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Notes Payable - Components of Notes Payable (Parenthetical) (Detail) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Jun. 16, 2021 | Mar. 17, 2021 | Nov. 05, 2015
Series B senior notes [Member] | 3.68% Series B senior notes due in 2021 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Senior Notes, interest rate |  | 3.68% |  |  |
Senior Notes, year of maturity |  | 2021 |  |  |
Series C senior notes [Member] | 3.84% Series C senior notes due in 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Senior Notes, interest rate | 3.84% | 3.84% |  |  | 3.84%
Senior Notes, year of maturity | 2022 | 2022 |  |  |
Series E senior notes [Member] | 2.35% Series E senior notes due in 2026 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Senior Notes, interest rate | 2.35% |  | 2.35% |  |
Senior Notes, year of maturity | 2026 |  |  |  |
Series D senior notes [Member] | 2.57% Series D senior notes due in 2028 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Senior Notes, interest rate | 2.57% |  |  | 2.57% |
Senior Notes, year of maturity | 2028 |  |  |  |

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