Senior Notes and Other Debt (Senior Notes) (Details) $ in Thousands, $ in Millions	1 Months Ended							3 Months Ended		12 Months Ended
	Nov. 30, 2019 CAD ($)	Sep. 30, 2019 CAD ($)	Aug. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Aug. 31, 2018 USD ($)	Apr. 30, 2018 USD ($)	Feb. 28, 2018 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 CAD ($)	Jul. 01, 2019 USD ($)	Feb. 28, 2019 USD ($)	Jan. 31, 2019 USD ($)	Jan. 03, 2019
Debt Instrument [Line Items]
Loss on extinguishment of debt, net										$ 41,900	$ 58,254	$ 754
Senior Notes | Ventas Realty Limited Partnership
Debt Instrument [Line Items]
Senior notes										7,500,000
Senior Notes | Ventas Realty and Ventas Capital Corp [Member]
Debt Instrument [Line Items]
Senior notes										500,000
Senior Notes | Nationwide Health Properties, LLC
Debt Instrument [Line Items]
Senior notes										75,200
Senior Notes | Ventas Canada Finance Limited
Debt Instrument [Line Items]
Senior notes													$ 1,700
6.90% Senior Notes due 2037
Debt Instrument [Line Items]
Senior notes										$ 52,400	52,400
Interest rate										6.90%			6.90%
6.59% Senior Notes due 2038
Debt Instrument [Line Items]
Senior notes										$ 22,823	22,823
Interest rate										6.59%			6.59%
5.45% Senior Notes due 2043
Debt Instrument [Line Items]
Senior notes										$ 0	258,750
Interest rate										5.45%			5.45%				5.45%
Debt instrument, repurchase amount																$ 258,800
Loss on extinguishment of debt, net									$ 400		7,100
3.50% Senior Notes due 2024
Debt Instrument [Line Items]
Senior notes										$ 400,000	0				$ 400,000
Interest rate										3.50%			3.50%		3.50%
Public offering price as percent of par															99.88%
4.875% Senior Notes due 2049
Debt Instrument [Line Items]
Senior notes										$ 300,000	0				$ 300,000
Interest rate										4.875%			4.875%		4.875%
Public offering price as percent of par															99.77%
2.65% Senior Notes due 2025
Debt Instrument [Line Items]
Senior notes										$ 450,000	0			$ 450,000
Interest rate										2.65%			2.65%	2.65%
Public offering price as percent of par														99.45%
2.70% Senior Notes due 2020
Debt Instrument [Line Items]
Senior notes										$ 0	500,000
Interest rate			2.70%							2.70%			2.70%	2.70%
Debt instrument, repurchase amount			$ 102,900											$ 397,100
Loss on extinguishment of debt, net			2,400
Public offering price as percent of par														100.37%
3.00% Senior Notes due 2030
Debt Instrument [Line Items]
Senior notes			$ 650,000							$ 650,000	0
Interest rate			3.00%							3.00%			3.00%
Public offering price as percent of par			99.51%
4.25% Senior Notes due 2022
Debt Instrument [Line Items]
Senior notes										$ 0	600,000
Interest rate			4.25%					4.25%		4.25%			4.25%
Debt instrument, repurchase amount			$ 395,700					$ 204,300
Loss on extinguishment of debt, net								$ 35,900
Public offering price as percent of par			105.46%
3.00% Senior Notes, Series A due 2019
Debt Instrument [Line Items]
Senior notes										$ 0	293,319
Interest rate								3.00%		3.00%			3.00%
Repayments of debt		$ 400
2.80% Senior Notes, Series E due 2024
Debt Instrument [Line Items]
Senior notes	$ 600									$ 462,036	0
Interest rate	2.80%									2.80%			2.80%
Public offering price as percent of par	99.99%
Floating Rate, Series F due 2021
Debt Instrument [Line Items]
Senior notes										$ 231,018	0
Public offering price as percent of par	100.00%
Repayments of debt	$ 300
2.00% Senior Notes, Due 2018
Debt Instrument [Line Items]
Interest rate							2.00%
Repayments of debt							$ 700,000
4.00% Senior Notes due 2028
Debt Instrument [Line Items]
Senior notes							$ 650,000			$ 650,000	650,000
Interest rate							4.00%			4.00%			4.00%
Public offering price as percent of par							99.23%
Four Percent, Senior Notes, Due 2019 [Member]
Debt Instrument [Line Items]
Interest rate						4.00%	4.00%
Debt instrument, repurchase amount							$ 502,100
Loss on extinguishment of debt, net						$ 1,800	$ 11,000
Public offering price as percent of par							101.83%
Repayments of debt						$ 97,900
4.40% Senior Notes due 2029
Debt Instrument [Line Items]
Senior notes					$ 750,000					$ 750,000	$ 750,000
Interest rate					4.40%					4.40%			4.40%
Public offering price as percent of par					99.95%
4.750% Senior Notes, due 2021
Debt Instrument [Line Items]
Interest rate				4.75%	4.75%
Debt instrument, repurchase amount					$ 549,500
Loss on extinguishment of debt, net				$ 7,600	$ 28,300
Public offering price as percent of par					104.56%
Repayments of debt				$ 150,500