Long-Term Obligations - Summary of Long-Term Obligations (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
6.125% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Notes issued rate	6.125%	6.125%
Debt instrument maturity period	2023	2023
6.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Notes issued rate	6.625%	6.625%
Debt instrument maturity period	2026	2026