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Fair Value Measurements - Changes in Level 3 (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Interest rate swap agreements net of swap credit valuation
Changes in Level 3 (liabilities)
Beginning balance		$ (6)
Included in earnings (or changes in net assets)		6
Asset-backed securities
Changes in Level 3
Beginning balance	$ 52,941	154,137
Total gains or losses
Included in earnings (or changes in net assets)	(28)	3,178
Included in other comprehensive income	(541)	(1,748)
Purchases, issuances, sales, and settlements
Purchases		63,704
Sales	(27,455)	(135,490)
Ending balance		83,781
Transfers out of Level 3	(24,917)
States and political subdivisions
Changes in Level 3
Beginning balance	118	125
Purchases, issuances, sales, and settlements
Ending balance	118	125
Mortgage servicing rights
Changes in Level 3
Beginning balance	5,462	5,807
Total gains or losses
Included in earnings (or changes in net assets)	(668)	(761)
Purchases, issuances, sales, and settlements
Issuances	1,209	594
Settlements	(533)
Ending balance	$ 5,470	$ 5,640

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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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