Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Amounts Reclassified from AOCI [Abstract]
Securities gains	$ (2)	$ 48	$ (288)	$ 58
Tax expense	3,044	5,811	8,425	15,010
Net income	16,106	13,763	43,519	36,581
Unrealized Gains on AFS Securities [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Amounts Reclassified from AOCI [Abstract]
Securities gains	(2)	48	149	58
Tax expense	0	17	32	20
Net income	$ (2)	$ 31	$ 117	$ 38