Commitments and Contingencies (Details)	9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended		1 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2012 Five-Year Agreement	May 31, 2010 Opry Mills Mall Limited Partnership USD ($)	Sep. 30, 2012 Commitments to fund certain limited partnerships or subsidiaries USD ($)	Sep. 30, 2012 Commitments to fund certain limited partnerships or subsidiaries USD ($)	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Term Credit Agreement USD ($)	Apr. 30, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Five-Year Agreement	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Five-Year Agreement USD ($)	Apr. 02, 2012 Commitments to fund certain limited partnerships or subsidiaries Subsidiaries Euro Facility Agreement EUR (€)
Legal, Guarantees and Indemnifications
Agreed upon payment in exchange for dismissal of class claims	$ 550,000
Damages sought by Opry Mills Mall Limited Partnership			200,000,000
Amount of coverage for damages contended by the insurers			50,000,000
Difference amount of damages sought by the client			150,000,000
Estimated exposure with respect to contractual contingent guarantees for premium payments owed by clients	36,000,000
Maximum potential funding under commitments				55,000,000	55,000,000	450,000,000		400,000,000	650,000,000
Term of credit agreement		5 years					5 years
Commitments funded				$ 4,000,000	$ 8,000,000