Reinsurance - GMIB Reinsurers (Details) - Guaranteed Minimum Income Benefit [Member] - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Ceded Credit Risk [Line Items]
Annuitization election period	30 days
GMIB Assets	$ 777	$ 799
Berkshire [Member]
Ceded Credit Risk [Line Items]
GMIB Assets	$ 360	370
Berkshire [Member] \| Ceded Credit Risk Secured [Member] \| GMIB Assets [Member]
Ceded Credit Risk [Line Items]
Concentration percentage	100.00%
Sun Life Assurance Company Of Canada [Member]
Ceded Credit Risk [Line Items]
GMIB Assets	$ 220	227
Liberty Re (Bermuda) Ltd. [Member]
Ceded Credit Risk [Line Items]
GMIB Assets	$ 197	$ 202
Liberty Re (Bermuda) Ltd. [Member] \| Ceded Credit Risk Secured [Member] \| GMIB Assets [Member]
Ceded Credit Risk [Line Items]
Concentration percentage	100.00%

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13495-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226008-175313

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