Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Schedule of Losses or Gains on Financial Instruments Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment gain	$ (49,884)	$ (786)	$ (111)
Financial instruments loss	(46,215)	12,296	15,929
Commodity price derivative loss
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative loss (gain)	3,642	13,972	17,327
Foreign currency derivative loss (gain)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative loss (gain)	$ 27	$ (890)	$ (1,287)