CONDENSED CONSOLIDATING INFORMATION (Unaudited) - Statement of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Condensed Consolidating Statement of Cash Flows
Net cash (used in) provided by operating activities	$ 710,336	$ 723,401
Cash flows from investing activities:
Net investment in real estate property	(12,257)	(324,492)
Investment in loans receivable and other	(211,554)	(718,233)
Proceeds from real estate disposals	312,243	104,570
Proceeds from loans receivable	866,097	25,067
Development project expenditures	(155,682)	(143,269)
Capital expenditures	(42,029)	(55,952)
Distributions from unconsolidated entities	6,792	0
Investment in unconsolidated entities	(40,033)	(39,048)
Insurance proceeds for property damage claims	2,329	1,393
Net cash provided by (used in) investing activities	725,906	(1,149,964)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	(197,726)	364,456
Proceeds from debt	750,316	1,028,509
Repayment of debt	(1,431,887)	(656,536)
Purchase of noncontrolling interests	(2,429)	(15,809)
Net change in intercompany debt	0	0
Payment of deferred financing costs	(6,348)	(19,687)
Issuance of common stock, net	0	73,596
Cash distribution from (to) affiliates	0	0
Cash distribution to common stockholders	(563,395)	(550,965)
Cash distribution to redeemable OP Unitholders	(3,744)	(3,720)
Contributions from noncontrolling interests	0	2,227
Cash issued for redemption of OP and Class C Units	(975)	0
Distributions to noncontrolling interests	(7,808)	(4,156)
Other	(1,995)	9,702
Net cash (used in) provided by financing activities	(1,465,991)	227,617
Net decrease in cash, cash equivalents and restricted cash	(29,749)	(198,946)
Effect of foreign currency translation	(401)	3,288
Cash, cash equivalents and restricted cash at beginning of period	188,253	367,354
Cash, cash equivalents and restricted cash at end of period	158,103	171,696
Consolidated Elimination
Condensed Consolidating Statement of Cash Flows
Net cash (used in) provided by operating activities	0	0
Cash flows from investing activities:
Net investment in real estate property	0	0
Investment in loans receivable and other	0	0
Proceeds from real estate disposals	0	0
Proceeds from loans receivable	0	0
Development project expenditures	0	0
Capital expenditures	0	0
Distributions from unconsolidated entities	0
Investment in unconsolidated entities	0	0
Insurance proceeds for property damage claims	0	0
Net cash provided by (used in) investing activities	0	0
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	0	0
Proceeds from debt	0	0
Repayment of debt	0	0
Purchase of noncontrolling interests	0	0
Net change in intercompany debt	0	0
Payment of deferred financing costs	0	0
Issuance of common stock, net		0
Cash distribution from (to) affiliates	0	0
Cash distribution to common stockholders	0	0
Cash distribution to redeemable OP Unitholders	0	0
Contributions from noncontrolling interests		0
Cash issued for redemption of OP and Class C Units	0
Distributions to noncontrolling interests	0	0
Other	0	0
Net cash (used in) provided by financing activities	0	0
Net decrease in cash, cash equivalents and restricted cash	0	0
Effect of foreign currency translation	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	0	0
Ventas, Inc.
