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Fair Value Measurements - Changes in Level 3 (Details) - USD ($) $ in Thousands | 9 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016
Collateralized loan obligations |  |
Changes in Level 3 |  |
Beginning balance | $ 3,119 |
Total gains or losses |  |
Included in other comprehensive income | 7 |
Purchases, issuances, sales, and settlements |  |
Settlements | (666) |
Ending balance | 2,492 |
Changes in Level 3 (liabilities) |  |
Included in earnings (or changes in net assets) | 32 |
States and political subdivisions |  |
Changes in Level 3 |  |
Beginning balance | 22,226 | $ 111
Total gains or losses |  |
Included in other comprehensive income | (501) | 9
Purchases, issuances, sales, and settlements |  |
Purchases | 10,994 |
Settlements | (20,359) | (78)
Ending balance | 12,360 | 0
Transfers out of Level 3 |  | (42)
Mortgage servicing rights |  |
Changes in Level 3 |  |
Beginning balance | 6,489 | 5,847
Total gains or losses |  |
Included in earnings (or changes in net assets) |  | (1,394)
Purchases, issuances, sales, and settlements |  |
Issuances | 951 | 1,148
Settlements | (402) | (526)
Ending balance | 6,684 | $ 5,075
Changes in Level 3 (liabilities) |  |
Included in earnings (or changes in net assets) | $ (354) |

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- Definition Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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