Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2019		Dec. 31, 2018
Assets
Derivatives	$ 144,422		$ 233,629
Liabilities
Derivatives	82,690		75,349
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Derivatives	0	[1]	0	[2]
Liabilities
Derivatives	0	[1]	0	[2]
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Derivatives	144,422	[1]	233,629	[2]
Liabilities
Derivatives	82,690	[1]	75,349	[2]
Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Derivatives	0	[1]	0	[2]
Liabilities
Derivatives	$ 0	[1]	$ 0	[2]

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

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