Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) item	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Information.
Number of segments | item	2
Rental income	$ 63,611	$ 62,659
Expenses:
Real estate taxes	7,653	7,410
Utility expenses	4,174	4,571
Other operating expenses	12,911	12,210
Depreciation and amortization	18,324	17,215
Acquisition related costs	152	6
General and administrative	3,526	4,004
Total expenses	46,740	45,416
Operating income (loss)	16,871	17,243
Interest income	6	12
Interest expense	(9,364)	(9,302)
Gain on early extinguishment of debt	104
Loss on issuance of shares by Select Income REIT		(40,771)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of investees	7,617	(32,818)
Income tax expense	(15)	(30)
Equity in earnings (losses) of investees	9,934	(316)
Income (loss) from continuing operations	17,536	(33,164)
Loss from discontinued operations	(149)	(206)
Net income (loss)	17,387	(33,370)
Total assets	2,259,395		$ 2,168,510
Operating Segments | Investment in Real Estate
Segment Information.
Rental income	63,611	62,659
Expenses:
Real estate taxes	7,653	7,410
Utility expenses	4,174	4,571
Other operating expenses	12,911	12,210
Depreciation and amortization	18,324	17,215
Acquisition related costs	152	6
Total expenses	43,214	41,412
Operating income (loss)	20,397	21,247
Interest expense	(8,269)	(2,267)
Gain on early extinguishment of debt	104
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of investees	12,232	18,980
Income (loss) from continuing operations	12,232	18,980
Loss from discontinued operations	(149)	(206)
Net income (loss)	12,083	18,774
Total assets	1,708,910		1,639,462
Operating Segments | Investment in SIR
Expenses:
Loss on issuance of shares by Select Income REIT		(40,771)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of investees		(40,771)
Equity in earnings (losses) of investees	9,857	(388)
Income (loss) from continuing operations	9,857	(41,159)
Net income (loss)	9,857	(41,159)
Total assets	493,259		491,369
Corporate, Non-Segment
Expenses:
General and administrative	3,526	4,004
Total expenses	3,526	4,004
Operating income (loss)	(3,526)	(4,004)
Interest income	6	12
Interest expense	(1,095)	(7,035)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of investees	(4,615)	(11,027)
Income tax expense	(15)	(30)
Equity in earnings (losses) of investees	77	72
Income (loss) from continuing operations	(4,553)	(10,985)
Net income (loss)	(4,553)	$ (10,985)
Total assets	$ 57,226		$ 37,679