Basis of Presentation and Summary of Significant Accounting Policies - Changes in the Balance of Each Component of Accumulated Other Comprehensive Earnings (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 30, 2026 |
Mar. 31, 2026 |
Jun. 30, 2025 |
Mar. 31, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Changes in the balance of each component of accumulated other comprehensive earnings (loss) | ||||||
| Beginning balance | $ 1,796,390 | $ 1,778,196 | $ 1,604,212 | $ 1,521,967 | $ 1,778,196 | $ 1,521,967 |
| Net current-period other comprehensive earnings (loss) | (2,314) | (25,366) | 18,701 | 30,030 | (27,680) | 48,731 |
| Ending balance | 1,752,115 | 1,796,390 | 1,734,661 | 1,604,212 | 1,752,115 | 1,734,661 |
| Balance of securities for which an allowance for credit losses has been recognized in net earnings | 1,465 | 1,102 | 1,465 | 1,102 | ||
| Unrealized Gains and Losses on Available-for-Sale Securities | ||||||
| Changes in the balance of each component of accumulated other comprehensive earnings (loss) | ||||||
| Beginning balance | (113,440) | (88,074) | (143,693) | (173,723) | (88,074) | (173,723) |
| Other comprehensive earnings before reclassifications | (2,655) | 17,922 | (28,632) | 47,822 | ||
| Amounts reclassified from accumulated other comprehensive earnings | 341 | 779 | 952 | 909 | ||
| Net current-period other comprehensive earnings (loss) | (2,314) | 18,701 | (27,680) | 48,731 | ||
| Ending balance | $ (115,754) | $ (113,440) | $ (124,992) | $ (143,693) | $ (115,754) | $ (124,992) |
| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
|
| X | ||||||||||
- Definition Amount, after tax, of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with allowance for credit loss. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount after tax of other comprehensive income (loss) attributable to parent entity. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Details
|