Equity Investment in Select Income REIT - Income Statement Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 69,296	$ 63,611
Real estate taxes	8,177	7,653
Other operating expenses	13,992	12,911
Depreciation and amortization	20,505	18,324
Acquisition related costs	0	152
General and administrative	3,962	3,526
Total expenses	51,242	46,740
Operating income	18,054	16,871
Dividend income	304	0
Interest expense	(13,581)	(9,364)
Income from continuing operations before income taxes and equity in earnings of investees	4,838	7,617
Income tax expense	(18)	(15)
Equity in earnings of investees	$ 2,739	$ 9,934
Weighted average common shares outstanding (basic) (in shares)	71,079	71,031
Weighted average common shares outstanding (diluted) (in shares)	71,094	71,031
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0.10	$ 0.24
SIR
Schedule of Equity Method Investments [Line Items]
Equity in earnings of investees	$ 2,611	$ 9,857
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Rental income	97,344	97,860
Tenant reimbursements and other income	18,950	19,372
Total revenues	116,294	117,232
Real estate taxes	10,843	10,288
Other operating expenses	12,867	12,958
Depreciation and amortization	33,740	33,469
Acquisition related costs	0	58
General and administrative	14,888	6,976
Reserve for straight line rent receivable, net	12,517	0
Loss on asset impairment	4,047	0
Total expenses	88,902	63,749
Operating income	27,392	53,483
Dividend income	397	0
Interest expense	(21,087)	(20,609)
Income from continuing operations before income taxes and equity in earnings of investees	6,702	32,874
Income tax expense	(102)	(139)
Equity in earnings of investees	128	77
Net income	6,728	32,812
Net income allocated to noncontrolling interest	0	(33)
Net income attributed to SIR	$ 6,728	$ 32,779
Weighted average common shares outstanding (basic) (in shares)	89,331	89,286
Weighted average common shares outstanding (diluted) (in shares)	89,348	89,295
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0.08	$ 0.37