Shareholders' Equity - Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended	3 Months Ended						12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Jun. 30, 2019
Equity, Class of Treasury Stock [Line Items]
Proceeds from issuance of common stock, net of issuance costs	$ 1,900,000,000
Amount of common stock authorized for repurchase										$ 3,000,000,000	$ 425,000,000	$ 475,000,000
Common stock repurchased		$ 0	$ 0	$ 0
Common Stock
Equity, Class of Treasury Stock [Line Items]
Shares issued (in shares)	21.7
Shares issued (USD per share)	$ 87.60
2019 Program
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase													$ 2,000,000,000
Common stock repurchased					$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 900,000,000	$ 500,000,000