Business (Details) $ / shares in Units, shares in Millions, ft² in Millions		3 Months Ended	12 Months Ended	135 Months Ended	136 Months Ended
	Apr. 22, 2025 USD ($) $ / shares	Mar. 31, 2024 USD ($) property	Dec. 31, 2024 USD ($) $ / shares	Mar. 31, 2025 USD ($) ft² trustee parcel shares	Apr. 22, 2025 USD ($) $ / shares	Nov. 15, 2024 $ / shares
Noncontrolling Interest [Line Items]
Cash and cash equivalents			$ 160,511,000	$ 227,271,000
Cumulative liquidating distributions (in dollars per share) | $ / shares			$ 19.00			$ 19.00
Cumulative liquidating distributions			$ 2,000,000,000.0
Number of properties sold		0		168
Number of land parcels sold | parcel				3
Area of real estate property | ft²				45.8
Gross sale price				$ 7,200,000,000
Retired debt and preferred shares				3,400,000,000
Repurchased common shares				$ 652,100,000
Distributions		$ 1,752,000
Select Income REIT Common Stock
Noncontrolling Interest [Line Items]
Common stock issued (in shares) | shares				704.8
Subsequent event
Noncontrolling Interest [Line Items]
Cumulative liquidating distributions (in dollars per share) | $ / shares	$ 1.60				$ 1.60
Cumulative aggregate liquidating distributions (in dollars per share) | $ / shares	$ 20.60				$ 20.60
Cumulative liquidating distributions	$ 172,400,000
Distributions					$ 4,000,000,000
Operating Trust
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by parent				99.86%