Gain or Loss on Sale of Debt Securities (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale
Proceeds from Sales and Calls of Debt Securities		$ 928,710	$ 265,587	$ 280,783
Gross realized gains	[1]	18,936	443	3,369
Gross realized losses	[1]	(4,513)	(455)	(4,005)
Held-to-maturity
Proceeds from calls of debt securities		58,750	79,000	23,020
Gross realized gains	[1]	2	101	204
Gross realized losses	[1]	$ (10)	$ (1,202)	$ (228)

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