Estimated Fair Value of Outstanding Debt Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	$ 858,755	$ 858,755
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	703,707	870,794
3.95% Senior Notes Due 2028 | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	509,505	509,505
3.95% Senior Notes Due 2028 | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	415,466	511,652
5.15% Senior Notes Due 2029 | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	349,250	349,250
5.15% Senior Notes Due 2029 | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	$ 288,241	$ 359,142