Proceeds From Sales and Calls of Debt Securities and Associates Gains or Losses (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Available-for-sale
Sales of available-for-sale debt securities		$ 172,323	$ 4,765	$ 476,371	$ 233,446
Gross realized gains	[1]	1,347	9	4,284	15
Gross realized losses	[1]	(1,213)	(73)	(3,929)	(361)
Held-to-maturity
Proceeds from calls of debt securities		2,630	13,470	32,575	28,935
Gross realized gains	[1]	0	10	2	64
Gross realized losses	[1]	$ 0	$ (2)	$ (10)	$ (107)

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