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Fair Value Measurements - Changes in Level 3 (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Asset-backed securities
Changes in Level 3
Beginning balance			$ 52,941
Total gains or losses
Included in earnings (or changes in net assets)			(28)
Included in other comprehensive income			(541)
Purchases, issuances, sales, and settlements
Sales	$ (27,455)
Transfers out of Level 3			(24,917)
States and political subdivisions
Changes in Level 3
Beginning balance		$ 111	118
Total gains or losses
Included in other comprehensive income		9
Purchases, issuances, sales, and settlements
Settlements		(78)
Ending balance	118		118
Transfers out of Level 3		(42)
Mortgage servicing rights
Changes in Level 3
Beginning balance		5,847	5,462
Total gains or losses
Included in earnings (or changes in net assets)		(1,394)	(668)
Purchases, issuances, sales, and settlements
Issuances	1,209	1,148
Settlements	(533)	(526)
Ending balance	$ 5,470	$ 5,075	$ 5,470

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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.

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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.

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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.

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Amount of sale 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.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value 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.

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