Securities, Gains and Losses Realized on Sale of Securities Available for Sale (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017
Gain and losses realized on sale of securities available for sale [Abstract]
Proceeds	$ 31,445		$ 9,594	[1]
Realized gains	81	[2]	125
Realized losses	126		0
Sale of securities available for sale not yet settled	0		760
Trading securities, realized losses	(170)		$ (63)
VISA Class B Shares [Member]
Gain and losses realized on sale of securities available for sale [Abstract]
Realized gains	$ 144
Number securities sold (in shares)	1,000

[1] 2017 includes $0.760 million for trades that did not settle until after September 30, 2017.

[2] 2018 excludes a $0.144 million gain on the sale of 1,000 VISA Class B shares.