Annual report pursuant to Section 13 and 15(d)

Fair Value Measurement - (Details)

v3.7.0.1
Fair Value Measurement - (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value $ (75,907) $ (37,253)
Level 1    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (1,297) 2,196
Level 2    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (28,042) 2,263
Level 3    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (46,568) (41,712)
Commodity contract derivatives    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (2,239) 4,459
Commodity contract derivatives | Level 1    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (1,297) 2,196
Commodity contract derivatives | Level 2    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (942) 2,263
Commodity contract derivatives | Level 3    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value 0 0
Convertible debt conversion liability    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (27,100)  
Convertible debt conversion liability | Level 1    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value 0  
Convertible debt conversion liability | Level 2    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (27,100)  
Convertible debt conversion liability | Level 3    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value 0  
Contingent consideration for acquisitions    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value (46,568) (41,712)
Contingent consideration for acquisitions | Level 1    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value 0 0
Contingent consideration for acquisitions | Level 2    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value 0 0
Contingent consideration for acquisitions | Level 3    
Assets (liabilities) measured at fair value    
Assets (liabilities), fair value $ (46,568) $ (41,712)