Summary of Significant Accounting Policies (Variable Interest Entities) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Unfunded commitments to fund low-income housing partnerships	$ 13,236
Other Assets
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	82,400	$ 85,900
Other Liabilities
Variable Interest Entity [Line Items]
Unfunded commitments to fund low-income housing partnerships	$ 13,200	$ 15,200
Low-income housing partnerships
Variable Interest Entity [Line Items]
Period over which tax credits or benefits are generally recognized (in years)	10 years
Solar energy partnerships
Variable Interest Entity [Line Items]
Period over which tax credits or benefits are generally recognized (in years)	6 years