Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of the Company's property and equipment

The following table presents a summary of the Company’s property and equipment balances as of December 31, 2017 and 2016 (in thousands).

	December 31,
	2017			2016
Oil and natural gas properties
Evaluated (subject to amortization)	$	3,004,770		$	2,408,305
Unproved and unevaluated (not subject to amortization)	637,396			479,736
Total oil and natural gas properties	3,642,166			2,888,041
Accumulated depletion	(2,021,169		)	(1,850,882		)
Net oil and natural gas properties	1,620,997			1,037,159
Midstream and other property and equipment
Midstream equipment and facilities	258,725			145,662
Furniture, fixtures and other equipment	6,109			5,487
Software	7,942			3,206
Land	2,892			1,437
Leasehold improvements	5,428			5,003
Total midstream and other property and equipment	281,096			160,795
Accumulated depreciation	(20,637		)	(13,429		)
Net midstream and other property and equipment	260,459			147,366
Net property and equipment	$	1,881,456		$	1,184,525

Breakdown of the Company's unproved and unevaluated property costs not subject to amortization

The following table provides a breakdown of the Company’s unproved and unevaluated property costs not subject to amortization as of December 31, 2017 and the year in which these costs were incurred (in thousands).

Description	2017		2016		2015		2014 and prior		Total
Costs incurred for
Property acquisition	$	213,076	$	125,689	$	222,912	$	45,809	$	607,486
Exploration wells	16,688		988		547		—		18,223
Development wells	11,396		272		19		—		11,687
Total	$	241,160	$	126,949	$	223,478	$	45,809	$	637,396