| Derivative Financial Instruments - Cash Receipts (Payments) on Derivative Settlements, Net Included within Net Cash Provided by Operating Activities (Details) - USD ($) $ in Thousands | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | |
| Derivative Instruments And Hedging Activities Disclosure [Abstract] | |||
| Derivatives cash (payments) receipts, net | $ (28,164) | $ 4,199 | $ 4,746 | 
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- References No definition available. 
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- Definition Cash proceeds payments on derivative settlements net operating activities. No definition available. 
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