Condensed Consolidating Statement of Cash Flows
Net cash (used in) provided by operating activities	(3,651)	41,315
Cash flows from investing activities:
Net investment in real estate property	(12,257)	(295,114)
Investment in loans receivable and other	(2,830)	(2,575)
Proceeds from real estate disposals	312,243	104,570
Proceeds from loans receivable	1,452	21
Development project expenditures	0	0
Capital expenditures	0	0
Distributions from unconsolidated entities	6,792
Investment in unconsolidated entities	0	0
Insurance proceeds for property damage claims	0	0
Net cash provided by (used in) investing activities	305,400	(193,098)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	0	0
Proceeds from debt	0	0
Repayment of debt	0	0
Purchase of noncontrolling interests	(2,429)	(15,809)
Net change in intercompany debt	237,376	795,816
Payment of deferred financing costs	0	0
Issuance of common stock, net		73,596
Cash distribution from (to) affiliates	7,358	(370,552)
Cash distribution to common stockholders	(563,395)	(550,965)
Cash distribution to redeemable OP Unitholders	0	0
Contributions from noncontrolling interests		0
Cash issued for redemption of OP and Class C Units	0
Distributions to noncontrolling interests	0	0
Other	(1,995)	9,702
Net cash (used in) provided by financing activities	(323,085)	(58,212)
Net decrease in cash, cash equivalents and restricted cash	(21,336)	(209,995)
Effect of foreign currency translation	(7,744)	16,529
Cash, cash equivalents and restricted cash at beginning of period	46,945	207,789
Cash, cash equivalents and restricted cash at end of period	17,865	14,323
Ventas Realty
Condensed Consolidating Statement of Cash Flows
Net cash (used in) provided by operating activities	(107,438)	(46,928)
Cash flows from investing activities:
Net investment in real estate property	0	0
Investment in loans receivable and other	0	0
Proceeds from real estate disposals	0	0
Proceeds from loans receivable	0	0
Development project expenditures	0	0
Capital expenditures	0	(15)
Distributions from unconsolidated entities	0
Investment in unconsolidated entities	0	0
Insurance proceeds for property damage claims	0	0
Net cash provided by (used in) investing activities	0	(15)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	(192,531)	453,000
Proceeds from debt	655,044	793,904
Repayment of debt	(1,311,098)	(300,019)
Purchase of noncontrolling interests	0	0
Net change in intercompany debt	961,644	(892,894)
Payment of deferred financing costs	(5,621)	(18,262)
Issuance of common stock, net		0
Cash distribution from (to) affiliates	0	11,291
Cash distribution to common stockholders	0	0
Cash distribution to redeemable OP Unitholders	0	0
Contributions from noncontrolling interests		0
Cash issued for redemption of OP and Class C Units	0
Distributions to noncontrolling interests	0	0
Other	0	0
Net cash (used in) provided by financing activities	107,438	47,020
Net decrease in cash, cash equivalents and restricted cash	0	77
Effect of foreign currency translation	0	0
Cash, cash equivalents and restricted cash at beginning of period	128	1,504
Cash, cash equivalents and restricted cash at end of period	128	1,581
Ventas Subsidiaries
Condensed Consolidating Statement of Cash Flows
Net cash (used in) provided by operating activities	821,425	729,014
Cash flows from investing activities:
Net investment in real estate property	0	(29,378)
Investment in loans receivable and other	(208,724)	(715,658)
Proceeds from real estate disposals	0	0
Proceeds from loans receivable	864,645	25,046
Development project expenditures	(155,682)	(143,269)
Capital expenditures	(42,029)	(55,937)
Distributions from unconsolidated entities	0
Investment in unconsolidated entities	(40,033)	(39,048)
Insurance proceeds for property damage claims	2,329	1,393
Net cash provided by (used in) investing activities	420,506	(956,851)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	(5,195)	(88,544)
Proceeds from debt	95,272	234,605
Repayment of debt	(120,789)	(356,517)
Purchase of noncontrolling interests	0	0
Net change in intercompany debt	(1,199,020)	97,078
Payment of deferred financing costs	(727)	(1,425)
Issuance of common stock, net		0
Cash distribution from (to) affiliates	(7,358)	359,261
Cash distribution to common stockholders	0	0
Cash distribution to redeemable OP Unitholders	(3,744)	(3,720)
Contributions from noncontrolling interests		2,227
Cash issued for redemption of OP and Class C Units	(975)
Distributions to noncontrolling interests	(7,808)	(4,156)
Other	0	0
Net cash (used in) provided by financing activities	(1,250,344)	238,809
Net decrease in cash, cash equivalents and restricted cash	(8,413)	10,972
Effect of foreign currency translation	7,343	(13,241)
Cash, cash equivalents and restricted cash at beginning of period	141,180	158,061
Cash, cash equivalents and restricted cash at end of period	$ 140,110	$ 155,792