Real Estate Properties - Summary of Properties Sold (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2013 building property	Dec. 31, 2016 USD ($) building	Dec. 31, 2015 USD ($) building	Dec. 31, 2014 USD ($) ft² building property	Mar. 31, 2014 ft²
Real Estate Properties [Line Items]
Number of Properties | property	3
Number of Buildings | building	18
Square Footage | ft²					5,641,450
Loss (gain) on asset impairment from discontinued operations		$ 0	$ 0	$ 2,238
Gain (loss) on early extinguishment of debt from discontinued operations		$ 0	$ 0	$ 3,345
Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property				14
Number of Buildings | building		62	135	43
Square Footage | ft²				2,784,098
Sales Price		$ 1,259,895	$ 1,999,413	$ 215,900
Loss (gain) on asset impairment from discontinued operations				2,200
Gain (loss) on early extinguishment of debt from discontinued operations				$ (3,300)