Proceeds From Sales and Calls of Debt Securities and Associates Gains or Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Available-for-sale
Sales of available-for-sale debt securities		$ 401,701	$ 12,135	$ 878,072	$ 245,581
Gross realized gains	[1]	14,329	188	18,613	203
Gross realized losses	[1]	(518)	(37)	(4,447)	(398)
Held-to-maturity
Proceeds from calls of debt securities		16,365	28,435	48,940	57,370
Gross realized gains	[1]	0	12	2	76
Gross realized losses	[1]	$ 0	$ (530)	$ (10)	$ (637)

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