Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Amortizable Intangible Assets (Details)

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Summary of Significant Accounting Policies - Amortizable Intangible Assets (Details) - USD ($)
 3 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]        
Impairment of finite lived intangible assets     $ 0 $ 0
Impairment of intangible   $ 1,379,000 $ 0 $ 0
Cementing | Customer relationships        
Acquired Finite-Lived Intangible Assets [Line Items]        
Impairment of finite lived intangible assets $ 1,000,000      
Impairment of intangible   1,000,000    
Cementing | Trade names        
Acquired Finite-Lived Intangible Assets [Line Items]        
Impairment of finite lived intangible assets $ 200,000      
Impairment of intangible   200,000    
Silverback Energy | Trade names        
Acquired Finite-Lived Intangible Assets [Line Items]        
Impairment of intangible   $ 200,000