Investment in Qualified Affordable Housing Investment in Qualified Affordable Housing (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Amortization Method Qualified Affordable Housing Project Investments, Amortization	$ 1,900	$ 1,900	$ 5,553	$ 5,592
Affordable housing tax credit investments	52,116		52,116		$ 49,669
Affordable Housing Program Obligation	22,282		22,282		$ 14,282
Affordable Housing Tax Credits and Other Tax Benefits, Amount	$ 2,000	$ 2,300	$ 6,900	$ 6,900