Fair Value Accounting (Assets Measured at Fair Value on Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring Basis - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	$ 720	$ 2,230
Other loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	1,512	3,519
Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	731	399
Other assets held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	$ 107	$ 238