Organization - Narrative (Details)								3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) ft² property $ / shares shares	Sep. 02, 2016 shares	Aug. 08, 2016 USD ($) $ / shares	Sep. 30, 2015 shares	Jul. 06, 2015 USD ($) $ / shares shares	Jun. 02, 2015 $ / shares shares	Jun. 30, 2014 $ / shares shares	Sep. 30, 2016 ft² property $ / shares shares	Sep. 30, 2015 shares	Sep. 30, 2016 ft² property $ / shares shares	Sep. 30, 2015 shares	Nov. 08, 2016 ft²	Oct. 31, 2016 $ / shares	Dec. 31, 2015 $ / shares shares	Apr. 08, 2015 $ / shares
Operations [Line Items]
Number of properties (property) | property	326							326		326
Rentable square feet (sqft) | ft²	18,600,000							18,600,000		18,600,000
Occupancy rate	100.00%							100.00%		100.00%
Weighted average remaining lease term (years)										10 years 6 months
Common stock, issued (shares)	170,242,113							170,242,113		170,242,113				168,936,633
Common stock, par value (usd per share) | $ / shares	$ 0.01						$ 0.01	$ 0.01		$ 0.01				$ 0.01	$ 0.01
Common stock issued through distribution reinvestment plan (in shares)							1,100,000
Antidilutive securities (in shares)								9,766,902	11,039,417	9,766,902	11,039,417
Subsequent Event
Operations [Line Items]
Rentable square feet (sqft) | ft²												246,743
Merger Agreement
Operations [Line Items]
Merger Consideration owed to Global II | $	$ 212,600,000
Merger Agreement | Global Trust II
Operations [Line Items]
Common stock, par value (usd per share) | $ / shares			$ 0.01
Potential transaction expenses | $			$ 5,000,000.0
Potential termination fee | $			$ 6,000,000.0
OP Units
Operations [Line Items]
Antidilutive securities (in shares)						1,809,678		545,530	1,809,678	545,530	1,809,678
Conversion of stock (shares)		1,264,148
Class B Units
Operations [Line Items]
Antidilutive securities (in shares)				1,726,323				0	0	0	0
Advisor | OP Units
Operations [Line Items]
Antidilutive securities (in shares)				83,333		1,461,753
Service Provider | OP Units
Operations [Line Items]
Antidilutive securities (in shares)						347,903
Conversion of stock (shares)		347,903
Special Limited Partner | OP Units
Operations [Line Items]
Antidilutive securities (in shares)				22		22
Conversion of stock (shares)		14
Individual Investor | OP Units
Operations [Line Items]
Conversion of stock (shares)		916,231
Common Stock
Operations [Line Items]
Share price (in dollars per share) | $ / shares							$ 10.00
Number of shares offered to be repurchased (shares)						11,900,000
Shares offered to be repurchased (usd per share) | $ / shares					$ 10.5	$ 10.5
Number of shares repurchased during the period (shares)					11,900,000
Value of shares repurchased during the period | $					$ 125,000,000
Common Stock | Merger Agreement
Operations [Line Items]
Conversion ratio			2.27
Common Stock | Merger Agreement | Subsequent Event
Operations [Line Items]
Share price (in dollars per share) | $ / shares													$ 7.41
Common Stock | Class B Units | Merger Agreement
Operations [Line Items]
Conversion ratio			2.27
IPO
Operations [Line Items]
Common stock, issued (shares)							172,300,000
United States
Operations [Line Items]
Percentage of portfolio investments	60.20%							60.20%		60.20%
Europe
Operations [Line Items]
Percentage of portfolio investments	39.80%							39.80%		39.80%