Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value Measurements [Abstract]

Assets And Liabilities Measured At Fair Value On Recurring Basis

			Quoted Prices in		Significant Other		Significant
	Fair Value		Active Markets for		Observable		Unobservable
	September 30,		Identical Assets		Inputs		Inputs
	2011		(Level 1)		(Level 2)		(Level 3)
Recurring:
Investments in money market and short term treasury instruments	$	178,413	$	178,413	$	—	$	—
Retained interest in entities		10,598		—		—		10,598
Total, net	$	189,011	$	178,413	$	—	$	10,598

     Fair value as of December 31, 2010

			Quoted Prices in		Significant Other		Significant
	Fair Value		Active Markets for		Observable		Unobservable
	December 31,		Identical Assets		Inputs		Inputs
	2010		(Level 1)		(Level 2)		(Level 3)
Recurring:
Investments in money market	$	177,816	$	177,816	$	—	$	—
Retained interest in entities		10,283		—		—		10,283
Total, net	$	188,099	$	177,816	$	—	$	10,283

Reconciliation Of Retained Interest

	2011
Balance January 1	$	10,283
Additions		—
Accretion of interest income		315
Balance September 30	$	10,598

Assets Measured At Fair Value On Nonrecurring Basis

	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable		Fair Value		Total
	Identical Assets		Inputs		Inputs		September 30,		Impairment
	(Level 1)		(Level 2)		(Level 3)		2011		Losses
Non-financial assets:
Investment in real estate	$	—	$	1,224	$	1,701	$	2,925	$	2,479