Variable Interest Entities Amortization Expense and Tax Credits and Other Tax Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investments in Qualified Affordable Housing Projects
Amortization expense	$ 682	$ 258	$ 1,825	$ 867
Tax credits and other tax benefits recognized	$ 1,040	$ 322	$ 2,792	$ 1,145