Variable Interest Entities (Summary of the Impact of Qualifying LIHTC Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Low income housing tax credits
Variable Interest Entity [Line Items]
Amortization of qualifying LIHTC investments	$ 3,774	$ 5,445	$ 8,414	$ 10,073
Affordable Housing Tax Credits and Other Tax Benefits	(3,103)	(2,615)	(8,101)	(7,672)
Other tax benefits related to qualifying LIHTC investments
Variable Interest Entity [Line Items]
Affordable Housing Tax Credits and Other Tax Benefits	$ (2,478)	$ (6,131)	$ (4,307)	$ (8,310)