Capital structure and noncontrolling interests - Schedule of Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2026	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Jun. 30, 2026
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	$ 7	$ 41	$ 43	$ 43
Redeemable noncontrolling interest redemption value adjustment			(2)
Redemption of redeemable noncontrolling interests	(7)	(28)
Expiration of redemption option		(6)
Balance, end of period	0	7	41	7
Redeemable noncontrolling interests	0	7	41	7	$ 0
Operating Partnership Units
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period		34	32	32
Redeemable noncontrolling interest redemption value adjustment			2
Redemption of redeemable noncontrolling interests		(28)
Expiration of redemption option		(6)
Balance, end of period		0	34	0
Redeemable noncontrolling interests		0	34	0
Operating Subsidiaries
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of period	7	7	11	11
Redeemable noncontrolling interest redemption value adjustment			(4)	(4)
Redemption of redeemable noncontrolling interests	(7)	0
Expiration of redemption option		0
Balance, end of period	0	7	7	7
Redeemable noncontrolling interests	$ 0	$ 7	$ 7	$ 7	$ 0

Carrying amount, attributable to parent and noncontrolling interests, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details