Fresh Start Accounting - Schedule of Fresh Start Adjustments to Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Apr. 24, 2021	Apr. 23, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 27,296			$ 79,982	$ 405,869
Restricted cash	24,266			35,447	24,511
Accounts receivable	175,633			134,906	136,222
Less: allowance for credit losses	(5,614)			(5,555)	(5,562)
Accounts receivable, net	170,019			129,351	130,660
Prepaid expenses and other current assets	62,101			58,655	62,275
Assets held for sale	1,000			1,000	2,000
Total current assets	284,682			304,435	625,315
Drilling and other property and equipment, net of accumulated depreciation	1,328,825			1,354,650	4,122,809
Other assets	78,226			57,047	200,329
Noncurrent deferred tax assets, net				6,716
Total assets	1,691,733			1,722,848	4,948,453
Current liabilities:
Accounts payable	35,725			65,401	33,437
Accrued liabilities	134,186			123,055	140,788
Current finance lease liabilities	15,599			15,148
Taxes payable	29,245			22,034	27,214
Total current liabilities	214,755			225,638	201,439
Deferred tax liability	2,433				28,338
Other liabilities	128,122			117,499	117,305
Noncurrent finance lease liabilities	152,457			158,919
Long-term debt	306,145			285,982
Total liabilities not subject to compromise	803,912			788,038	347,082
Liabilities subject to compromise					2,618,805
Stockholders’ equity:
Predecessor or Successor preferred stock
Predecessor or Successor common stock	10				1,453
Predecessor treasury stock, at cost					(206,163)
Successor additional paid-in capital				934,800
(Accumulated deficit) retained earnings	(52,475)				157,297
Total stockholders’ equity	887,821	$ 888,509	$ 934,810	934,810	1,982,566	$ 2,132,104	$ 2,230,689	$ 3,232,210
Total liabilities and stockholders’ equity	1,691,733			1,722,848	4,948,453
Fresh Start Adjustments
Current assets:
Accounts receivable				802
Accounts receivable, net				802
Prepaid expenses and other current assets				(34,455)
Total current assets				(33,653)
Drilling and other property and equipment, net of accumulated depreciation				(2,720,485)
Other assets				(10,282)
Noncurrent deferred tax assets, net				6,716
Total assets				(2,757,704)
Current liabilities:
Accrued liabilities				(55,961)
Total current liabilities				(55,961)
Deferred tax liability				(34,447)
Deferred tax asset, reclassification				7,518
Other liabilities				(9,837)
Total liabilities not subject to compromise				(92,727)
Stockholders’ equity:
Predecessor or Successor preferred stock
(Accumulated deficit) retained earnings				(2,664,977)
Total stockholders’ equity				(2,664,977)
Total liabilities and stockholders’ equity				(2,757,704)
Preferred Stock
Stockholders’ equity:
Predecessor or Successor preferred stock
Preferred Stock | Fresh Start Adjustments
Stockholders’ equity:
Predecessor or Successor preferred stock
Common Stock [Member]
Stockholders’ equity:
Predecessor or Successor common stock				10
Total stockholders’ equity	$ 10	$ 10	$ 10		$ 1,453	$ 1,453	$ 1,453	$ 1,448
Previously Reported | Reorganization, Chapter 11, Predecessor, before Adjustment
Current assets:
Cash and cash equivalents				333,699
Restricted cash				3,274
Accounts receivable				134,104
Less: allowance for credit losses				(5,555)
Accounts receivable, net				128,549
Prepaid expenses and other current assets				108,594
Assets held for sale				1,000
Total current assets				575,116
Drilling and other property and equipment, net of accumulated depreciation				3,892,150
Other assets				179,783
Total assets				4,647,049
Current liabilities:
Accounts payable				66,397
Accrued liabilities				246,141
Short-term debt				442,034
Taxes payable				22,034
Total current liabilities				776,606
Deferred tax liability				23,060
Other liabilities				217,434
Total liabilities not subject to compromise				1,017,100
Liabilities subject to compromise				2,044,877
Stockholders’ equity:
Predecessor or Successor preferred stock
Predecessor or Successor common stock				1,453
Predecessor additional paid-in capital				2,029,978
Predecessor treasury stock, at cost				(206,163)
(Accumulated deficit) retained earnings				(240,196)
Total stockholders’ equity				1,585,072
Total liabilities and stockholders’ equity				4,647,049
Previously Reported | Preferred Stock | Reorganization, Chapter 11, Predecessor, before Adjustment
Stockholders’ equity:
Predecessor or Successor preferred stock
Reorganization Adjustments | Reorganization, Chapter 11, Predecessor, before Adjustment
Current assets:
Cash and cash equivalents				(253,717)
Restricted cash				32,173
Prepaid expenses and other current assets				(15,484)
Total current assets				(237,028)
Drilling and other property and equipment, net of accumulated depreciation				182,985
Other assets				(112,454)
Total assets				(166,497)
Current liabilities:
Accounts payable				(996)
Accrued liabilities				(67,125)
Short-term debt				(442,034)
Current finance lease liabilities				15,148
Total current liabilities				(495,007)
Deferred tax liability				3,869
Other liabilities				(90,098)
Noncurrent finance lease liabilities				158,919
Long-term debt				285,982
Total liabilities not subject to compromise				(136,335)
Liabilities subject to compromise				(2,044,877)
Stockholders’ equity:
Predecessor or Successor preferred stock
Predecessor or Successor common stock				(1,453)
Predecessor additional paid-in capital				(2,029,978)
Predecessor treasury stock, at cost				206,163
Successor additional paid-in capital				934,800
(Accumulated deficit) retained earnings				2,905,173
Total stockholders’ equity				2,014,715
Total liabilities and stockholders’ equity				(166,497)
Reorganization Adjustments | Preferred Stock | Reorganization, Chapter 11, Predecessor, before Adjustment
Stockholders’ equity:
Predecessor or Successor preferred stock
Reorganization Adjustments | Common Stock [Member] | Reorganization, Chapter 11, Predecessor, before Adjustment
Stockholders’ equity:
Predecessor or Successor common stock				$ 10