CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenues:
Rental income	$ 360,262	$ 399,498	$ 745,071	$ 794,720
Resident fees and services	518,989	460,243	1,033,742	924,431
Office building and other services revenue	4,289	3,179	7,617	6,585
Income from loans and investments	56,417	32,368	87,598	52,514
Equity earnings in affiliates	0	0	0	0
Interest and other income	2,347	202	11,981	683
Total revenues	942,304	895,490	1,886,009	1,778,933
Expenses
Interest	113,029	113,572	224,392	222,376
Depreciation and amortization	223,634	224,108	456,784	441,891
Property-level operating expenses	421,413	365,830	834,326	734,817
Office building services costs	534	552	649	1,290
General, administrative and professional fees	36,656	33,282	73,830	67,243
(Gain) loss on extinguishment of debt, net	(93)	36	10,884	345
Merger-related expenses and deal costs	4,494	6,043	21,830	8,099
Other	3,527	1,848	6,647	3,036
Total expenses	803,194	745,271	1,629,342	1,479,097
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	139,110	150,219	256,667	299,836
Income (loss) from unconsolidated entities	(6,371)	(106)	(47,110)	3,044
Income tax benefit	734	2,159	3,976	5,304
Income from continuing operations	133,473	152,272	213,533	308,184
Discontinued operations	0	(23)	(10)	(76)
Gain on real estate dispositions	35,827	719	35,875	44,008
Net income	169,300	152,968	249,398	352,116	$ 1,361,112
Net income attributable to noncontrolling interests	2,781	1,137	4,176	2,158
Net income attributable to common stockholders	166,519	151,831	245,222	349,958
Consolidated Elimination
Revenues:
Rental income	0	0	0	0
Resident fees and services	0	0	0	0
Office building and other services revenue	0	0	0	0
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	(143,197)	(130,806)	(202,849)	(314,153)
Interest and other income	0	0	0	0
Total revenues	(143,197)	(130,806)	(202,849)	(314,153)
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
(Gain) 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, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(143,197)	(130,806)	(202,849)	(314,153)
Income (loss) from unconsolidated entities	0	0	0	0
Income tax benefit	0	0	0	0
Income from continuing operations	(143,197)	(130,806)	(202,849)	(314,153)
Discontinued operations	0	0	0	0
Gain on real estate dispositions	0	0	0	0
Net income	(143,197)	(130,806)	(202,849)	(314,153)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(143,197)	(130,806)	(202,849)	(314,153)
Ventas, Inc.
Revenues:
Rental income	255	596	856	1,181
Resident fees and services	0	0	0	0
Office building and other services revenue	0	0	0	0
Income from loans and investments	272	319	763	600
Equity earnings in affiliates	143,760	131,210	204,055	314,751
Interest and other income	2,069	28	11,391	371
Total revenues	146,356	132,153	217,065	316,903
Expenses
Interest	(28,295)	(27,732)	(56,990)	(44,367)
Depreciation and amortization	1,373	1,419	2,717	2,827
Property-level operating expenses	0	0	0	0
Office building services costs	0	0	0	0
General, administrative and professional fees	(409)	186	148	313
(Gain) loss on extinguishment of debt, net	(14)	0	154	0
Merger-related expenses and deal costs	4,164	5,783	20,410	7,646
Other	2,327	466	4,496	119
Total expenses	(20,854)	(19,878)	(29,065)	(33,462)
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	167,210	152,031	246,130	350,365
Income (loss) from unconsolidated entities	0	0	0	0
Income tax benefit	(129)	(177)	(338)	(331)
Income from continuing operations	167,081	151,854	245,792	350,034
Discontinued operations	0	(23)	(10)	(76)
Gain on real estate dispositions	(562)	0	(560)	0
Net income	166,519	151,831	245,222	349,958
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	166,519	151,831	245,222	349,958
Ventas Realty
Revenues:
Rental income	34,299	48,451	68,685	96,270
Resident fees and services	0	0	0	0
Office building and other services revenue	0	0	0	0
Income from loans and investments	0	0	0	0
Equity earnings in affiliates	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	34,299	48,451	68,685	96,270
Expenses
Interest	82,644	81,516	164,956	156,306
Depreciation and amortization	1,422	2,239	2,866	4,608
Property-level operating expenses	82	83	154	165
Office building services costs	0	0	0	0
General, administrative and professional fees	4,614	4,630	8,664	9,330
(Gain) loss on extinguishment of debt, net	1,787	418	12,596	438
Merger-related expenses and deal costs	0	0	0	0
Other	0	0	0	0
Total expenses	90,549	88,886	189,236	170,847
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(56,250)	(40,435)	(120,551)	(74,577)
Income (loss) from unconsolidated entities	0	0	0	0
Income tax benefit	0	0	0	0
Income from continuing operations	(56,250)	(40,435)	(120,551)	(74,577)
Discontinued operations	0	0	0	0
Gain on real estate dispositions	0	0	0	14,781
Net income	(56,250)	(40,435)	(120,551)	(59,796)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(56,250)	(40,435)	(120,551)	(59,796)
Ventas Subsidiaries
Revenues:
Rental income	325,708	350,451	675,530	697,269
Resident fees and services	518,989	460,243	1,033,742	924,431
Office building and other services revenue	4,289	3,179	7,617	6,585
Income from loans and investments	56,145	32,049	86,835	51,914
Equity earnings in affiliates	(563)	(404)	(1,206)	(598)
Interest and other income	278	174	590	312
Total revenues	904,846	845,692	1,803,108	1,679,913
Expenses
Interest	58,680	59,788	116,426	110,437
Depreciation and amortization	220,839	220,450	451,201	434,456
Property-level operating expenses	421,331	365,747	834,172	734,652
Office building services costs	534	552	649	1,290
General, administrative and professional fees	32,451	28,466	65,018	57,600
(Gain) loss on extinguishment of debt, net	(1,866)	(382)	(1,866)	(93)
Merger-related expenses and deal costs	330	260	1,420	453
Other	1,200	1,382	2,151	2,917
Total expenses	733,499	676,263	1,469,171	1,341,712
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	171,347	169,429	333,937	338,201
Income (loss) from unconsolidated entities	(6,371)	(106)	(47,110)	3,044
Income tax benefit	863	2,336	4,314	5,635
Income from continuing operations	165,839	171,659	291,141	346,880
Discontinued operations	0	0	0	0
Gain on real estate dispositions	36,389	719	36,435	29,227
Net income	202,228	172,378	327,576	376,107
Net income attributable to noncontrolling interests	2,781	1,137	4,176	2,158
Net income attributable to common stockholders	$ 199,447	$ 171,241	$ 323,400	$ 373,949