Condensed Consolidated Statements of Cash Flows - Unaudited - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Current period net income	$ 135,083	$ (9,485)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Unrealized (gain) loss on derivatives	(136,430)	45,719
Depletion, depreciation and amortization	90,707	76,866
Accretion of asset retirement obligations	476	414
Stock-based compensation expense	3,794	4,587
Deferred income tax provision (benefit)	39,957	(1,013)
Amortization of debt issuance cost	684	643
Changes in operating assets and liabilities
Accounts receivable	36,342	(3,873)
Lease and well equipment inventory	(1,296)	(1,465)
Prepaid expenses and other current assets	174	(936)
Other long-term assets	1,749	9,809
Accounts payable, accrued liabilities and other current liabilities	(58,562)	(41,621)
Royalties payable	384	(7,500)
Advances from joint interest owners	(3,598)	(6,297)
Other long-term liabilities	(92)	(6,608)
Net cash provided by operating activities	109,372	59,240
Investing activities
Oil and natural gas properties capital expenditures	(173,994)	(182,288)
Midstream capital expenditures	(73,439)	(33,340)
Expenditures for other property and equipment	(787)	(807)
Proceeds from sale of assets	0	1,555
Net cash used in investing activities	(248,220)	(214,880)
Financing activities
Borrowings under Credit Agreement	60,000	100,000
Borrowings under San Mateo Credit Facility	19,500	0
Cost to amend Credit Agreement	(660)	0
Proceeds from stock options exercised	45	3,150
Contributions related to formation of San Mateo I	14,700	14,700
Contributions from non-controlling interest owners of less-than-wholly-owned subsidiaries	50,000	12,330
Distributions to non-controlling interest owners of less-than-wholly-owned subsidiaries	(11,515)	(8,330)
Taxes paid related to net share settlement of stock-based compensation	(1,336)	(3,208)
Cash paid under financing lease obligations	(219)	(274)
Net cash provided by financing activities	130,515	118,368
Decrease in cash and restricted cash	(8,333)	(37,272)
Cash and restricted cash at beginning of period	65,128	83,984
Cash and restricted cash at end of period	$ 56,795	$ 46,712