Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Current derivative asset		$ 58,198	$ 23,374
Long-term derivative asset	[1]	11,571
Total derivative instruments		69,769
Current derivative liability		20,692	$ 62,350
Long-term derivative liability	[2]	9,382
Total derivative instruments		30,074
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Current derivative asset		58,198
Long-term derivative asset	[1]	11,571
Total derivative instruments		69,769
Current derivative liability		20,692
Long-term derivative liability	[2]	9,382
Total derivative instruments		$ 30,074

[1] Included in Other assets in the Condensed Consolidated Balance Sheet.

[2] Included in Other long-term obligations in the Condensed Consolidated Balance Sheet.