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Fair Value Measurements - Changes in Level 3 (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Changes in Level 3 |  |
Beginning balance | $ 3,119 |
Total gains or losses |  |
Included in earnings (or changes in net assets) | 40 |
Included in other comprehensive income | 21 | $ (82)
Purchases, issuances, sales, and settlements |  |
Settlements | (912) |
Ending balance |  | 3,119
Changes in Level 3 (liabilities) |  |
Beginning balance | (3,119) |
Ending balance | 2,268 | 3,119
Collateralized loan obligations |  |
Purchases, issuances, sales, and settlements |  |
Transfers into Level 3 |  | 3,201
States and political subdivisions |  |
Changes in Level 3 |  |
Beginning balance | 22,226 | 111
Total gains or losses |  |
Included in other comprehensive income | (796) | 87
Purchases, issuances, sales, and settlements |  |
Purchases | 16,712 | 14,296
Settlements | (23,881) | (81)
Ending balance | 14,261 | 22,226
Transfers into Level 3 |  | 7,813
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) | (270) | (215)
Purchases, issuances, sales, and settlements |  |
Issuances | 1,257 | 1,561
Settlements | (532) | (704)
Ending balance | $ 6,944 | $ 6,489

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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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- Definition Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy. + 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)(3) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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