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Short-Term and Long-Term Borrowings - Narrative (Details) - USD ($) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2021 | Mar. 31, 2022 | Jun. 10, 2021
Senior Notes |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate principal amount |  |  | $ 230,000,000
Proceeds from issuance of debt | $ 140,000,000 |  |
Series 2021A Senior Unsecured Notes |  |  |
Debt Instrument [Line Items] |  |  |
Interest rate (as a percent) |  | 2.74% |
Series 2021A Senior Unsecured Notes | Senior Notes |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate principal amount |  |  | $ 40,000,000
Interest rate (as a percent) |  |  | 2.74%
Series 2021B Senior Unsecured Notes |  |  |
Debt Instrument [Line Items] |  |  |
Interest rate (as a percent) |  | 3.69% |
Series 2021B Senior Unsecured Notes | Senior Notes |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate principal amount |  |  | $ 100,000,000
Interest rate (as a percent) |  |  | 3.69%
Senior Unsecured Notes 3.77%, Series A, Due May 20, 2052 | Senior Notes |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate principal amount |  |  | $ 90,000,000
Interest rate (as a percent) |  |  | 3.77%
Minimum |  |  |
Debt Instrument [Line Items] |  |  |
Interest and dividend coverage ratio |  | 1.50 |
Maximum |  |  |
Debt Instrument [Line Items] |  |  |
Debt to total capitalization ratio |  | 60.00% |

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