Acquisitions (Allocation of the Fair Value of Assets Acquired and Liabilities Assumed as of the Acquisition Date) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016
Business Acquisition [Line Items]
Land	$ 5,019		$ 7,440
Buildings and improvements			80,390
Construction in Progress	41,994		13,900
Deferred costs			4,391
Other assets			$ 303
Fort Worth Facility
Business Acquisition [Line Items]
Land	136
Buildings and improvements	610
Construction in Progress	48,987
Acquired intangibles	237
Deferred costs	23
Other assets	7
Net working capital	86
Total identifiable assets acquired	50,086
Fort Worth Facility | Original Allocation Reported
Business Acquisition [Line Items]
Land		$ 136
Buildings and improvements		610
Construction in Progress		48,984
Acquired intangibles		240
Deferred costs		23
Other assets		7
Net working capital		86
Total identifiable assets acquired		$ 50,086
Fort Worth Facility | Adjustment
Business Acquisition [Line Items]
Construction in Progress	3
Acquired intangibles	(3)
Piscataway Facility
Business Acquisition [Line Items]
Land				$ 7,466
Buildings and improvements				80,366
Construction in Progress				13,900
Acquired intangibles				19,581
Deferred costs				4,390
Other assets				106
Total identifiable assets acquired				125,809
Acquired below market lease				809
Net working capital				2,019
Total liabilities assumed				2,828
Net identifiable assets acquired				122,981
Piscataway Facility | Original Allocation Reported
Business Acquisition [Line Items]
Land				7,440
Buildings and improvements				78,370
Construction in Progress				13,900
Acquired intangibles				21,668
Deferred costs				4,084
Other assets				106
Total identifiable assets acquired				125,568
Acquired below market lease				568
Net working capital				2,019
Total liabilities assumed				2,587
Net identifiable assets acquired				$ 122,981
Piscataway Facility | Adjustment
Business Acquisition [Line Items]
Land	26
Buildings and improvements	1,996
Acquired intangibles	(2,087)
Deferred costs	306
Total identifiable assets acquired	241
Acquired below market lease	241
Total liabilities assumed	$ 241