Condensed Consolidating Information (Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Rental income									$ 1,609,876	$ 1,513,807	$ 1,593,598
Income from loans and investments									89,201	124,218	117,608
Income from loans and investments									89,201	124,218	117,608
Equity earnings in affiliates									0	0	0
Interest and other income									10,984	24,892	6,034
Revenues	$ 996,004	$ 983,155	$ 950,717	$ 942,874	$ 923,263	$ 936,538	$ 942,304	$ 943,705	3,872,750	3,745,810	3,574,149
Expenses
Interest									451,662	442,497	448,196
Depreciation and amortization									1,045,620	919,639	887,948
Property-level operating expenses									1,808,208	1,689,880	1,483,072
Office building services costs									2,319	1,418	3,391
General, administrative and professional fees									165,996	151,982	135,490
Loss on extinguishment of debt, net									(41,900)	(58,254)	(754)
Merger-related expenses and deal costs									15,235	30,547	10,535
Other									(17,609)	66,768	20,052
Total expenses									3,513,331	3,360,985	2,989,438
Income (loss) from continuing operations before equity method investments, real estate dispositions, income taxes and noncontrolling interest									359,419	384,825	584,711
Loss from unconsolidated entities									(2,454)	(55,034)	(561)
Gain on real estate dispositions									26,022	46,247	717,273
Income tax benefit									56,310	39,953	59,799
Income from continuing operations	12,893	86,918	211,898	127,588	63,302	103,281	169,300	80,108	439,297	415,991	1,361,222
Discontinued operations					0	0	0	(10)	0	(10)	(110)
Net income	12,893	86,918	211,898	127,588	63,302	103,281	169,300	80,098	439,297	415,981	1,361,112
Net (loss) income attributable to noncontrolling interest, net of tax	1,450	1,659	1,369	1,803	1,029	1,309	2,781	1,395	6,281	6,514	4,642
Net income attributable to common stockholders	$ 11,443	$ 85,259	$ 210,529	$ 125,785	$ 62,273	$ 101,972	$ 166,519	$ 78,703	433,016	409,467	1,356,470
Consolidated Elimination
Revenues
Rental income									0	0	0
Income from loans and investments									0	0
Income from loans and investments											0
Equity earnings in affiliates									(359,674)	(306,068)	(1,265,751)
Interest and other income									0	0	0
Revenues									(359,674)	(306,068)	(1,265,751)
Expenses
Interest									0	0	0
Depreciation and amortization									0	0	0
Property-level operating expenses									0	0	0
Office building services costs									0	0	0
General, administrative and professional fees									0	0	0
Loss on extinguishment of debt, net									0	0	0
Merger-related expenses and deal costs									0	0	0
Other									0	0	0
Total expenses									0	0	0
Income (loss) from continuing operations before equity method investments, real estate dispositions, income taxes and noncontrolling interest									(359,674)	(306,068)	(1,265,751)
Loss from unconsolidated entities									0	0	0
Gain on real estate dispositions									0	0	0
Income tax benefit									0	0	0
Income from continuing operations									(359,674)	(306,068)	(1,265,751)
Discontinued operations										0	0
Net income									(359,674)	(306,068)	(1,265,751)
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(359,674)	(306,068)	(1,265,751)
Ventas, Inc.
