CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Revenues:
Rental income	$ 401,876	$ 368,697	$ 1,196,596	$ 1,081,526
Resident fees and services	461,700	461,974	1,386,131	1,390,387
Office building and other services revenue	3,196	4,317	9,781	17,006
Income from loans and investments	32,985	31,566	85,499	78,098
Equity earnings in affiliates	0	0	0	0
Interest and other income	171	562	854	792
Total revenues	899,928	867,116	2,678,861	2,567,809
Expenses
Interest	113,869	105,063	336,245	312,001
Depreciation and amortization	213,407	208,387	655,298	666,735
Property-level operating expenses	376,207	361,117	1,111,024	1,069,294
Office building services costs	418	974	1,708	6,277
General, administrative and professional fees	33,317	31,567	100,560	95,387
Loss on extinguishment of debt, net	511	383	856	3,165
Merger-related expenses and deal costs	804	16,217	8,903	25,073
Other	13,030	2,430	16,066	8,901
Total expenses	751,563	726,138	2,230,660	2,186,833
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	148,365	140,978	448,201	380,976
Income (loss) from unconsolidated entities	750	931	3,794	2,151
Income tax benefit	7,815	8,537	13,119	28,507
Income from continuing operations	156,930	150,446	465,114	411,634
Discontinued operations	(19)	(118)	(95)	(755)
Gain (loss) on real estate dispositions	458,280	(144)	502,288	31,779
Net income	615,191	150,184	967,307	442,658	$ 651,490
Net income attributable to noncontrolling interests	1,233	732	3,391	1,064
Net income attributable to common stockholders	613,958	149,452	963,916	441,594
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	(133,159)	(143,501)	(397,632)	(375,657)
Interest and other income	0	0	0	0
Total revenues	(133,159)	(143,501)	(397,632)	(375,657)
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, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(133,159)	(143,501)	(397,632)	(375,657)
Income (loss) from unconsolidated entities	0	0	0	0
Income tax benefit	0	0	0	0
Income from continuing operations	(133,159)	(143,501)	(397,632)	(375,657)
Discontinued operations	0	0	0	0
Gain (loss) on real estate dispositions	0	0	0	0
Net income	(133,159)	(143,501)	(397,632)	(375,657)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(133,159)	(143,501)	(397,632)	(375,657)
Ventas, Inc.
Revenues:
Rental income	602	585	1,782	2,084
Resident fees and services	0	0	0	0
Office building and other services revenue	0	401	0	1,605
Income from loans and investments	309	82	908	82
Equity earnings in affiliates	133,571	143,782	398,757	376,570
Interest and other income	3	476	374	546
Total revenues	134,485	145,326	401,821	380,887
Expenses
Interest	(16,801)	(11,779)	(61,095)	(33,668)
Depreciation and amortization	1,314	1,414	4,140	7,549
Property-level operating expenses	0	0	0	0
Office building services costs	0	0	0	0
General, administrative and professional fees	103	(1,359)	421	872
Loss on extinguishment of debt, net	0	(58)	0	0
Merger-related expenses and deal costs	361	15,952	8,007	24,067
Other	1,626	(21)	1,744	4
Total expenses	(13,397)	4,149	(46,783)	(1,176)
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	147,882	141,177	448,604	382,063
Income (loss) from unconsolidated entities	0	0	0	0
Income tax benefit	7,815	8,537	13,119	28,507
Income from continuing operations	155,697	149,714	461,723	410,570
Discontinued operations	(19)	(118)	(95)	(755)
Gain (loss) on real estate dispositions	458,280	(144)	502,288	31,779
Net income	613,958	149,452	963,916	441,594
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	613,958	149,452	963,916	441,594
Ventas Realty
Revenues:
Rental income	45,446	49,652	141,717	147,795
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	45,446	49,652	141,717	147,795
Expenses
Interest	82,007	70,371	238,312	207,961
Depreciation and amortization	1,455	2,833	6,062	15,614
Property-level operating expenses	69	80	235	236
Office building services costs	0	0	0	0
General, administrative and professional fees	4,240	4,940	13,570	13,657
Loss on extinguishment of debt, net	504	340	942	2,772
Merger-related expenses and deal costs	0	0	0	0
Other	0	4	0	8
Total expenses	88,275	78,568	259,121	240,248
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(42,829)	(28,916)	(117,404)	(92,453)
Income (loss) from unconsolidated entities	1,614	783	4,919	1,230
Income tax benefit	0	0	0	0
Income from continuing operations	(41,215)	(28,133)	(112,485)	(91,223)
Discontinued operations	0	0	0	0
Gain (loss) on real estate dispositions	0	0	0	0
Net income	(41,215)	(28,133)	(112,485)	(91,223)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to common stockholders	(41,215)	(28,133)	(112,485)	(91,223)
Ventas Subsidiaries
Revenues:
Rental income	355,828	318,460	1,053,097	931,647
Resident fees and services	461,700	461,974	1,386,131	1,390,387
Office building and other services revenue	3,196	3,916	9,781	15,401
Income from loans and investments	32,676	31,484	84,591	78,016
Equity earnings in affiliates	(412)	(281)	(1,125)	(913)
Interest and other income	168	86	480	246
Total revenues	853,156	815,639	2,532,955	2,414,784
Expenses
Interest	48,663	46,471	159,028	137,708
Depreciation and amortization	210,638	204,140	645,096	643,572
Property-level operating expenses	376,138	361,037	1,110,789	1,069,058
Office building services costs	418	974	1,708	6,277
General, administrative and professional fees	28,974	27,986	86,569	80,858
Loss on extinguishment of debt, net	7	101	(86)	393
Merger-related expenses and deal costs	443	265	896	1,006
Other	11,404	2,447	14,322	8,889
Total expenses	676,685	643,421	2,018,322	1,947,761
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	176,471	172,218	514,633	467,023
Income (loss) from unconsolidated entities	(864)	148	(1,125)	921
Income tax benefit	0	0	0	0
Income from continuing operations	175,607	172,366	513,508	467,944
Discontinued operations	0	0	0	0
Gain (loss) on real estate dispositions	0	0	0	0
Net income	175,607	172,366	513,508	467,944
Net income attributable to noncontrolling interests	1,233	732	3,391	1,064
Net income attributable to common stockholders	$ 174,374	$ 171,634	$ 510,117	$ 466,880