Aggregate dividends declared during the period for each share of common stock outstanding.

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

+ Details

Name:	us-gaap_DividendsCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Dividends (Details) - USD ($) $ / shares in Units, $ in Millions										12 Months Ended
	Mar. 01, 2019	Nov. 14, 2018	Aug. 21, 2018	May 23, 2018	Feb. 21, 2018	Nov. 14, 2017	Aug. 22, 2017	May 24, 2017	Feb. 21, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Dividend per share (usd per share)		$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.540	$ 0.540	$ 0.540	$ 0.540	$ 2.16	$ 2.16	$ 2.16
Total amount declared		$ 586	$ 584	$ 588	$ 586	$ 577	$ 296	$ 297	$ 295
Subsequent event
Subsequent Event [Line Items]
Dividend per share (usd per share)	$ 0.25