Amount of the cumulative effect on retained earnings net of related income tax effect.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Name:	us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Significant Accounting Policies - Adoption of ASC 842 on Unaudited Condensed Consolidated Balance Sheet (Parenthetical) (Details) - USD ($) $ in Millions		9 Months Ended
	Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Recorded a net increase in opening retained earnings		$ 3	$ 4
Accounting Standards Update 2016-02 \| Adjustments Due to ASC 842
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Recorded a net increase in opening retained earnings	$ 3