Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
ASU 2016-02 Lease assets and liabilities recognition	$ 19,000
Operating Lease, Liability	16,099
Operating lease costs	3,273
Variable Lease, Cost	3,122
Short-term Lease, Cost	55,161
Lease, Cost	61,556
Operating cash flows from operating leases	$ 199
Operating Lease, Weighted Average Remaining Lease Term	5 years 11 months
Weighted average discount rate	4.70%
Drilling rig commitments [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability	$ 10,543
Surface use agreements [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability	3,791
Field equipment [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability	1,384
Other [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability	$ 381