CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Rental income	$ 398,570	$ 360,262	$ 800,066	$ 745,071
Income from loans and investments	19,529	56,417	36,655	87,598
Equity earnings in affiliates	0	0	0	0
Interest and other income	9,202	2,347	9,489	11,981
Total revenues	950,717	942,304	1,893,591	1,886,009
Expenses
Interest	110,369	113,029	220,988	224,392
Depreciation and amortization	226,187	223,634	462,107	456,784
Property-level operating expenses	435,901	421,413	866,405	834,326
Office building services costs	515	534	1,148	649
General, administrative and professional fees	43,079	36,656	83,839	73,830
Loss on extinguishment of debt, net	4,022	(93)	4,427	10,884
Merger-related expenses and deal costs	4,600	4,494	6,780	21,830
Other	(11,481)	3,527	(11,458)	6,647
Total expenses	813,192	803,194	1,634,236	1,629,342
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	137,525	139,110	259,355	256,667
Loss from unconsolidated entities	(2,529)	(6,371)	(3,475)	(47,110)
Gain on real estate dispositions	19,150	35,827	24,597	35,875
Income from continuing operations	211,898	169,300	339,486	249,408
Discontinued operations	0	0	0	(10)
Income tax benefit	57,752	734	59,009	3,976
Net income	211,898	169,300	339,486	249,398
Net income attributable to noncontrolling interests	1,369	2,781	3,172	4,176
Net income attributable to common stockholders	210,529	166,519	336,314	245,222
Resident Fees and Services
Revenues:
Other revenues	520,725	518,989	1,042,172	1,033,742
Office Building and Other Services Revenue
Revenues:
Other revenues	2,691	4,289	5,209	7,617
Consolidated Elimination
Revenues:
Rental income	0	0	0	0
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	(202,261)	(143,197)	(299,534)	(202,849)
Interest and other income	0	0	0	0
Total revenues	(202,261)	(143,197)	(299,534)	(202,849)
Expenses
Interest	0	0	0	0
Depreciation and amortization	0	0	0	0
Property-level operating expenses	0	0	0	0
Office building services costs	0	0	0	0
General, administrative and professional fees	0	0	0	0
Loss on extinguishment of debt, net	0	0	0	0
Merger-related expenses and deal costs	0	0	0	0
Other	0	0	0	0
Total expenses	0	0	0	0
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	(202,261)	(143,197)	(299,534)	(202,849)
Loss from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	0	0	0	0
Income from continuing operations	(202,261)	(143,197)	(299,534)	(202,849)
Discontinued operations	0	0	0	0
Income tax benefit	0	0	0	0
Net income	(202,261)	(143,197)	(299,534)	(202,849)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(202,261)	(143,197)	(299,534)	(202,849)
Consolidated Elimination | Resident Fees and Services
Revenues:
Other revenues	0	0	0	0
Consolidated Elimination | Office Building and Other Services Revenue
Revenues:
Other revenues	0	0	0	0
Ventas, Inc.
Revenues:
Rental income	268	255	534	856
Income from loans and investments	736	272	1,159	763
Equity earnings in affiliates	202,825	143,760	300,660	204,055
Interest and other income	9	2,069	21	11,391
Total revenues	203,838	146,356	302,374	217,065
Expenses
Interest	(17,672)	(28,295)	(38,343)	(56,990)
Depreciation and amortization	1,460	1,373	2,812	2,717
Property-level operating expenses	0	0	0	0
Office building services costs	0	0	0	0
General, administrative and professional fees	7,079	(409)	(1,589)	148
Loss on extinguishment of debt, net	0	(14)	0	154
Merger-related expenses and deal costs	2,070	4,164	2,955	20,410
Other	263	2,327	6	4,496
Total expenses	(6,800)	(20,854)	(34,159)	(29,065)
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	210,638	167,210	336,533	246,130
Loss from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	0	(562)	(1)	(560)
Income from continuing operations	210,529	166,519	336,314	245,232
Discontinued operations	0	0	0	(10)
Income tax benefit	(109)	(129)	(218)	(338)
Net income	210,529	166,519	336,314	245,222
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	210,529	166,519	336,314	245,222
Ventas, Inc. | Resident Fees and Services
Revenues:
Other revenues	0	0	0	0
Ventas, Inc. | Office Building and Other Services Revenue
Revenues:
Other revenues	0	0	0	0
Ventas Realty
Revenues:
Rental income	35,725	34,299	71,184	68,685
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	0	0	0	0
Interest and other income	51	0	80	0
Total revenues	35,776	34,299	71,264	68,685
Expenses
Interest	82,940	82,644	166,034	164,956
Depreciation and amortization	1,367	1,422	2,755	2,866
Property-level operating expenses	151	82	313	154
Office building services costs	0	0	0	0
General, administrative and professional fees	3,685	4,614	10,153	8,664
Loss on extinguishment of debt, net	4,022	1,787	4,427	12,596
Merger-related expenses and deal costs	0	0	0	0
Other	0	0	1	0
Total expenses	92,165	90,549	183,683	189,236
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	(56,389)	(56,250)	(112,419)	(120,551)
Loss from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	0	0	0	0
Income from continuing operations	(56,389)	(56,250)	(112,419)	(120,551)
Discontinued operations	0	0	0	0
Income tax benefit	0	0	0	0
Net income	(56,389)	(56,250)	(112,419)	(120,551)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(56,389)	(56,250)	(112,419)	(120,551)
Ventas Realty | Resident Fees and Services
Revenues:
Other revenues	0	0	0	0
Ventas Realty | Office Building and Other Services Revenue
Revenues:
Other revenues	0	0	0	0
Ventas Subsidiaries
Revenues:
Rental income	362,577	325,708	728,348	675,530
Income from loans and investments	18,793	56,145	35,496	86,835
Equity earnings in affiliates	(564)	(563)	(1,126)	(1,206)
Interest and other income	9,142	278	9,388	590
Total revenues	913,364	904,846	1,819,487	1,803,108
Expenses
Interest	45,101	58,680	93,297	116,426
Depreciation and amortization	223,360	220,839	456,540	451,201
Property-level operating expenses	435,750	421,331	866,092	834,172
Office building services costs	515	534	1,148	649
General, administrative and professional fees	32,315	32,451	75,275	65,018
Loss on extinguishment of debt, net	0	(1,866)	0	(1,866)
Merger-related expenses and deal costs	2,530	330	3,825	1,420
Other	(11,744)	1,200	(11,465)	2,151
Total expenses	727,827	733,499	1,484,712	1,469,171
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	185,537	171,347	334,775	333,937
Loss from unconsolidated entities	(2,529)	(6,371)	(3,475)	(47,110)
Gain on real estate dispositions	19,150	36,389	24,598	36,435
Income from continuing operations	260,019	202,228	415,125	327,576
Discontinued operations	0	0	0	0
Income tax benefit	57,861	863	59,227	4,314
Net income	260,019	202,228	415,125	327,576
Net income attributable to noncontrolling interests	1,369	2,781	3,172	4,176
Net income attributable to common stockholders	258,650	199,447	411,953	323,400
Ventas Subsidiaries | Resident Fees and Services
Revenues:
Other revenues	520,725	518,989	1,042,172	1,033,742
Ventas Subsidiaries | Office Building and Other Services Revenue
Revenues:
Other revenues	$ 2,691	$ 4,289	$ 5,209	$ 7,617