Acquisitions, Dispositions, and Other Significant Leasing Transactions - Welltower Lease Amendments (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) community lease	Dec. 31, 2023 USD ($) community	Dec. 31, 2022 USD ($)
Business Acquisition [Line Items]
Operating lease right-of-use assets		$ 670,907	$ 597,130
Mortgages
Business Acquisition [Line Items]
Operating lease, covenant provisions, required minimum tangible net worth		2,000,000
Welltower Inc.
Business Acquisition [Line Items]
Number of communities company continues to lease | community	74
Number of communities leased | community	69
Maximum fund costs	$ 17,000
Operating lease right-of-use assets		122,300
Operating lease, covenant provisions, required minimum stockholders equity		400,000
Welltower Inc. | Mortgages
Business Acquisition [Line Items]
Operating lease, covenant provisions, required minimum tangible net worth		$ 1,500,000
Welltower Inc. | Revision of Prior Period, Reclassification, Adjustment
Business Acquisition [Line Items]
Number of communities leased | community		35
Lease expense		$ 19,300
Welltower Inc. | Lease Expire From December 31, 2026 Until June 30, 2032
Business Acquisition [Line Items]
Number of leases extended | lease	1
Number of communities leased | community	39
Welltower Inc. | Lease Expire On June 30, 2032
Business Acquisition [Line Items]
Number of communities leased | community	69
Welltower Inc. | Lease Expire On December 31, 2024
Business Acquisition [Line Items]
Number of communities leased | community	5
Welltower Inc. | Minimum Rent Leasing Arrangement | Secured Overnight Financing Rate (SOFR)
Business Acquisition [Line Items]
Annual escalator rate (as percent)	4.00%
Welltower Inc. | Minimum Rent Leasing Arrangement | Minimum | Secured Overnight Financing Rate (SOFR)
Business Acquisition [Line Items]
Annual escalator rate (as percent)	3.00%