Loans, Changes in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in the Allowance for Unfunded Commitments
Balance at beginning of period	$ 24,000
Balance at end of period	24,000	$ 24,000
Allowance for Unfunded Commitments
Change in the Allowance for Unfunded Commitments
Balance at beginning of period	24,400	25,400	$ 24,400
Provision for unfunded commitments	(2,500)	(1,000)	1,000
Amount recorded at acquisition	2,436	0	0
Balance at end of period	$ 24,336	$ 24,400	$ 25,400