Subsequent Events - Narrative (Details) $ in Thousands	1 Months Ended		6 Months Ended	12 Months Ended
	Jul. 31, 2016 USD ($) ft² building property	Jan. 31, 2013 building	Jun. 30, 2016 USD ($) ft² building	Dec. 31, 2015 USD ($) ft² building property
Subsequent Event [Line Items]
Number of buildings sold		18
Disposed of by Sale
Subsequent Event [Line Items]
Number of properties sold | property				91
Number of buildings sold			31	135
Property square feet | ft²			2,039,997	18,900,000
Gross sales price | $			$ 413,765	$ 2,000,000
Subsequent event | Disposed of by Sale
Subsequent Event [Line Items]
Number of properties sold | property	4
Number of buildings sold	4
Property square feet | ft²	1,369,902
Gross sales price | $	$ 265,000
Sky Park Centre San Diego CA | Subsequent event | Disposed of by Sale
Subsequent Event [Line Items]
Number of buildings sold	2
Property square feet | ft²	63,485
Gross sales price | $	$ 13,700
Raintree Industrial Park | Subsequent event | Disposed of by Sale
Subsequent Event [Line Items]
Number of buildings sold	12
Property square feet | ft²	563,182
Gross sales price | $	$ 11,500