Acquisitions (Allocation of the Fair Value of Assets Acquired and Liabilities Assumed As Of The Acquisition Date (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Business Acquisition [Line Items]
Land	$ 9,363			$ 7,602
Buildings, improvements and equipment	14,341	$ 445		80,975
Construction in Progress	103,334	114,283		62,884
Other assets				309
Deferred income taxes				6,045
Goodwill	173,843	$ 173,843
Fort Worth Facility
Business Acquisition [Line Items]
Land	136
Buildings, improvements and equipment	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 | Adjustment
Business Acquisition [Line Items]
Construction in Progress	3
Acquired intangibles	(3)
Piscataway Facility
Business Acquisition [Line Items]
Land			$ 7,466
Buildings, improvements and equipment			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
Measurement period adjustment	0
Piscataway Facility | Adjustment
Business Acquisition [Line Items]
Land	26
Buildings, improvements and equipment	1,996
Acquired intangibles	(2,087)
Deferred costs	306
Total identifiable assets acquired	241
Acquired below market lease	241
Total liabilities assumed	$ 241
Preliminary Allocation Reported | Fort Worth Facility
Business Acquisition [Line Items]
Land				136
Buildings, improvements and equipment				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
Preliminary Allocation Reported | Piscataway Facility
Business Acquisition [Line Items]
Land					$ 7,440
Buildings, improvements and equipment					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