Investment in Unconsolidated Ventures - Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Operations Information
Resident fee revenue	$ 436	$ 793	$ 1,354
Facility operating expense	(330)	(592)	(946)
Net income (loss)	(9)	(39)	$ (81)
Balance Sheet Information
Current assets	68	66
Noncurrent assets	1,100	1,148
Current liabilities	537	563
Noncurrent liabilities	$ 735	$ 715