Gain or Loss on Sale of Debt Securities (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale
Proceeds from Sales and Calls of Debt Securities		$ 265,587	$ 280,783	$ 212,140
Gross realized gains	[1]	443	3,369	2,459
Gross realized losses	[1]	(455)	(4,005)	(3,794)
Held-to-maturity
Proceeds from calls of debt securities		79,000	23,020	25,405
Gross realized gains	[1]	101	204	97
Gross realized losses	[1]	$ (1,202)	$ (228)	$ (225)

[1] The gain or loss on the sale or call of each debt security is determined by the specific identification method.