Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of minimum future lease payments

The following is a schedule of minimum future lease payments with commitments that have initial or remaining noncancelable lease terms in excess of one year as of December 31, 2018:

Year Ending December 31,	Drilling Rig Commitments		Sand Supply Agreement		Office and Equipment Leases
	(in thousands)
2019	$	18,976	9,000		$	9,019
2020	414		9,000		3,827
2021	—		9,000		1,452
2022	—		9,000		583
2023	—		2,250		—
Thereafter	—		—		—
Total	$	19,390	$	38,250	$	14,881

Schedule of rent expense

The following table presents rent expense for the years ended December 31, 2018, 2017 and 2016.

	Year ended December 31,
	2018		2017		2016
	(in thousands)
Rent Expense	$	751	$	2,412	$	1,961