Investment Securities Gross Unrealized Losses - AFS (Details) $ in Thousands	Sep. 30, 2019 USD ($) securities	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 89,310	$ 90,592
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(299)	(1,216)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	62,292	316,878
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(1,166)	(9,897)
Available-for-sale securities, total, continuous unrealized loss position, fair value	151,602	407,470
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (1,465)	(11,113)
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		21,264
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)		(221)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value		102,853
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)		(3,072)
Available-for-sale securities, total, continuous unrealized loss position, fair value		124,117
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)		(3,293)
Collateralized mortgage obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sales securities in unrealized loss positions, qualitative disclosure, number of positions | securities	27
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 43,662	32,230
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(168)	(250)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	40,628	124,775
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(301)	(4,138)
Available-for-sale securities, total, continuous unrealized loss position, fair value	84,290	157,005
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (469)	(4,388)
Mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sales securities in unrealized loss positions, qualitative disclosure, number of positions | securities	7
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 14,916	10,960
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(55)	(103)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	4,821	51,823
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(68)	(1,332)
Available-for-sale securities, total, continuous unrealized loss position, fair value	19,737	62,783
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (123)	(1,435)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sales securities in unrealized loss positions, qualitative disclosure, number of positions | securities	3
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 3,842	6,668
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(6)	(31)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	7,618	16,486
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(22)	(144)
Available-for-sale securities, total, continuous unrealized loss position, fair value	11,460	23,154
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (28)	(175)
Collateralized loan obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sales securities in unrealized loss positions, qualitative disclosure, number of positions | securities	4
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 26,890
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	(70)
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	26,890
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (70)
Trust preferred security [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value		0
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)		0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value		1,900
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)		(253)
Available-for-sale securities, total, continuous unrealized loss position, fair value		1,900
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)		(253)
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Available-for-sales securities in unrealized loss positions, qualitative disclosure, number of positions | securities	3
Available-for-sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 0	19,470
Available-for-sale securities, continuous unrealized loss position, less than 12 months, gross unrealized (losses)	0	(611)
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, fair value	9,225	19,041
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, gross unrealized (losses)	(775)	(958)
Available-for-sale securities, total, continuous unrealized loss position, fair value	9,225	38,511
Available-for-sale securities, continuous unrealized loss position, gross unrealized (losses)	$ (775)	$ (1,569)