Fair Value Measurements Fair Value (Details) - USD ($) $ in Thousands		Mar. 31, 2018		Dec. 31, 2017
Assets
Derivatives		$ 112,424		$ 104,628
Liabilities
Derivatives		234,780		243,984
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total property and equipment, net	[1]	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total property and equipment, net	[1]	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total property and equipment, net	[1]	192,000
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Derivatives		0	[2]	0	[3]
Liabilities
Derivatives		0	[2]	0	[3]
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Derivatives		112,424	[2]	104,628	[3]
Liabilities
Derivatives		234,780	[2]	243,984	[3]
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Derivatives		0	[2]	0	[3]
Liabilities
Derivatives		$ 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.