Significant Accounting Policies (Intangibles) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	$ 89,607	$ 89,197
Accumulated amortization	(3,640)	(1,319)
Net book value	85,967us-gaap_FiniteLivedIntangibleAssetsNet	87,878us-gaap_FiniteLivedIntangibleAssetsNet
Helium Production Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	55,266	55,266
Accumulated amortization	(15)	0
Net book value	55,251	55,266
CO2 Purchase Contract [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	34,341	33,931
Accumulated amortization	(3,625)	(1,319)
Net book value	$ 30,716	$ 32,612

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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