Consolidated Statements Of Changes In Equity (USD $) In Thousands	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]	Non-controlling Interest [Member]	Total
Balance at Dec. 31, 2009	$ 39	$ (12,031)	$ 3,573,347	$ (3,351,888)	$ 71,198	$ 21,077	$ 301,742
Balance, shares at Dec. 31, 2009	38,796	(2,440)
Equity-based compensation related to stock appreciation rights and stock options			1,043				1,043
Equity-based compensation related to deferred stock units			97				97
Equity-based compensation related to restricted stock			76				76
Issuance of deferred stock units to directors, net of forfeitures			114				114
Issuance of deferred stock units to directors, net of forfeitures, shares	46
Issuance of restricted stock			(6)				(6)
Issuance of restricted stock, shares	24
Exercise of stock appreciation rights, net of surrenders			(62)				(62)
Exercise of stock appreciation rights, net of surrenders, shares	12
Impact of redeemable noncontrolling interest accretion			(126)				(126)
Impact of incremental acquisition of ICG Commerce			(27,639)		18	(7,632)	(35,253)
Impact of subsidiary equity transactions			562			(81)	481
Noncontrolling owners share of Accumulated Other Comprehensive Income of consolidated subsidiary					16	(16)
Net unrealized depreciation in marketable securities and reclassification adjustments					(62,199)		(62,199)
Net income (loss)				44,532		587	45,119
Balance at Jun. 30, 2010	39	(12,031)	3,547,406	(3,307,356)	9,033	13,935	251,026
Balance, shares at Jun. 30, 2010	38,878	(2,440)
Balance at Dec. 31, 2010	39	(12,031)	3,541,044	(3,305,299)	54	4,622	228,429
Balance, shares at Dec. 31, 2010	39,439	(2,440)
Equity-based compensation related to stock appreciation rights and stock options			1,034				1,034
Equity-based compensation related to deferred stock units			353				353
Equity-based compensation related to restricted stock			177				177
Issuance of deferred stock units to directors, net of forfeitures			81				81
Issuance of deferred stock units to directors, net of forfeitures, shares	65
Issuance of restricted stock
Issuance of restricted stock, shares	82
Exercise of stock appreciation rights and stock options, net of surrenders	1		(125)				(124)
Exercise of stock appreciation rights and stock options, net of surrenders, shares	24
Impact of redeemable noncontrolling interest accretion			(199)				(199)
Impact of incremental acquisition of ICG Commerce			(1,059)			(261)	(1,320)
Impact of subsidiary equity transactions			556			665	1,221
Repurchase of common stock		(770)					(770)
Repurchase of common stock, shares		(67)
Noncontrolling owners share of Accumulated Other Comprehensive Income of consolidated subsidiary					(15)	15
Net income (loss)				12,657		712	13,369
Balance at Jun. 30, 2011	$ 40	$ (12,801)	$ 3,541,862	$ (3,292,642)	$ 39	$ 5,753	$ 242,251
Balance, shares at Jun. 30, 2011	39,610	(2,507)