Leases - Components of Lease Costs (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Finance lease cost - interest on lease liabilities	[1]	$ 4,040	$ 4,867	$ 8,305	$ 9,861
Operating lease cost, excluding short-term leases	[2]	866	763	1,732	1,526
Short-term lease cost	[3]	15,748	27,630	19,283	64,239
Variable lease cost	[4]	3	3	6	5
Total lease cost		$ 20,657	$ 33,263	$ 29,326	$ 75,631

[1] The Helix Producer I (the “HP-I”) is utilized in the Company’s oil and natural gas development activities and the right-of-use asset was capitalized and included in proved property and depleted as part of the full cost pool. Once items are included in the full cost pool, they are indistinguishable from other proved properties. The capitalized costs within the full cost pool are amortized over the life of the total proved reserved using the unit-of-production method, computed quarterly.

[2] Operating lease cost reflect a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a straight-line basis.

[3] Short-term lease costs are reported at gross amounts and primarily represent costs incurred for drilling rigs, most of which are short-term contracts not recognized as a right-of-use asset and lease liability on the balance sheet.

[4] Variable lease costs primarily represent differences between minimum payment obligations and actual operating charges incurred by the Company related to its long-term leases.