Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income (loss)	$ 299,764	$ 138,007	$ (97,057)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Unrealized (gain) loss on derivatives	(65,085)	(9,715)	41,238
Depletion, depreciation and amortization	265,142	177,502	122,048
Accretion of asset retirement obligations	1,530	1,290	1,182
Full-cost ceiling impairment	0	0	158,633
Stock-based compensation expense	17,200	16,654	12,362
Prepayment premium on extinguishment of debt	31,226	0	0
Deferred income tax benefit	(7,236)	0	0
Amortization of debt issuance cost	1,357	468	1,148
Net loss (gain) on asset sales and inventory impairment	196	(23)	(107,277)
Changes in operating assets and liabilities
Accounts receivable	(4,934)	(82,549)	(14,259)
Lease and well equipment inventory	(12,176)	(3,623)	(700)
Prepaid expenses	(1,770)	(2,960)	(124)
Other assets	3,418	(6,425)	490
Accounts payable, accrued liabilities and other current liabilities	68,647	33,559	6,611
Royalties payable	3,418	37,370	7,495
Advances from joint interest owners	8,179	1,089	1,000
Income taxes payable	0	0	(2,848)
Other long-term liabilities	(353)	(1,519)	4,144
Net cash provided by operating activities	608,523	299,125	134,086
Investing activities
Oil and natural gas properties capital expenditures	(1,357,802)	(699,445)	(379,067)
Expenditures for other property and equipment	(165,784)	(120,816)	(74,845)
Proceeds from sale of assets	8,333	977	5,173
Net cash used in investing activities	(1,515,253)	(819,284)	(448,739)
Financing activities
Repayments of borrowings	(370,000)	0	(120,000)
Borrowings under Credit Agreement	410,000	0	120,000
Borrowings under San Mateo Credit Facility	220,000	0	0
Cost to enter into or amend credit facilities	(3,077)	0	0
Proceeds from issuance of senior unsecured notes	1,051,500	0	184,625
Cost to issue senior unsecured notes	(14,098)	0	(2,734)
Purchase of senior unsecured notes	(605,780)	0	0
Proceeds from issuance of common stock	226,612	208,720	288,510
Cost to issue equity	(204)	(280)	(847)
Proceeds from stock options exercised	815	2,920	100
Contributions related to formation of Joint Venture	14,700	171,500	0
Contributions from non-controlling interest owners of less-than-wholly-owned subsidiaries	85,750	44,100	0
Distributions to non-controlling interest owners of less-than-wholly-owned subsidiaries	(121,520)	(10,045)	0
Taxes paid related to net share settlement of stock-based compensation	(6,466)	(5,763)	(1,948)
Purchase of non-controlling interest of less-than-wholly-owned subsidiary	0	(2,653)	0
Net cash provided by financing activities	888,232	408,499	467,706
(Decrease) increase in cash and restricted cash	(18,498)	(111,660)	153,053
Cash and restricted cash at beginning of year	102,482	214,142	61,089
Cash and restricted cash at end of year	$ 83,984	$ 102,482	$ 214,142