Chapter 11 Proceedings - Additional Information (Detail) - USD ($)			1 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended		8 Months Ended
	Apr. 23, 2021	Jan. 22, 2021	Apr. 23, 2021	Jun. 30, 2021	Jun. 30, 2020	Apr. 23, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Jun. 22, 2021	Mar. 31, 2021	Jan. 31, 2021	Apr. 28, 2020	Apr. 26, 2020
Liabilities Subject To Compromise [Line Items]
Line of credit									$ 436,000,000
Reorganization, date plan confirmed							Apr. 08, 2021
Reorganization, effective date of plan							Apr. 23, 2021
Authorizing issuance of shares of common stock representing equity interests percentage	100.00%		100.00%			100.00%
Total capital stock authorized	800,000,000		800,000,000			800,000,000
Common stock, shares authorized	750,000,000		750,000,000	750,000,000		750,000,000	750,000,000		500,000,000
Common stock, par value	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.01
Preferred stock, shares authorized	50,000,000		50,000,000	50,000,000		50,000,000	50,000,000		25,000,000
Preferred stock, par value	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.01
Common stock transferred	30,000,000
New-money commitments to Debtors	$ 114,675,000
New stock warrants issued in exchange for common stock	7,526,894
Common stock, shares issued	100,000,019		100,000,019	100,074,093		100,000,019	100,074,093		145,263,865
Common stock, shares outstanding	100,000,019		100,000,019	100,074,093		100,000,019	100,074,093		138,054,311
Warrants term	5 years		5 years			5 years
Common stock shares registration										22,892,773
Senior notes									$ 2,000,000,000
Payment for professional fees				$ 15,809,000		$ 37,566,000		$ 274,000
Contractual interest expense not recorded			$ 7,124,000		$ 24,635,000	35,390,000		24,635,000
Accrued interest				3,017,000			$ 3,017,000
Interest expense			$ 2,265,000	7,097,000	$ 10,333,000	$ 34,827,000		$ 42,655,000
Computershare Inc. [Member]
Liabilities Subject To Compromise [Line Items]
Warrants issued	7,526,894
Warrants term	5 years		5 years			5 years
Warrants exercise years	5 years
Warrants exercisable percentage	7.00%
Warrants exercise price	$ 29.22		$ 29.22			$ 29.22
Senior Notes [Member]
Liabilities Subject To Compromise [Line Items]
Common stock transferred	70,000,019
Pro rata share received percentage	70.00%
Liabilities subject to compromise principal balance	$ 2,000,000,000.0		$ 2,000,000,000.0			$ 2,000,000,000.0
Liabilities subject to compromise accrued interest	44,900,000		44,900,000			44,900,000
Contractual interest expense not recorded			7,100,000			35,400,000
Senior Secured Term Loan Credit Agreement [Member]
Liabilities Subject To Compromise [Line Items]
Senior notes	$ 100,000,000.0		100,000,000.0			100,000,000.0
Debt instrument maturity date	Apr. 22, 2027
Debt instrument carrying amount	$ 100,000,000.0		100,000,000.0			100,000,000.0
First Lien Notes [Member]
Liabilities Subject To Compromise [Line Items]
Senior notes	$ 85,300,000		85,300,000			85,300,000
Debt instrument maturity date	Apr. 22, 2027
Additional First Lien Notes [Member]
Liabilities Subject To Compromise [Line Items]
Senior notes	$ 39,700,000		39,700,000			39,700,000
Debt instrument carrying amount	0		0			0
Exit Revolving Credit Facility [Member]
Liabilities Subject To Compromise [Line Items]
Line of credit	103,500,000	$ 950,000,000.0	103,500,000	$ 133,500,000		103,500,000	$ 133,500,000					$ 442,000,000.0		$ 436,000,000.0
Amount available for general purposes													$ 442,000,000.0	$ 950,000,000.0
Exit Revolving Credit Facility [Member] | Minimum [Member]
Liabilities Subject To Compromise [Line Items]
Amount available for general purposes	400,000,000.0		$ 400,000,000.0			$ 400,000,000.0
Exit Revolving Credit Facility [Member] | Maximum [Member]
Liabilities Subject To Compromise [Line Items]
Credit facility pro rata share amount of funded loans	$ 100,000,000
First Lien Notes [Member]
Liabilities Subject To Compromise [Line Items]
Senior notes maturity year	2027
First Lien Notes [Member] | Cash Pay Rate [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes	9.00%		9.00%			9.00%
First Lien Notes [Member] | Cash Pay Rate and Payment in Kind Rate [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes	11.00%		11.00%			11.00%
First Lien Notes [Member] | Payment in Kind Rate [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes	13.00%		13.00%			13.00%
Senior Secured Revolving Credit Facility [Member]
Liabilities Subject To Compromise [Line Items]
Amount available for general purposes	$ 400,000,000.0		$ 400,000,000.0			$ 400,000,000.0
Sublimit for issuance of letters of credit	100,000,000.0		100,000,000.0			100,000,000.0
Credit Facility [Member]
Liabilities Subject To Compromise [Line Items]
Accrued interest											$ 35,300,000
Interest expense									$ 23,400,000
5.70% Senior Notes due 2039 [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes		5.70%							5.70%
Senior notes maturity year		2039
Senior notes									$ 500,000,000
3.45% Senior Notes due 2023 [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes		3.45%							3.45%
Senior notes maturity year		2023
Senior notes									$ 250,000,000
4.875% Senior Notes due 2043 [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes		4.875%							4.875%
Senior notes maturity year		2043
Senior notes									$ 750,000,000
7.875% Senior Notes due 2025 [Member]
Liabilities Subject To Compromise [Line Items]
Interest rate of senior notes		7.875%							7.875%
Senior notes maturity year		2025
Senior notes									$ 500,000,000
Exit Term Loan Credit Facility [Member]
Liabilities Subject To Compromise [Line Items]
Line of credit	100,000,000.0		100,000,000.0			100,000,000.0
Senior notes	100,000,000.0		$ 100,000,000.0			$ 100,000,000.0
Maximum portion of facility used to settle RCF claims	$ 200,000,000