Fair Value Measurements Fair Value (Details) - USD ($) $ in Thousands		Jun. 30, 2017		Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 168,156		$ 122,096
Property, Plant and Equipment, Net		5,346,411		6,081,354
Derivative Liability, Fair Value, Gross Liability		106,211		213,804
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant and Equipment, Net	[1]			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant and Equipment, Net	[1]			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant and Equipment, Net	[1]			88,205
Derivatives not designated as hedging instruments | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		0	[2]	0	[3]
Derivative Liability, Fair Value, Gross Liability		0	[2]	0	[3]
Derivatives not designated as hedging instruments | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		168,156	[2]	122,096	[3]
Derivative Liability, Fair Value, Gross Liability		106,211	[2]	213,804	[3]
Derivatives not designated as hedging instruments | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		0	[2]	0	[3]
Derivative Liability, Fair Value, Gross Liability		$ 0	[2]	$ 0	[3]

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

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

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