Organization Review Costs by Reportable Segment (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	$ 19
Specialty [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	4
Commercial [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	14
International [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	0
Life and Group Non-Core [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	1
Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs	$ 0

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Name:	us-gaap_RestructuringCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration