Reorganization - Schedule of Liabilities Subject to Compromise (Detail) $ in Millions	Mar. 31, 2020 USD ($)
Reorganization [Line Items]
Total liabilities subject to compromise	$ 4,578
Debtor in Possession [Member]
Reorganization [Line Items]
Allowed claims on Term facility and Revolving credit facility	96
Interest rate derivative	47
Total liabilities subject to compromise	4,578
Debtor in Possession [Member] | Term Facility [Member]
Reorganization [Line Items]
Debt, accrued and unpaid interest	2,220
Debtor in Possession [Member] | 10.625% Senior Notes [Member]
Reorganization [Line Items]
Debt, accrued and unpaid interest	1,300
Debtor in Possession [Member] | Accrued and Unpaid Interest [Member]
Reorganization [Line Items]
Debt, accrued and unpaid interest	114
Debtor in Possession [Member] | Revolving Credit Facility [Member]
Reorganization [Line Items]
Debt, accrued and unpaid interest	$ 801