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Commitments and Contingencies - Settlement and Royalty Indemnity, Narrative (Details) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Nov. 30, 2011
Aug. 31, 2011
Dec. 31, 2016
Dec. 31, 2016
Dec. 31, 2015
Loss Contingencies [Line Items]          
Reduction to royalty award accrual     $ 4,000,000 $ 4,000,000  
Settlement and royalty indemnification     5,656,000 5,656,000 $ 6,502,000
Settlement and royalty indemnification, long-term     $ 5,382,000 $ 5,382,000 $ 13,797,000
Norit Litigation          
Loss Contingencies [Line Items]          
Period of payment for equity award after each quarter   3 months      
Ability to pay dividends, percent of market fair value 50.00%        
Benchmark for earnings for increase in letters of credit $ 20,000,000.0        
Increase in letters of credit as collateral 5,000,000        
Maximum amount of increase in letters of credit based on dividends or earnings $ 7,500,000