CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Rental income	$ 408,322	$ 384,028	$ 1,208,388	$ 1,129,099
Income from loans and investments	30,164	18,108	66,819	105,706
Equity earnings in affiliates	0	0	0	0
Interest and other income	620	12,554	10,109	24,535
Total revenues	983,155	936,538	2,876,746	2,822,547
Expenses
Interest	113,967	107,581	334,955	331,973
Depreciation and amortization	234,603	218,579	696,710	675,363
Property-level operating expenses	461,493	428,389	1,327,898	1,262,715
Office building services costs	627	431	1,775	1,080
General, administrative and professional fees	40,530	39,677	124,369	113,507
Loss on extinguishment of debt, net	37,434	39,527	41,861	50,411
Merger-related expenses and deal costs	4,304	4,458	11,084	26,288
Other	(2,164)	(1,244)	9,294	(7,891)
Total expenses	895,122	839,886	2,529,358	2,469,228
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	88,033	96,652	347,388	353,319
Income (loss) from unconsolidated entities	854	(716)	(2,621)	(47,826)
Gain on real estate dispositions	36	18	24,633	35,893
Income from continuing operations	86,918	103,281	426,404	352,689
Discontinued operations	0	0	0	(10)
Income tax (expense) benefit	(2,005)	7,327	57,004	11,303
Net income	86,918	103,281	426,404	352,679
Net income attributable to noncontrolling interests	1,659	1,309	4,831	5,485
Net income attributable to common stockholders	85,259	101,972	421,573	347,194
Resident Fees and Services
Revenues:
Other revenues	541,090	518,560	1,583,262	1,552,302
Office Building and Other Services Revenue
Revenues:
Other revenues	2,959	3,288	8,168	10,905
Consolidated Elimination
Revenues:
Rental income	0	0	0	0
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	(68,650)	(73,174)	(368,184)	(276,025)
Interest and other income	0	0	0	0
Total revenues	(68,650)	(73,174)	(368,184)	(276,025)
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	(68,650)	(73,174)	(368,184)	(276,025)
Income (loss) from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	0	0	0	0
Income from continuing operations	(68,650)	(73,174)	(368,184)	(276,025)
Discontinued operations	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Net income	(68,650)	(73,174)	(368,184)	(276,025)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(68,650)	(73,174)	(368,184)	(276,025)
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	270	275	804	1,132
Income from loans and investments	817	387	1,975	1,150
Equity earnings in affiliates	69,503	74,048	370,164	278,103
Interest and other income	141	12,335	162	23,726
Total revenues	70,731	87,045	373,105	304,111
Expenses
Interest	(25,929)	(19,307)	(64,272)	(76,297)
Depreciation and amortization	1,429	1,365	4,241	4,081
Property-level operating expenses	0	0	0	0
Office building services costs	0	0	0	0
General, administrative and professional fees	6,174	2,744	4,586	2,892
Loss on extinguishment of debt, net	0	202	0	356
Merger-related expenses and deal costs	1,974	2,980	4,929	23,390
Other	(1,030)	(28)	(1,036)	(4,524)
Total expenses	(15,322)	(11,988)	(49,480)	(41,054)
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	86,053	99,033	422,585	345,165
Income (loss) from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	0	(5)	0	(567)
Income from continuing operations	85,259	101,972	421,573	347,204
Discontinued operations	0	0	0	(10)
Income tax (expense) benefit	(794)	2,944	(1,012)	2,606
Net income	85,259	101,972	421,573	347,194
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	85,259	101,972	421,573	347,194
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	35,852	35,189	107,036	103,874
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	0	0	0	0
Interest and other income	64	8	144	8
Total revenues	35,916	35,197	107,180	103,882
Expenses
Interest	79,156	80,255	245,189	245,210
Depreciation and amortization	1,328	1,411	4,083	4,277
Property-level operating expenses	136	77	449	231
Office building services costs	0	0	0	0
General, administrative and professional fees	3,433	4,477	13,586	13,142
Loss on extinguishment of debt, net	37,434	36,219	41,862	48,815
Merger-related expenses and deal costs	0	0	0	0
Other	(2)	(25)	(2)	(25)
Total expenses	121,489	122,464	305,171	311,700
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	(85,573)	(87,267)	(197,991)	(207,818)
Income (loss) from unconsolidated entities	0	0	0	0
Gain on real estate dispositions	88	0	88	0
Income from continuing operations	(85,485)	(87,267)	(197,903)	(207,818)
Discontinued operations	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Net income	(85,485)	(87,267)	(197,903)	(207,818)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(85,485)	(87,267)	(197,903)	(207,818)
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	372,200	348,564	1,100,548	1,024,093
Income from loans and investments	29,347	17,721	64,844	104,556
Equity earnings in affiliates	(853)	(874)	(1,980)	(2,078)
Interest and other income	415	211	9,803	801
Total revenues	945,158	887,470	2,764,645	2,690,579
Expenses
Interest	60,740	46,633	154,038	163,060
Depreciation and amortization	231,846	215,803	688,386	667,005
Property-level operating expenses	461,357	428,312	1,327,449	1,262,484
Office building services costs	627	431	1,775	1,080
General, administrative and professional fees	30,923	32,456	106,197	97,473
Loss on extinguishment of debt, net	0	3,106	(1)	1,240
Merger-related expenses and deal costs	2,330	1,478	6,155	2,898
Other	(1,132)	(1,191)	10,332	(3,342)
Total expenses	788,955	729,410	2,273,667	2,198,582
Income before unconsolidated entities, real estate dispositions, income taxes, discontinued operations and noncontrolling interests	156,203	158,060	490,978	491,997
Income (loss) from unconsolidated entities	854	(716)	(2,621)	(47,826)
Gain on real estate dispositions	(52)	23	24,545	36,460
Income from continuing operations	155,794	161,750	570,918	489,328
Discontinued operations	0	0	0	0
Income tax (expense) benefit	(1,211)	4,383	58,016	8,697
Net income	155,794	161,750	570,918	489,328
Net income attributable to noncontrolling interests	1,659	1,309	4,831	5,485
Net income attributable to common stockholders	154,135	160,441	566,087	483,843
Ventas Subsidiaries | Resident Fees and Services
Revenues:
Other revenues	541,090	518,560	1,583,262	1,552,302
Ventas Subsidiaries | Office Building and Other Services Revenue
Revenues:
Other revenues	$ 2,959	$ 3,288	$ 8,168	$ 10,905