Investment in Qualified Affordable Housing Investment in Qualified Affordable Housing (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Amortization Method Qualified Affordable Housing Project Investments, Amortization	$ 1,900	$ 1,800	$ 5,600	$ 5,500
Affordable housing tax credit investments	54,355		54,355		$ 52,947
Affordable Housing Program Obligation	21,282		21,282		$ 14,282
Affordable Housing Tax Credits and Other Tax Benefits, Amount	$ 2,300	$ 2,300	$ 6,900	$ 7,000