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Short-Term and Long-Term Borrowings - Breakdown of Outstanding Long-term Debt (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Debt Instrument [Line Items] |  |
Long-term debt | $ 767,000 | $ 767,169
Current Maturities Net of Unamortized Debt Issuance Costs | 169,962 | 140,087
Unamortized Long-Term Debt Issuance Costs | 2,419 | 2,650
Total Long-Term Debt Net of Unamortized Debt Issuance Costs | $ 594,619 | 624,432
Guaranteed Senior Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.55% |
Long-term debt | $ 80,000 | 80,000
Series 2011A Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 4.63% |
Long-term debt | $ 140,000 | 140,000
Series 2007B Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 6.15% |
Long-term debt | $ 30,000 | 30,000
Series 2007C Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 6.37% |
Long-term debt | $ 42,000 | 42,000
Series 2013A Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 4.68% |
Long-term debt | $ 60,000 | 60,000
Series 2019A Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.07% |
Long-term debt | $ 10,000 | 10,000
Series 2020A Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.22% |
Long-term debt | $ 10,000 | 10,000
Series 2020B Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.22% |
Long-term debt | $ 40,000 | 40,000
Series 2007D Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 6.47% |
Long-term debt | $ 50,000 | 50,000
Series 2019B Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.52% |
Long-term debt | $ 26,000 | 26,000
Series 2020C Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.62% |
Long-term debt | $ 10,000 | 10,000
Series 2013B Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 5.47% |
Long-term debt | $ 90,000 | 90,000
Series 2018A Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 4.07% |
Long-term debt | $ 100,000 | 100,000
Series 2019C Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.82% |
Long-term debt | $ 64,000 | 64,000
Series 2020D Senior Unsecured Notes |  |
Debt Instrument [Line Items] |  |
Rate | 3.92% |
Long-term debt | $ 15,000 | 15,000
PACE Note |  |
Debt Instrument [Line Items] |  |
Rate | 2.54% |
Long-term debt | $ 0 | $ 169

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