Other Real Estate Investments - Narrative (Details)		1 Months Ended					3 Months Ended		9 Months Ended
	Oct. 01, 2017 acquisition	Oct. 31, 2017 acquisition	May 31, 2017 USD ($)	Sep. 30, 2016 USD ($) bed	Jul. 31, 2016 USD ($) bed	Dec. 31, 2014 USD ($) a unit	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Real Estate Properties [Line Items]
Preferred equity investment							$ 5,400,000		$ 5,400,000
Proceeds from sale of real estate investment									7,500,000	$ 0
Receipt of preferred return									0	0
Gain on disposition of other real estate investment							0	$ 0	3,538,000	0
Interest income distribution from other real estate investment									1,500,000	0
Preferred Equity Investment
Real Estate Properties [Line Items]
Interest income							200,000	100,000	1,500,000	600,000
Interest income distribution from other real estate investment							$ 0	0	975,000	0
Signature Senior Living
Real Estate Properties [Line Items]
Preferred equity investment						$ 7,500,000
Return from preferred equity investment (percent)						12.00%
Number of units planned for construction | unit						134
Area under construction | a						5
Initial lease yield (percent)						8.00%
Proceeds from sale of real estate investment			$ 7,500,000
Receipt of preferred return			$ 2,500,000
Gain on disposition of other real estate investment									3,500,000
Interest income									1,000,000
Interest income distribution from other real estate investment									$ 500,000
Cascadia Development, LLC
Real Estate Properties [Line Items]
Preferred equity investment				$ 2,300,000	$ 2,200,000			$ 2,300,000		$ 2,300,000
Number of beds planned for construction | bed				99	99
Initial lease yield (percent)				9.00%	9.00%
Preferred equity investment minimum yield				12.00%	12.00%
Cascadia Development, LLC | Prime Rate
Real Estate Properties [Line Items]
Basis spread of preferred equity investment yield				9.50%	9.50%
Subsequent Event
Real Estate Properties [Line Items]
Number of asset acquisitions | acquisition	3	3