Capital structure and noncontrolling interests - Summary of Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	$ 41	$ 43	$ 256	$ 349
Distributions				(1)
Redemption of redeemable noncontrolling interests	(28)			(6)
Expiration of redemption option	(6)			(92)
Redeemable noncontrolling interest redemption value adjustment		(2)	4	6
Redeemable noncontrolling interest redemption value adjustment			2	6
Balance, end of period	7	41	262	256
Operating Partnership Units
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	34	32	27	120
Distributions				(1)
Redemption of redeemable noncontrolling interests	(28)			(6)
Expiration of redemption option	(6)			(92)
Redeemable noncontrolling interest redemption value adjustment		2	0	6
Redeemable noncontrolling interest redemption value adjustment			1
Balance, end of period	0	34	28	27
Preference Shares
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	0	0	221	221
Distributions				0
Redemption of redeemable noncontrolling interests	0			0
Expiration of redemption option	0			0
Redeemable noncontrolling interest redemption value adjustment		0	4	0
Redeemable noncontrolling interest redemption value adjustment			0
Balance, end of period	0	0	225	221
Operating Subsidiaries
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	7	11	8	8
Distributions				0
Redemption of redeemable noncontrolling interests	0			0
Expiration of redemption option	0			0
Redeemable noncontrolling interest redemption value adjustment		(4)	0	0
Redeemable noncontrolling interest redemption value adjustment			1
Balance, end of period	$ 7	$ 7	$ 9	$ 8