CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Revenues:
Rental income	$ 395,222	$ 358,623
Resident fees and services	464,188	463,976
Office building and other services revenue	3,406	7,185
Income from loans and investments	20,146	22,386
Equity earnings in affiliates	0	0
Interest and other income	481	119
Total revenues	883,443	852,289
Expenses
Interest	108,804	103,273
Depreciation and amortization	217,783	236,387
Property-level operating expenses	368,987	356,222
Office building services costs	738	3,451
General, administrative and professional fees	33,961	31,726
(Gain) loss on extinguishment of debt, net	309	314
Merger-related expenses and deal costs	2,056	1,632
Other	1,188	4,168
Total expenses	733,826	737,173
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	149,617	115,116
Income (loss) from unconsolidated entities	3,150	(198)
Income tax benefit	3,145	8,421
Income from continuing operations	155,912	123,339
Discontinued operations	(53)	(489)
Gain on real estate dispositions	43,289	26,184
Net income	199,148	149,034	$ 651,490
Net income attributable to noncontrolling interests	1,021	54
Net income attributable to common stockholders	198,127	148,980
Consolidated Elimination
Revenues:
Rental income	0	0
Resident fees and services	0	0
Office building and other services revenue	0	0
Income from loans and investments	0	0
Equity earnings in affiliates	(136,681)	(108,420)
Interest and other income	0	0
Total revenues	(136,681)	(108,420)
Expenses
Interest	0	0
Depreciation and amortization	0	0
Property-level operating expenses	0	0
Office building services costs	0	0
General, administrative and professional fees	0	0
(Gain) loss on extinguishment of debt, net	0	0
Merger-related expenses and deal costs	0	0
Other	0	0
Total expenses	0	0
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(136,681)	(108,420)
Income (loss) from unconsolidated entities	0	0
Income tax benefit	0	0
Income from continuing operations	(136,681)	(108,420)
Discontinued operations	0	0
Gain on real estate dispositions	0	0
Net income	(136,681)	(108,420)
Net income attributable to noncontrolling interests	0	0
Net income attributable to common stockholders	(136,681)	(108,420)
Ventas, Inc.
Revenues:
Rental income	585	916
Resident fees and services	0	0
Office building and other services revenue	0	602
Income from loans and investments	281	0
Equity earnings in affiliates	136,989	108,762
Interest and other income	343	29
Total revenues	138,198	110,309
Expenses
Interest	(16,600)	(10,795)
Depreciation and amortization	1,409	4,932
Property-level operating expenses	0	0
Office building services costs	0	0
General, administrative and professional fees	130	(15)
(Gain) loss on extinguishment of debt, net	0	0
Merger-related expenses and deal costs	1,863	1,372
Other	(349)	(49)
Total expenses	(13,547)	(4,555)
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	151,745	114,864
Income (loss) from unconsolidated entities	0	0
Income tax benefit	3,145	8,421
Income from continuing operations	154,890	123,285
Discontinued operations	(53)	(489)
Gain on real estate dispositions	43,290	26,184
Net income	198,127	148,980
Net income attributable to noncontrolling interests	0	0
Net income attributable to common stockholders	198,127	148,980
Ventas Realty
Revenues:
Rental income	47,819	48,725
Resident fees and services	0	0
Office building and other services revenue	0	0
Income from loans and investments	0	0
Equity earnings in affiliates	0	0
Interest and other income	0	0
Total revenues	47,819	48,725
Expenses
Interest	74,789	68,579
Depreciation and amortization	2,371	9,914
Property-level operating expenses	83	79
Office building services costs	0	0
General, administrative and professional fees	4,700	4,504
(Gain) loss on extinguishment of debt, net	19	0
Merger-related expenses and deal costs	0
Other	0	0
Total expenses	81,962	83,076
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	(34,143)	(34,351)
Income (loss) from unconsolidated entities	3,321	103
Income tax benefit	0	0
Income from continuing operations	(30,822)	(34,248)
Discontinued operations	0	0
Gain on real estate dispositions	0	0
Net income	(30,822)	(34,248)
Net income attributable to noncontrolling interests	0	0
Net income attributable to common stockholders	(30,822)	(34,248)
Ventas Subsidiaries
Revenues:
Rental income	346,818	308,982
Resident fees and services	464,188	463,976
Office building and other services revenue	3,406	6,583
Income from loans and investments	19,865	22,386
Equity earnings in affiliates	(308)	(342)
Interest and other income	138	90
Total revenues	834,107	801,675
Expenses
Interest	50,615	45,489
Depreciation and amortization	214,003	221,541
Property-level operating expenses	368,904	356,143
Office building services costs	738	3,451
General, administrative and professional fees	29,131	27,237
(Gain) loss on extinguishment of debt, net	290	314
Merger-related expenses and deal costs	193	260
Other	1,537	4,217
Total expenses	665,411	658,652
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests	168,696	143,023
Income (loss) from unconsolidated entities	(171)	(301)
Income tax benefit	0	0
Income from continuing operations	168,525	142,722
Discontinued operations	0	0
Gain on real estate dispositions	(1)	0
Net income	168,524	142,722
Net income attributable to noncontrolling interests	1,021	54
Net income attributable to common stockholders	$ 167,503	$ 142,668