Fair Value Measurements (Level 3 Valuation Techniques) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 1,609	$ 13,624	$ 0
Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 1,609
Valuation, Income Approach | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Assumptions, Expected Volatility Rate for a Commodity	12.60%
Valuation, Income Approach | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Assumptions, Expected Volatility Rate for a Commodity	34.50%