Consolidated Statements of Shareholders' Equity (Parentheticals) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Treasury shares held in trust (in shares)	1	1	1
Treasury shares held in trust	$ 31	$ 29	$ 31
Common stock	17	$ 17	$ 17
Net income attributable to noncontrolling interest	$ 1

Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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