FDIC Shared-Loss Receivable FDIC Shared-Loss Payable (Changes in Payable to FDIC) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
FDIC Shared-Payable [Abstract]
FDIC shared-loss payable	$ 102,466	$ 98,013	$ 101,342	$ 97,008
Accretion expense	992	954
Adjustments related to changes in assumptions	$ 132	$ 51