Derivative Instruments (Textual) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments [Abstract]
Cash flow hedge gain loss to be reclassified within twelve months	$ 914
Derivative cash received on hedge	$ 52,719	$ 108,347

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

No definition available.

Name:	well_Cashflowhedgegainlosstobereclassifiedwithintwelvemonths2
Namespace Prefix:	well_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration