Equity Equity (Common Stock Dividends) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Dividends Payable [Line Items]
Dividends, Common Stock, Cash	$ 413			$ 419			$ 824	$ 844
Common Stock [Member]
Dividends Payable [Line Items]
Dividends Payable, Date Declared	Jul. 08, 2019	Apr. 23, 2019	Jan. 07, 2019	Jul. 06, 2018	Apr. 24, 2018	Jan. 05, 2018
Dividends Payable, Date of Record	Aug. 06, 2019	May 07, 2019	Feb. 05, 2019	Aug. 06, 2018	May 07, 2018	Feb. 05, 2018
Dividends Payable, Date to be Paid	Sep. 13, 2019	Jun. 13, 2019	Mar. 13, 2019	Sep. 13, 2018	Jun. 13, 2018	Mar. 13, 2018
Common Stock, Dividends, Per Share, Cash Paid	$ 0.440	$ 0.440	$ 0.420	$ 0.420	$ 0.420	$ 0.400
Dividends, Common Stock, Cash	$ 413	$ 419	$ 405	$ 419	$ 428	$ 416			$ 1,237	$ 1,263

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

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

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