Investment Securities Gross Unrealized Losses - AFS (Details) $ in Thousands	Sep. 30, 2020 USD ($) securities	Dec. 31, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 77,316	$ 150,616
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(1,423)	(1,142)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	14,581	56,826
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(414)	(1,148)
Available-for-sale securities, total, continuous unrealized loss position, fair value	91,897	207,442
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	(1,837)	(2,290)
State and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	30,977
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(492)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	0
Available-for-sale securities, total, continuous unrealized loss position, fair value	30,977
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (492)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	11
Collateralized mortgage obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value		54,521
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)		(335)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value		35,546
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)		(294)
Available-for-sale securities, total, continuous unrealized loss position, fair value		90,067
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)		(629)
Mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 14,432	45,132
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(24)	(174)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	0	4,687
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	0	(59)
Available-for-sale securities, total, continuous unrealized loss position, fair value	14,432	49,819
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (24)	(233)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	1
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value		3,641
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)		(4)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value		7,075
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)		(13)
Available-for-sale securities, total, continuous unrealized loss position, fair value		10,716
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)		(17)
Collateralized loan obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 31,907	42,823
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(907)	(128)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	14,581	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(414)	0
Available-for-sale securities, total, continuous unrealized loss position, fair value	46,488	42,823
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (1,321)	(128)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	8
Corporate notes and other investments
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value		4,499
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)		(501)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value		9,518
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)		(782)
Available-for-sale securities, total, continuous unrealized loss position, fair value		14,017
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)		$ (1,283)