Investments - Detail of equity method investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule of Investments [Line Items]
Investments accounted for using the equity method	$ 1,407		$ 1,407		$ 1,235
Equity in earnings of partnerships and similar investments	73	$ 36	222	$ 53
Real estate-related investments
Schedule of Investments [Line Items]
Investments accounted for using the equity method	1,024		1,024		915
Equity in earnings of partnerships and similar investments	52	17	151	55
Private equity
Schedule of Investments [Line Items]
Investments accounted for using the equity method	336		336		266
Equity in earnings of partnerships and similar investments	21	21	66	4
Private debt
Schedule of Investments [Line Items]
Investments accounted for using the equity method	47		47		$ 54
Equity in earnings of partnerships and similar investments	$ 0	$ (2)	$ 5	$ (6)