Revenues
Rental income									1,074	1,407	2,383
Income from loans and investments									2,812	1,640
Income from loans and investments											1,236
Equity earnings in affiliates									362,143	308,764	1,260,665
Interest and other income									214	23,802	5,388
Revenues									366,243	335,613	1,269,672
Expenses
Interest									(87,222)	(98,411)	(101,385)
Depreciation and amortization									5,686	5,425	5,483
Property-level operating expenses									0	0	0
Office building services costs									0	0	0
General, administrative and professional fees									6,512	(2,866)	2,040
Loss on extinguishment of debt, net									0	(355)	0
Merger-related expenses and deal costs									7,170	25,880	9,796
Other									2,077	4,881	2,247
Total expenses									(65,777)	(64,736)	(81,819)
Income (loss) from continuing operations before equity method investments, real estate dispositions, income taxes and noncontrolling interest									432,020	400,349	1,351,491
Loss from unconsolidated entities									0	0	0
Gain on real estate dispositions									930	6,653	0
Income tax benefit									66	2,475	5,089
Income from continuing operations									433,016	409,477	1,356,580
Discontinued operations										(10)	(110)
Net income									433,016	409,467	1,356,470
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									433,016	409,467	1,356,470
Ventas Realty
Revenues
Rental income									142,562	139,043	178,165
Income from loans and investments									0	0
Income from loans and investments											0
Equity earnings in affiliates									0	0	0
Interest and other income									192	19	0
Revenues									142,754	139,062	178,165
Expenses
Interest									323,860	327,898	319,632
Depreciation and amortization									5,410	5,680	7,510
Property-level operating expenses									578	283	330
Office building services costs									0	0	0
General, administrative and professional fees									17,958	18,845	16,976
Loss on extinguishment of debt, net									(41,875)	(55,910)	(942)
Merger-related expenses and deal costs									0	0	0
Other									2	3	1
Total expenses									389,683	408,619	345,391
Income (loss) from continuing operations before equity method investments, real estate dispositions, income taxes and noncontrolling interest									(246,929)	(269,557)	(167,226)
Loss from unconsolidated entities									0	0	0
Gain on real estate dispositions									88	0	675,808
Income tax benefit									0	0	0
Income from continuing operations									(246,841)	(269,557)	508,582
Discontinued operations										0	0
Net income									(246,841)	(269,557)	508,582
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(246,841)	(269,557)	508,582
Ventas Subsidiaries
Revenues
Rental income									1,466,240	1,373,357	1,413,050
Income from loans and investments									86,389	122,578
Income from loans and investments											116,372
Equity earnings in affiliates									(2,469)	(2,696)	5,086
Interest and other income									10,578	1,071	646
Revenues									3,723,427	3,577,203	3,392,063
Expenses
Interest									215,024	213,010	229,949
Depreciation and amortization									1,034,524	908,534	874,955
Property-level operating expenses									1,807,630	1,689,597	1,482,742
Office building services costs									2,319	1,418	3,391
General, administrative and professional fees									141,526	136,003	116,474
Loss on extinguishment of debt, net									(25)	(1,989)	188
Merger-related expenses and deal costs									8,065	4,667	739
Other									(19,688)	61,884	17,804
Total expenses									3,189,425	3,017,102	2,725,866
Income (loss) from continuing operations before equity method investments, real estate dispositions, income taxes and noncontrolling interest									534,002	560,101	666,197
Loss from unconsolidated entities									(2,454)	(55,034)	(561)
Gain on real estate dispositions									25,004	39,594	41,465
Income tax benefit									56,244	37,478	54,710
Income from continuing operations									612,796	582,139	761,811
Discontinued operations										0	0
Net income									612,796	582,139	761,811
Net (loss) income attributable to noncontrolling interest, net of tax									6,281	6,514	4,642
Net income attributable to common stockholders									606,515	575,625	757,169
Resident Fees and Services
Revenues
Revenue from contracts with customers									2,151,533	2,069,477	1,843,232
Resident Fees and Services | Consolidated Elimination
Revenues
Revenue from contracts with customers									0	0	0
Resident Fees and Services | Ventas, Inc.
Revenues
Revenue from contracts with customers									0	0	0
Resident Fees and Services | Ventas Realty
Revenues
Revenue from contracts with customers									0	0	0
Resident Fees and Services | Ventas Subsidiaries
Revenues
Revenue from contracts with customers									2,151,533	2,069,477	1,843,232
Office Building and Other Services Revenue
Revenues
Revenue from contracts with customers									11,156	13,416	13,677
Office Building and Other Services Revenue | Consolidated Elimination
Revenues
Revenue from contracts with customers									0	0	0
Office Building and Other Services Revenue | Ventas, Inc.
Revenues
Revenue from contracts with customers									0	0	0
Office Building and Other Services Revenue | Ventas Realty
Revenues
Revenue from contracts with customers									0	0	0
Office Building and Other Services Revenue | Ventas Subsidiaries
Revenues
Revenue from contracts with customers									$ 11,156	$ 13,416	$ 13,677