Fair Value Accounting (Assets Measured at Fair Value on Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring Basis - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	$ 6,828	$ 5,776	$ 7,548	$ 5,808
Other loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	0	0	0	3,519
Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	0	280	0	518
Other assets held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value adjustment	$ 499	$ 0	$ 499	$ 238