New Accounting Standards (Details) - Accounting Standards Update 2016-01 [Member] $ in Millions	Dec. 31, 2017 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earning and investments in unconsolidated subsidiaries and equity securities	$ 238
Cumulative effect on retained earning and investments in unconsolidated subsidiaries and equity securities, tax amount	$ 63

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

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