Debt - Schedule of Minimum Adjusted EBITDA (Detail) - Superpriority Credit Agreement [Member] - Subsequent Event [Member]	Oct. 21, 2019 USD ($)
December 31, 2019 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	$ 430,000,000
March 31, 2020 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	470,000,000
June 30, 2020 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	530,000,000
September 30, 2020 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	880,000,000
December 31, 2020 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	960,000,000
March 31, 2021 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	1,090,000,000
June 30, 2021 [Member]
Debt Instrument [Line Items]
Minimum Adjusted EBITDA	$ 1,210,000,000