Quarterly report pursuant to Section 13 or 15(d)

Notes Payable (Details)

v3.8.0.1
Notes Payable (Details)
$ / shares in Units, $ in Thousands
3 Months Ended
Oct. 15, 2013
USD ($)
Mar. 31, 2018
USD ($)
$ / shares
Oct. 23, 2013
item
Notes Payable      
Class Of Warrant Or Right, Exercise Price Of Warrants Or Rights | $ / shares   $ 0.94  
Sweetwater IDR Bond [Member]      
Notes Payable      
Proceeds from Issuance of Long-term Debt $ 34,000    
Periodic payment amount   $ 18,693  
Due Quarterly Commencing From January 1, 2014 [Member] | Sweetwater IDR Bond [Member]      
Notes Payable      
Fixed interest rate (as a percent)     5.75%
Due Quarterly Commencing From January 1, 2015 [Member] | Sweetwater IDR Bond [Member]      
Notes Payable      
Number of installments | item     28