Acquisition of Real Estate (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014 sqft acre
Business Acquisition [Line Items]
Cash consideration paid for acquisition	$ 73,399,000	$ 59,165,000
Princeton Facility [Member]
Business Acquisition [Line Items]
Aggregate costs related to acquisition			$ 73,300,000
Acres of real estate property			194
Area of facility			560,000
Lease period	10 years
Renewal of lease period	15 years
Princeton Facility [Member] | Raised Floor With Twelve MW Gross Power [Member]
Business Acquisition [Line Items]
Area of facility			58,000
Capacity of the plant			12