SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended								11 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, 2014	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 loan	Dec. 31, 2016 number_mortgage_loans_impaired	Dec. 31, 2015 loan	Dec. 31, 2015 number_mortgage_loans_impaired
Basis of accounting and principles of combination and consolidation
Maximum cash amount insured at several financial institutions					$ 250,000						$ 250,000		$ 250,000
Number of originated loans impaired														0	0	0	0
Expected term for completion of real estate disposals										1 year
Unamortized debt issuance costs													4,025,000
Percentage of applicable cash saving in income tax distributable to specified unitholders									85.00%	85.00%
Percentage of applicable cash saving in income tax available for the entity									15.00%	15.00%
Percentage of commercial mortgage backed securities rated below AA	2.60%									2.60%
Additional deferred financing cost amortization										$ 7,459,000	5,757,000	$ 5,802,000
Income tax expense (benefit)	$ 773,000	$ 8,721,000	$ (2,301,000)	$ (873,000)	10,457,000	$ (4,181,000)	$ 5,177,000	$ 3,104,000		6,320,000	14,557,000	26,605,000
Additional return on equity from Company's investments										1,017,000	294,000	1,957,000
Depreciation and amortization										$ 39,447,000	39,061,000	$ 28,447,000
Out-of-Period Adjustment
Basis of accounting and principles of combination and consolidation
Additional deferred financing cost amortization				500,000
Depreciation and amortization	1,200,000
Out-of-Period Adjustment | Noncontrolling Interest in Consolidated Joint Ventures
Basis of accounting and principles of combination and consolidation
Additional return on equity from Company's investments				900,000
Out-of-Period Adjustment | Tax Year 2015 | State and Local Jurisdiction
Basis of accounting and principles of combination and consolidation
Income tax expense (benefit)				$ 1,200,000
Out-of-Period Adjustment Related to Prior Years
Basis of accounting and principles of combination and consolidation
Depreciation and amortization	$ 600,000
Senior Unsecured Notes | Various Dates
Basis of accounting and principles of combination and consolidation
Unamortized debt issuance costs					6,900,000						6,900,000		4,000,000.0
Building | Minimum
Basis of accounting and principles of combination and consolidation
Estimated useful lives of real estate										20 years
Building | Maximum
Basis of accounting and principles of combination and consolidation
Estimated useful lives of real estate										47 years
Building Fixtures and Improvements | Minimum
Basis of accounting and principles of combination and consolidation
Estimated useful lives of real estate										4 years
Building Fixtures and Improvements | Maximum
Basis of accounting and principles of combination and consolidation
Estimated useful lives of real estate										15 years
Other Assets
Basis of accounting and principles of combination and consolidation
Tenant security deposits					$ 19,000,000.0						$ 19,000,000.0		$ 24,900,000