FDIC Indemnification Indemnification Asset and True-up Payment Obligation (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
FDIC-Assisted Acquisition [Abstract]
FDIC indemnification asset, expense	$ 1,403	$ 8,040	$ (36,398)
(Repayment to) reimbursement to the FDIC for the termination of shared-loss agreements	$ (10,125)	$ 1,573	$ 90,697