Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Segment Information (Narrative) (Details) $ in Millions	3 Months Ended			9 Months Ended
Segment Information (Narrative) (Details) $ in Millions	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) division segment	Sep. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Income (loss) before income taxes and equity in earnings of operating joint ventures	$ 3,021	$ 2,315		$ 5,371	$ 5,388
Number of operating divisions \| division				4
Number of reportable segments \| segment				7
Individual Life \| Out of period adjustment
Segment Reporting Information [Line Items]
Income (loss) before income taxes and equity in earnings of operating joint ventures			$ (148)		$ (148)