Commitments and contingencies (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Performance and surety bonds	$ 56.6	$ 47.4
Letters of credit	$ 0.8	$ 0.5

Amount of performance and surety bonds that are available for the future payment of malpractice claims.

No definition available.

Name:	sdhc_MalpracticeLossContingencyPerformanceAndSuretyBonds
Namespace Prefix:	sdhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant