Fair Value of Contingent Purchase Price Consideration (Parenthetical) (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($) ft²	Dec. 31, 2012 USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Contingent purchase price consideration									$ 4,644	$ 7,500	$ 268
Operating income (loss)	$ 5,764	$ 3,660	$ 2,714	$ (991)	$ (4,824)	$ (7,925)	$ (3,650)	$ (7,909)	11,147	(24,308)	(23,178)
Superior Residences of Panama City
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Additional purchase price consideration									$ 4,000
Additional purchase price consideration period									36 months
The Shores of Lake Phalen
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Additional purchase price consideration									$ 800
Additional purchase price consideration period									12 months
Siena Pavilion VI
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Additional purchase price consideration									$ 3,300
Additional purchase price consideration period									6 months
Additional tenant improvements consideration									$ 500
Center One
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Contingent purchase price consideration									$ 2,800
Contingent consideration arrangements, description									The purchase price be placed in an escrow account as the seller provided a rent guarantee to the Company in connection with two seller leased spaces at the property for a term equal to the earlier of five years or at such time as a suitable replacement tenant can be found (“Center One Rent Guarantee”).
Capital Health
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Contingent purchase price consideration													$ 7,000
Capital Health | Yield Guarantee
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Operating income (loss)										7,100	$ 7,000	$ 6,900
Received purchase consideration										$ 7,000
Medical Portfolio I
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Contingent consideration arrangements, description												The Chestnut Commons Earn-Out fee was equal to (a) the base rent due for the first full year of the lease applicable to the expansion space divided by 8% minus (b) the costs incurred by the Company in connection with the exercise by Cleveland Clinic of its option for the expansion space, including tenant improvement costs, multiplied by 50%.
Expandable lease space under earn-out agreement | ft²												10,000
Earn out expiration date												2015-08