Investment in Qualified Affordable Housing Investment in Qualified Affordable Housing (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Amortization Method Qualified Affordable Housing Project Investments, Amortization	$ 1,900	$ 1,900	$ 3,702	$ 3,728
Affordable housing tax credit investments	45,967		45,967		$ 49,669
Affordable Housing Program Obligation	14,282		14,282		$ 14,282
Affordable Housing Tax Credits and Other Tax Benefits, Amount	$ 2,200	$ 2,400	$ 4,900	$ 4,900