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Fair Value Measurements - Additional Information (Detail) - USD ($)
3 Months Ended
Jun. 30, 2016
Dec. 31, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Assets or liabilities measured at fair value on recurring basis   $ 0
Fixed payments to partner, year 2017-06  
Fixed payments to partner, year 2024-06  
Purchase of outstanding preferred shares, year 2024  
Additional paid in capital excess of cash contributed $ 5,200,000  
Cash contribution by partner in joint venture 3,000,000  
Level 3 [Member]    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Joint Venture liability (level 3) 8,200,000  
Level 3 [Member] | Other Noncurrent Liabilities [Member]    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Joint Venture liability (level 3) 7,200,000  
Level 3 [Member] | Other current liabilities [Member]    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Joint Venture liability (level 3) $ 1,000,000