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Fair Value Measurements - Changes in Level 3 (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Collateralized loan obligations |  |
Changes in Level 3 |  |
Beginning balance | $ 2,268 | $ 3,119
Transfers out of Level 3 | (1,308) |
Total gains or losses |  |
Included in earnings (or changes in net assets) | 35 | 40
Included in other comprehensive income | 40 | 21
Purchases, issuances, sales, and settlements |  |
Settlements | (1,035) | (912)
Ending balance |  | 2,268
States and political subdivisions |  |
Changes in Level 3 |  |
Beginning balance | 14,261 | 22,226
Total gains or losses |  |
Included in other comprehensive income | (746) | (796)
Purchases, issuances, sales, and settlements |  |
Purchases | 22,046 | 16,712
Settlements | (27,396) | (23,881)
Ending balance | 8,165 | 14,261
Mortgage servicing rights |  |
Changes in Level 3 |  |
Beginning balance | 6,944 | 6,489
Total gains or losses |  |
Included in earnings (or changes in net assets) | (181) | (270)
Purchases, issuances, sales, and settlements |  |
Issuances | 1,146 | 1,257
Settlements | (552) | (532)
Ending balance | $ 7,357 | $ 6,944

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