Business Combinations and Asset Acquisitions (Summary of FDIC Indemnification Asset) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period		$ 16,701
Reductions from reimbursable expenses		(291)
Amortization		1,044
Changes in expected reimbursements from the FDIC for changes in expected credit losses	$ (4,900)	(1,658)
Resolution through payments paid to the FDIC and termination of loss share agreements		(15,796)
Balance at end of period		$ 0