STOCKHOLDERS' EQUITY - Capital Stock (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Oct. 28, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Issuance of common stock, shares		18,566,822
Proceeds for the issuance of common stock		$ 1,300.0
Equity offering program, remaining authorized offering amount		252.1
Conversion of stock, value redeemed		$ 23.0
Common Stock
Business Acquisition [Line Items]
Conversion of stock, number of Ventas shares issued		370,558
Ventas Realty OP Units
Business Acquisition [Line Items]
Partners' capital account, units, redeemed (in shares)		65,581
Class C Units
Business Acquisition [Line Items]
Partners' capital account, units, redeemed (in shares)		311,208
Subsequent Event
Business Acquisition [Line Items]
Issuance of common stock, shares	297,019
Proceeds for the issuance of common stock	$ 21.2
Sales agent commissions for common stock sales	$ 0.3