Condensed Consolidating Information (Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Rental income									$ 1,513,807	$ 1,593,598	$ 1,476,176
Income from loans and investments									124,218	117,608	98,094
Equity earnings in affiliates									0	0	0
Interest and other income									24,892	6,034	876
Revenues	$ 923,263	$ 936,538	$ 942,304	$ 943,705	$ 895,288	$ 899,928	$ 895,490	$ 883,443	3,745,810	3,574,149	3,443,522
Expenses
Interest									442,497	448,196	419,740
Depreciation and amortization									919,639	887,948	898,924
Property-level operating expenses									1,689,880	1,483,072	1,434,762
Office building services costs									1,418	3,391	7,311
General, administrative and professional fees									151,982	135,490	126,875
Loss on extinguishment of debt, net									58,254	754	2,779
Merger-related expenses and deal costs									30,547	10,535	24,635
Other									66,768	20,052	9,988
Total expenses									3,360,985	2,989,438	2,925,014
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests									384,825	584,711	518,508
Loss from unconsolidated entities									(55,034)	(561)	4,358
Gain on real estate dispositions									46,247	717,273	98,203
Income tax benefit									39,953	59,799	31,343
Income from continuing operations	63,302	103,281	169,300	80,108	393,820	615,210	152,991	199,201	415,991	1,361,222	652,412
Discontinued operations	0	0	0	(10)	(15)	(19)	(23)	(53)	(10)	(110)	(922)
Net income	63,302	103,281	169,300	80,098	393,805	615,191	152,968	199,148	415,981	1,361,112	651,490
Net (loss) income attributable to noncontrolling interest, net of tax	1,029	1,309	2,781	1,395	1,251	1,233	1,137	1,021	6,514	4,642	2,259
Net income attributable to common stockholders	$ 62,273	$ 101,972	$ 166,519	$ 78,703	$ 392,554	$ 613,958	$ 151,831	$ 198,127	409,467	1,356,470	649,231
Consolidated Elimination
Revenues
Rental income									0	0	0
Income from loans and investments									0	0	0
Equity earnings in affiliates									(306,068)	(1,265,751)	(626,041)
Interest and other income									0	0	0
Revenues									(306,068)	(1,265,751)	(626,041)
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 before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests									(306,068)	(1,265,751)	(626,041)
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									(306,068)	(1,265,751)	(626,041)
Discontinued operations									0	0	0
Net income									(306,068)	(1,265,751)	(626,041)
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(306,068)	(1,265,751)	(626,041)
Ventas, Inc.
Revenues
Rental income									1,407	2,383	2,670
Income from loans and investments									1,640	1,236	341
Equity earnings in affiliates									308,764	1,260,665	626,644
Interest and other income									23,802	5,388	665
Revenues									335,613	1,269,672	631,925
Expenses
Interest									(98,411)	(101,385)	(46,820)
Depreciation and amortization									5,425	5,483	8,968
Property-level operating expenses									0	0	0
Office building services costs									0	0	0
General, administrative and professional fees									(2,866)	2,040	498
Loss on extinguishment of debt, net									355	0	58
Merger-related expenses and deal costs									25,880	9,796	23,067
Other									4,881	2,247	(705)
Total expenses									(64,736)	(81,819)	(14,934)
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests									400,349	1,351,491	646,859
Loss from unconsolidated entities									0	0	0
Gain on real estate dispositions									6,653	0	299
Income tax benefit									2,475	5,089	2,994
Income from continuing operations									409,477	1,356,580	650,152
Discontinued operations									(10)	(110)	(921)
Net income									409,467	1,356,470	649,231
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									409,467	1,356,470	649,231
Ventas Realty
Revenues
Rental income									139,043	178,165	196,991
Income from loans and investments									0	0	0
Equity earnings in affiliates									0	0	0
Interest and other income									19	0	0
Revenues									139,062	178,165	196,991
Expenses
Interest									327,898	319,632	281,458
Depreciation and amortization									5,680	7,510	18,297
Property-level operating expenses									283	330	317
Office building services costs									0	0	0
General, administrative and professional fees									18,845	16,976	18,320
Loss on extinguishment of debt, net									55,910	942	2,711
Merger-related expenses and deal costs									0	0	0
Other									3	1	41
Total expenses									408,619	345,391	321,144
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests									(269,557)	(167,226)	(124,153)
Loss from unconsolidated entities									0	0	0
Gain on real estate dispositions									0	675,808	63,821
Income tax benefit									0	0	0
Income from continuing operations									(269,557)	508,582	(60,332)
Discontinued operations									0	0	0
Net income									(269,557)	508,582	(60,332)
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(269,557)	508,582	(60,332)
Ventas Subsidiaries
Revenues
Rental income									1,373,357	1,413,050	1,276,515
Income from loans and investments									122,578	116,372	97,753
Equity earnings in affiliates									(2,696)	5,086	(603)
Interest and other income									1,071	646	211
Revenues									3,577,203	3,392,063	3,240,647
Expenses
Interest									213,010	229,949	185,102
Depreciation and amortization									908,534	874,955	871,659
Property-level operating expenses									1,689,597	1,482,742	1,434,445
Office building services costs									1,418	3,391	7,311
General, administrative and professional fees									136,003	116,474	108,057
Loss on extinguishment of debt, net									1,989	(188)	10
Merger-related expenses and deal costs									4,667	739	1,568
Other									61,884	17,804	10,652
Total expenses									3,017,102	2,725,866	2,618,804
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests									560,101	666,197	621,843
Loss from unconsolidated entities									(55,034)	(561)	4,358
Gain on real estate dispositions									39,594	41,465	34,083
Income tax benefit									37,478	54,710	28,349
Income from continuing operations									582,139	761,811	688,633
Discontinued operations									0	0	(1)
Net income									582,139	761,811	688,632
Net (loss) income attributable to noncontrolling interest, net of tax									6,514	4,642	2,259
Net income attributable to common stockholders									575,625	757,169	686,373
Resident Fees and Services
Revenues
Revenue from contracts with customers									2,069,477	1,843,232	1,847,306
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									2,069,477	1,843,232	1,847,306
Office Building and Other Services Revenue
Revenues
Revenue from contracts with customers									13,416	13,677	21,070
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	1,605
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									$ 13,416	$ 13,677	$ 19,465