Intangibles - Narrative (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Weighted average remaining amortization period in years	6 years	5 years
Weighted average remaining amortization period in years	8 years	8 years
Brookedale MTCA
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 81	$ 352
Intangible liabilities acquired	$ 17	$ 83
Weighted average remaining amortization period in years	9 years	7 years
Weighted average remaining amortization period in years	8 years	9 years