Consolidated Investment Entities - Fair Value Hierarchy (Details) - Assets measured on recurring basis - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Asset Value (NAV)	$ 1,795	$ 1,829
Investments, Including Net Asset Value, Fair Value Disclosure	3,101	4,022
Liabilities	1,047	1,967
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	217	133
Liabilities	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,089	2,045
Liabilities	1,047	1,967
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	15
Liabilities	0	0
VIEs | Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	216	133
VIEs | Cash and cash equivalents | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	216	133
VIEs | Cash and cash equivalents | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VIEs | Cash and cash equivalents | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VIEs | Corporate loans, at fair value using the fair value option
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,089	1,921
VIEs | Corporate loans, at fair value using the fair value option | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VIEs | Corporate loans, at fair value using the fair value option | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1,089	1,906
VIEs | Corporate loans, at fair value using the fair value option | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	15
VIEs | Limited Partnerships/Corporations, at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Asset Value (NAV)	1,714	1,770
Investments, Including Net Asset Value, Fair Value Disclosure	1,714	1,770
VIEs | Limited Partnerships/Corporations, at fair value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0
VIEs | Limited Partnerships/Corporations, at fair value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VIEs | Limited Partnerships/Corporations, at fair value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VIEs | CLO notes, at fair value using the fair value option
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	1,047	1,967
VIEs | CLO notes, at fair value using the fair value option | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	0	0
VIEs | CLO notes, at fair value using the fair value option | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	1,047	1,967
VIEs | CLO notes, at fair value using the fair value option | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities	0	0
VOEs | Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1	0
VOEs | Cash and cash equivalents | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	1	0
VOEs | Cash and cash equivalents | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VOEs | Cash and cash equivalents | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VOEs | Corporate loans, at fair value using the fair value option
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	32
VOEs | Corporate loans, at fair value using the fair value option | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VOEs | Corporate loans, at fair value using the fair value option | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	32
VOEs | Corporate loans, at fair value using the fair value option | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VOEs | Limited Partnerships/Corporations, at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Asset Value (NAV)	81	59
Investments, Including Net Asset Value, Fair Value Disclosure	81	166
VOEs | Limited Partnerships/Corporations, at fair value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	0
VOEs | Limited Partnerships/Corporations, at fair value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	0	107
VOEs | Limited Partnerships/Corporations, at fair value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets	$ 0	$ 0