Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2016		Dec. 31, 2015
Assets:
Derivatives	$ 122,096		$ 488,411
Property, Plant and Equipment, Other, Net	137,753		153,100
Liabilities [Abstract]
Derivative Liability, Fair Value, Gross Liability	213,804		8
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Derivatives	0	[1]	0	[2]
Liabilities [Abstract]
Derivative Liability, Fair Value, Gross Liability	0	[1]	0	[2]
Net Profits Plan Liability Noncurrent	0	[1]	0	[2]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Derivatives	122,096	[1]	488,411	[2]
Liabilities [Abstract]
Derivative Liability, Fair Value, Gross Liability	213,804	[1]	8	[2]
Net Profits Plan Liability Noncurrent	0	[1]	0	[2]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Derivatives	0	[1]	0	[2]
Liabilities [Abstract]
Derivative Liability, Fair Value, Gross Liability	0	[1]	0	[2]
Net Profits Plan Liability Noncurrent	411	[1]	7,611	[2]
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Property, Plant and Equipment, Other, Net	0	[3]	0	[4]
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Property, Plant and Equipment, Other, Net	0	[3]	0	[4]
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Property, Plant and Equipment, Other, Net	$ 88,205	[3]	$ 124,813	[4]

[1] This represents a financial asset or liability that is measured at fair value on a recurring basis.

[2] This represents a financial asset or liability that is measured at fair value on a recurring basis.

[3] This represents a non-financial asset that is measured at fair value on a nonrecurring basis.

[4] This represents a non-financial asset that is measured at fair value on a nonrecurring basis.