Background and Basis of Presentation (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended			5 Months Ended	9 Months Ended		12 Months Ended
	Aug. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Apr. 29, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Oct. 28, 2021	Jan. 31, 2021	Apr. 30, 2020	Jul. 31, 2019
Equity, Class of Treasury Stock [Line Items]
Payments to acquire additional interest in subsidiaries					$ 250,000,000
Common stock, dividend increase, percentage	4.70%
Dividends declared (usd per share)	$ 0.90	$ 0.90	$ 0.86	$ 0.86		$ 2.62	$ 2.54
Common stock, dividend rate, annual (in usd per share)		$ 3.60				$ 3.60
July 2019 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Planned share repurchase program												$ 1,000,000,000
Stock repurchase program, rescinded authorized repurchase amount											$ 500,000,000
Repurchase of common stock (shares)								0
January 2021 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Planned share repurchase program										$ 2,000,000,000
Repurchase of common stock (shares)		6,700,000				20,200,000
Stock repurchase program, remaining authorized repurchase amount		$ 1,028,000,000				$ 1,028,000,000
January 2021 Share Repurchase Program [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Planned share repurchase program									$ 3,500,000,000
Stock repurchase program, increase authorized amount									$ 1,500,000,000
Helix Innovations LLC [Member]
Equity, Class of Treasury Stock [Line Items]
Subsidiary ownership percentage					100.00%
Noncontrolling interest, remaining interest purchased by parent					20.00%