Significant Accounting Policies (Intangibles) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	$ 89,197	$ 89,167
Accumulated amortization	(1,319)	0
Net book value	87,878	89,167
Helium Production Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	55,266	55,266
Accumulated amortization	0	0
Net book value	55,266	55,266
CO2 Purchase Contract [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset value	33,931	33,901
Accumulated amortization	(1,319)	0
Net book value	$ 32,612	$ 33,901