Consolidated Statements of Cash Flows Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Net Cash Provided by (Used in) Investing Activities [Abstract]
Cash disposed from sale of businesses	$ 0	$ 135

Reduction in cash due to no longer including the former subsidiary's cash in the consolidated entity's cash.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

Name:	us-gaap_CashDivestedFromDeconsolidation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration