Summary of Significant Accounting Policies - Narrative (Details)		3 Months Ended			9 Months Ended		12 Months Ended
		Sep. 30, 2020 USD ($) d facility	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) d facility	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) property
Property, Plant and Equipment [Line Items]
Federal COVID-19 provider relief funds received		$ 600,000	$ 800,000		$ 1,400,000
Variable Interest Entities
Assets of consolidated VIEs	[1]	2,007,962,000			2,007,962,000		$ 2,141,207,000
Liabilities of consolidated VIEs	[1]	1,505,915,000			1,505,915,000		$ 1,473,703,000
Finance Lease Obligations
Finance leases for equipment		$ 3,500,000			3,500,000
Payments of finance lease obligations					$ 500,000	$ 500,000
Weighted average interest rate (percent)		6.20%			6.20%
Remaining lease term (years)		2 years 7 months 6 days			2 years 7 months 6 days
Identified Intangibles
Fair value in excess of carrying amount (less than)		5.00%	5.00%		5.00%
Amortization expense for in-place leases and deferred costs					$ 1,400,000	7,800,000
Acquisition Fees and Expenses
Acquisition fee and expense cap		6.00%			6.00%
Days notice required for lease termination | d		30			30
Variable lease revenues		$ 2,600,000		$ 4,200,000	$ 10,900,000	12,300,000
Concession period (days)					90 days
Repayment period (months)					12 months
Payments deferred		3,900,000			$ 3,900,000
Investments in Unconsolidated Ventures
Impairment loss		0		0	91,437,000	10,146,000
Impairment recognized					0
Impairment of affiliate properties					37,800,000
Income Taxes
Deferred tax asset		20,200,000			20,200,000
Income tax expense		$ 15,000		$ 17,000	$ 43,000	$ 38,000
Minimum | Terminal capitalization rate | Discounted cash flow method
Identified Intangibles
Goodwill impairment measurement input		6.50%			6.50%
Minimum | Discount rate | Discounted cash flow method
Identified Intangibles
Goodwill impairment measurement input		7.75%			7.75%
Maximum | Terminal capitalization rate | Discounted cash flow method
Identified Intangibles
Goodwill impairment measurement input		7.75%			7.75%
Maximum | Discount rate | Discounted cash flow method
Identified Intangibles
Goodwill impairment measurement input		9.25%			9.25%
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entities
VIE carrying value		$ 230,300,000			$ 230,300,000
Peregrine
Finance Lease Obligations
Number of properties held for sale | property							1
Investments in Unconsolidated Ventures
Impairment loss					700,000
Winterfell
Investments in Unconsolidated Ventures
Impairment loss					$ 70,800,000
Properties | facility		8			8
Aqua
Investments in Unconsolidated Ventures
Impairment loss					$ 19,900,000
Griffin-American
Investments in Unconsolidated Ventures
Impairment of affiliate properties					34,100,000
Eclipse
Investments in Unconsolidated Ventures
Impairment of affiliate properties					3,100,000
Trilogy
Investments in Unconsolidated Ventures
Impairment of affiliate properties					600,000
Leases, Acquired-in-Place
Identified Intangibles
In-place lease value, gross		$ 130,000,000.0			130,000,000.0
In-place lease value, accumulated amortization		(125,000,000.0)			(125,000,000.0)
Variable Interest Entity, Primary Beneficiary | Operating Real Estate
Variable Interest Entities
Assets of consolidated VIEs		553,200,000			553,200,000
Variable Interest Entity, Primary Beneficiary | Mortgage Notes Payable
Variable Interest Entities
Liabilities of consolidated VIEs		$ 460,500,000			$ 460,500,000

[1] Represents the consolidated assets and liabilities of NorthStar Healthcare Income Operating Partnership, LP (the “Operating Partnership”). The Operating Partnership is a consolidated variable interest entity (“VIE”), of which the Company is the sole general partner and owns approximately 99.99%. As of September 30, 2020, the Operating Partnership includes $0.6 billion and $0.5 billion of assets and liabilities, respectively, of certain VIEs that are consolidated by the Operating Partnership. Refer to Note 2, “Summary of Significant Accounting Policies.”