Fair Value of Assets and Liabilities - Additional Information (Details) - Senior Notes	Dec. 31, 2020	Dec. 31, 2019	Sep. 25, 2014	Mar. 19, 2013
6.00% Senior Notes due 2026
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Stated interest rate	6.00%	6.00%
5.125% Senior Notes due 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Stated interest rate	5.125%	5.125%		5.125%
5.875% Senior Notes due 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Stated interest rate	5.875%	5.875%	5.875%
5.875% Senior Notes due 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Stated interest rate	5.875%	5.875%