Senior Notes Payable and Other Debt - Senior Notes (Details) $ in Thousands, $ in Millions	1 Months Ended				3 Months Ended	12 Months Ended
	Nov. 30, 2019 CAD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2019 CAD ($)	Aug. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 CAD ($)	Oct. 30, 2020 USD ($)	Apr. 30, 2020 USD ($)	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Feb. 28, 2019 USD ($)	Jan. 31, 2019 USD ($)
Debt Instrument [Line Items]
Gain (Loss) on Extinguishment of Debt						$ 10,791	$ 41,900	$ 58,254
Long-term debt, gross						$ 11,983,071	12,245,802
6.90% Senior Notes Due 2037
Debt Instrument [Line Items]
Interest rate						6.90%			6.90%
Six Point Five Nine Percent Senior Notes, Due 2038 [Member]
Debt Instrument [Line Items]
Interest rate						6.59%			6.59%
Long-term debt, gross						$ 22,823	22,823
4.75% Senior Notes due 2030 [Member]
Debt Instrument [Line Items]
Interest rate											4.75%
Senior Notes						500,000	0				$ 500,000
Offering price, percentage of par value											97.86%
3.25% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Interest rate										3.25%
Offering price, percentage of par value										104.14%
Debt instrument, repurchase amount										$ 236,300
Gain (Loss) on Extinguishment of Debt						(11,100)
Five Point Four Five Percent Senior Notes, Due 2043 [Member]
Debt Instrument [Line Items]
Interest rate															5.45%
Debt instrument, repurchase amount															$ 258,800
Gain (Loss) on Extinguishment of Debt					$ (400)			$ (7,100)
4.875% Senior Notes due 2049 [Member]
Debt Instrument [Line Items]
Interest rate														4.875%
Senior Notes						300,000	300,000							$ 300,000
Public offering price as percent of par														99.77%
3.50% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Interest rate														3.50%
Senior Notes						400,000	400,000							$ 400,000
Public offering price as percent of par														99.88%
2.65% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Interest rate													2.65%
Senior Notes						450,000	450,000						$ 450,000
Public offering price as percent of par													99.45%
2.70% Senior Notes, Due 2020
Debt Instrument [Line Items]
Interest rate				2.70%								2.70%
Debt instrument, repurchase amount				$ 102,900								$ 397,100
Gain (Loss) on Extinguishment of Debt				$ (2,400)
Public offering price as percent of par												100.37%
3.00% Senior Notes due 2030 [Member]
Debt Instrument [Line Items]
Interest rate				3.00%
Senior Notes				$ 650,000		$ 650,000	650,000
Public offering price as percent of par				99.51%		8900.00%			8900.00%
Four Point Two Five Percent Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Interest rate		4.25%		4.25%
Debt instrument, repurchase amount		$ 204,300		$ 395,700
Gain (Loss) on Extinguishment of Debt		$ (35,900)
Public offering price as percent of par				105.46%
2.80% Senior Notes, Series E due 2024 [Member]
Debt Instrument [Line Items]
Interest rate	2.80%
Senior Notes	$ 600.0					$ 471,328	462,036
Public offering price as percent of par	99.99%
Floating Rate Series F Due 2021
Debt Instrument [Line Items]
Senior Notes						235,664	$ 231,018
Public offering price as percent of par	100.00%
Repayments of debt	$ 300.0
3.00% Senior Notes, Series A due 2019
Debt Instrument [Line Items]
Interest rate		3.00%
Repayments of debt			$ 400.0
Ventas Realty Limited Partnership | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross						7,700,000
Nationwide Health Properties, LLC | Senior Notes
Debt Instrument [Line Items]
Senior Notes						$ 75,200
Ventas Canada Finance Limited | Senior Notes
Debt Instrument [Line Items]
Senior Notes									$ 1,700.0