Financial Information for the Company and Its Subsidiaries - Additional Information (Detail)	Dec. 31, 2020	Oct. 14, 2020	Jun. 24, 2020	Dec. 31, 2019	Feb. 16, 2016	Sep. 21, 2015	Feb. 11, 2015	Jul. 01, 2014	Mar. 12, 2013
6.125% Senior Notes Due 2021 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	6.125%			6.125%					6.125%
5.125% Senior Notes Due 2022 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	5.125%			5.125%				5.125%
5.625% Senior Notes Due 2023 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	5.625%			5.625%		5.625%	5.625%
6.500% Senior Notes Due 2024 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	6.50%			6.50%	6.50%
5.500% Senior Notes due 2028 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	5.50%		5.50%	5.50%
5.000% Senior Notes due 2029 [Member]
Line of Credit Facility [Line Items]
Debt instrument interest rate	5.00%	5.00%		5.00%