Investment Operations LIHTC Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Tax impact of Income from Equity Method Investments	$ (15,498)	$ (15,706)	$ (13,372)
Investment Tax Credit	14,077	13,542	12,209
Equity Method Investments	137,422	134,570
Income (Loss) from Equity Method Investments	11,440	9,523	10,103
Qualified Affordable Housing Project Investments, Commitment	3,803
Other Commitment	50,000
Affordable Housing Tax Credit Investments [Member]
Schedule of Equity Method Investments [Line Items]
Other Commitment, Due in Next Twelve Months	2,898
Income (Loss) from Affordable Housing Projects, Equity Method Investments	(7,547)	(7,022)	(6,411)
Tax impact of Income from Equity Method Investments	2,641	2,458	2,244
Equity Method Investments	91,300	94,200
Income (Loss) from Equity Method Investments	9,171	$ 8,978	$ 8,042
Other Commitment, Due in Second Year	590
Other Commitment, Due in Third Year	315
Limited Partnerships and Limited Liability Companies [Member]
Schedule of Equity Method Investments [Line Items]
Other Commitment	$ 31,400