
Comprehensive income (loss)	136,558					(7,686)	136,558
Noncontrolling interests related to acquisition of Meetic S.A.	64,831					64,831
Non-cash compensation expense	87,774	86,725				1,049
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	56,736	56,731						5
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes (in shares)								5,010
Income tax benefit (provision) related to the exercise of stock options, vesting of restricted stock units and other	28,363	28,363
Issuance of common stock upon the exercise of warrants	76,042	76,039						3
Issuance of common stock upon the exercise of warrants (in shares)								3,217
Cash dividend declared on common stock	(14,399)	(11,296)				(3,103)
Purchase of treasury stock	(518,637)				(518,637)
Receipt of stock from Liberty Media Corporation	(2,923)				(2,923)
Fair value of redeemable noncontrolling interests adjustment	(4,273)	(4,273)
Balance at Dec. 31, 2011	$ 1,960,140	$ 11,280,173	$ (477,785)	$ (12,443)	$ (8,885,146)	$ 55,091		$ 234	$ 16
Balance (in shares) at Dec. 31, 2011								234,101	16,157