Contingencies and litigations (Details) (USD $)	Dec. 31, 2012	Apr. 30, 2012	Feb. 14, 2012	Mar. 31, 2011	Dec. 31, 2009	Jan. 31, 2006
Acutal damages found by jury in millions					66.5
Actual damages in tortous interference claim millions					31.16
Exemplary damages and individual and Eurenergy millions					8.5
reinstated the jury award of actual damages jointly and severely against The individual and EurEnergy millions			66.5
received an invoice from Chesapeake						$ 556,217
Chesapeake received a summary judgment award				686,874
Recorded a liability due Chesapeake	491,000
Company attempted to acquire Sterling and invested a total of approximately					400,000
Investment in Sterling written off					50,000
Settlement with Sterling and payment		$ 112,500