Describes the terms of arrangements (for example, liquidity arrangements, guarantees, or other commitments) by third parties that may affect the fair value or risk of the reporting entity's variable interest in the Variable Interest Entity (VIE).

Name:	us-gaap_LiquidityArrangementsGuaranteesAndOtherCommitmentsByThirdParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Difference between the carrying amount of assets and liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the variable interest entity (VIE) and the reporting entity's maximum exposure to loss as a result of its involvement with the VIE, where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

Name:	us-gaap_VariableInterestDifferenceBetweenCarryingAmountAndMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5710-111685

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssetsAndLiabilitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

+ Details

Name:	us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_VariableInterestEntityNonconsolidatedComparisonOfCarryingAmountOfAssetsAndLiabilitiesToMaximumLossExposureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Investment Holding Level 4 Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2016	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure [Abstract]
Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure		$ 1,800	$ 1,700
Variable Interest Entity, Commitments by Third Parties, Liquidity and Other Arrangements	As of September 30, 2017 and December 31, 2016, the Company has outstanding commitments totaling $1.0 billion and $1.2 billion, respectively, whereby the Company is committed to fund these investments and may be called by the partnership during the commitment period to fund the purchase of new investments and partnership expenses.	As of September 30, 2017 and December 31, 2016, the Company has outstanding commitments totaling $1.0 billion and $1.2 billion, respectively, whereby the Company is committed to fund these investments and may be called by the partnership during the commitment period to fund the purchase of new investments and partnership expenses.
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			3
Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure [Abstract]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets			1
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities			3
Collateralized Debt Obligations [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entity, Consolidated, Carrying Amount, Assets			5
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities			5
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			$ 0