Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Indemnity
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 30
Description of commitment: contractual commitment to invest in limited partnership investments	Contractual commitments to invest in limited partnership investments, consisting of private equity securities, mezzanine debt securities, and real estate activities.
Indemnity | Private equity
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	14
Indemnity | Mezzanine debt
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	10
Indemnity | Real estate
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	6
Exchange
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	388
Description of commitment: contractual commitment to invest in limited partnership investments	Contractual commitments to invest in limited partnership investments, consisting of private equity securities, mezzanine debt securities, and real estate activities.
Exchange | Private equity
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	137
Exchange | Mezzanine debt
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	164
Exchange | Real estate
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 87