Acquisitions - Summary of Purchase Price Allocation and Values of Assets Acquired and Liabilities Assumed (Detail) - BRMR and Everest Merger Sub Inc. [Member] $ in Thousands	Feb. 28, 2019 USD ($)
Business Acquisition [Line Items]
Fair value of the Company’s common stock issued	$ 263,487
Fair value of BRMR share-based and other compensation	12,272
Total Fair Value of Consideration	275,759
Cash and cash equivalents	12,894
Accounts receivable	25,884
Assets held for sale - current	2,296
Other current assets	1,702
Unproved properties	80,843
Proved oil and gas properties	218,866
Other property and equipment	7,059
Other assets	2,461
Operating lease right-of-use asset	7,900
Assets held for sale - long-term	9,611
Total assets acquired	369,516
Accounts payable	(16,571)
Accrued capital expenditures	(5,807)
Accrued liabilities	(28,824)
Operating lease liability - current	(1,979)
Liabilities associated with assets held for sale - current	(7,683)
Asset retirement obligations	(20,188)
Operating lease liability - noncurrent	(5,923)
Liabilities associated with assets held for sale - long-term	(6,782)
Total liabilities assumed	(93,757)
Net identifiable assets	$ 275,759