Commitments and Contingencies (Details)					3 Months Ended	6 Months Ended			0 Months Ended			0 Months Ended
	Jun. 30, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jun. 30, 2014 Potential Claim for Pension Advisory Services [Member] USD ($)	Jun. 30, 2014 Potential Claim for Pension Advisory Services [Member] GBP (£)	Jun. 30, 2014 Commitments to fund certain limited partnerships or subsidiaries [Member] USD ($)	Jun. 30, 2014 Commitments to fund certain limited partnerships or subsidiaries [Member] USD ($)	Dec. 31, 2013 Commitments to fund certain limited partnerships or subsidiaries [Member] USD ($)	Jun. 15, 2011 Commitments to fund certain limited partnerships or subsidiaries [Member] Subsidiaries [Member] Term Credit Agreement [Member] USD ($)	Mar. 20, 2012 Commitments to fund certain limited partnerships or subsidiaries [Member] Subsidiaries [Member] Five-Year Agreement [Member]	Mar. 20, 2012 Commitments to fund certain limited partnerships or subsidiaries [Member] Subsidiaries [Member] Five-Year Agreement [Member] USD ($)	Oct. 15, 2010 Commitments to fund certain limited partnerships or subsidiaries [Member] Subsidiaries [Member] Euro Facility Agreement [Member] EUR (€)	Sep. 14, 2010 Opry Mills Mall Limited Partnership [Member] USD ($)	Jan. 02, 2014 Philips [Member] USD ($)	Jan. 02, 2014 Philips [Member] GBP (£)	Jan. 02, 2014 Northrop Grumman Corporation [Member] USD ($)	Dec. 27, 2012 Versicherung Aktiengesellschaft [Member] Litigation Award [Member] USD ($)	Dec. 27, 2012 Versicherung Aktiengesellschaft [Member] Litigation Award [Member] EUR (€)	Jun. 01, 2007 International Road Transport Union [Member] Litigation USD Denominated Award [Member] USD ($)	Jun. 01, 2007 International Road Transport Union [Member] Litigation Award [Member] USD ($)	Jun. 01, 2007 International Road Transport Union [Member] Litigation Award [Member] CHF	Jun. 01, 2007 International Road Transport Union [Member] Litigation Expenses and Interest [Member] USD ($)	Dec. 12, 2012 Mazeikiu Nafta [Member] USD ($)
Legal, Guarantees and Indemnifications
Loss Contingency, Range of Possible Loss, Minimum	$ 0
Loss Contingency, Range of Possible Loss, Maximum	700,000,000
Damages sought												200,000,000	322,000,000	189,000,000	340,000,000	250,000,000	183,000,000	3,000,000	51,000,000	46,000,000	30,000,000	125,000,000
Loss Contingency, Estimate of Possible Loss			77,000,000	45,000,000
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	92,000,000	98,000,000			20,000,000	20,000,000	34,000,000	450,000,000		400,000,000	650,000,000
Term of credit agreement									5 years
Letters of credit outstanding	98,000,000	71,000,000
Commitments funded					$ 4,000,000	$ 14,000,000