Capital Transactions - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions					3 Months Ended		9 Months Ended
	May 06, 2021	Feb. 04, 2021	May 06, 2020	Feb. 06, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Dividends per common share (in dollars per share)		$ 0.47		$ 0.41	$ 0.47	$ 0.41
Cash dividend payment	$ 365		$ 316				$ 365	$ 316