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Fair Value Option and Fair Value Measurements - Changes in Level 3 (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended									9 Months Ended
	Sep. 30, 2014 Interest rate swap agreements net of swap credit valuation	Sep. 30, 2013 Interest rate swap agreements net of swap credit valuation	Sep. 30, 2013 Collateralized debt obligations	Sep. 30, 2014 Asset-backed securities	Sep. 30, 2013 Asset-backed securities	Sep. 30, 2014 States and political subdivisions	Dec. 31, 2013 States and political subdivisions	Sep. 30, 2013 States and political subdivisions	Dec. 31, 2012 States and political subdivisions	Sep. 30, 2014 Mortgage servicing rights	Sep. 30, 2013 Mortgage servicing rights
Changes in Level 3
Beginning balance			$ 9,957	$ 154,137		$ 125	$ 125	$ 132	$ 132	$ 5,807	$ 4,116
Total gains or losses
Included in earnings (or changes in net assets)			178	3,178	485					(761)	81
Included in other comprehensive income			1,898	(1,748)	(1,487)
Purchases, issuances, sales, and settlements
Purchases				63,704	168,753
Issuances										594	1,259
Settlements			(946)
Sales				(135,490)	(20,539)
Ending balance			11,087	83,781	147,212	125	125	132	132	5,640	5,456
Changes in Level 3 (liabilities)
Beginning balance	(6)	(47)
Included in earnings (or changes in net assets)	6	34
Ending balance		$ (13)

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