Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Activity in the Allowance for Covered Loan Losses) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Allowance for Covered Loan Losses [Roll Forward]
Balance at beginning of period	$ 1,322
Allowance for covered loan losses transferred to allowance for loan losses subsequent to loss share termination or expiration	(742)
Provision for covered loan losses before benefit attributable to FDIC loss share agreements	(1,063)
Benefit attributable to FDIC loss share agreements	1,592
Net provision for covered loan losses and transfer from allowance for covered loan losses to allowance for loan losses	(213)
Increase in FDIC indemnification liability	(1,592)
Loans charged-off	(517)
Recoveries of loans charged-off	1,000
Net recoveries	483
Balance at end of period	$ 0