Commitments and Contingencies (Details)			1 Months Ended		3 Months Ended		0 Months Ended
	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	May 31, 2010 Opry Mills Mall Limited Partnership USD ($)	Dec. 31, 2012 Mazeikiu Nafta USD ($)	Mar. 31, 2013 Commitments to fund certain limited partnerships or subsidiaries USD ($)	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Term Credit Agreement USD ($)	Mar. 20, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Five-Year Agreement	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Five-Year Agreement USD ($)	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Euro Facility Agreement EUR (€)
Legal, Guarantees and Indemnifications
Damages sought			$ 200,000,000	$ 125,000,000
Amount of coverage for damages contended by the insurers			50,000,000
Difference amount of damages sought by the client			150,000,000
Maximum potential funding under commitments	71,000,000	104,000,000			45,000,000	450,000,000		400,000,000	650,000,000
Term of credit agreement							5 years
Letters of credit outstanding	71,000,000	74,000,000
Commitments funded					$ 3,000,000