Investment Securities Other Investments (Details) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Other Investments Carrying Value [Line Items]
Other investment securities	$ 40,715,000				$ 40,715,000		$ 42,730,000
Proceeds from Sale of Federal Home Loan Bank Stock	2,100,000	$ 4,500,000	$ 700,000
Payments to Acquire Federal Home Loan Bank Stock	0	$ 0	$ 5,000,000.0
Trading Securities, Change in Unrealized Holding Gain (Loss)	1,000,000			$ 19,000,000	15,000,000	$ 828,000,000
Gain (Loss) on Sale of Equity Investments						$ 787,000
Securities of a single issuer, other than US Treasury, government agencies and US government sponsored agencies exceeding 10% of Stockholders' Equity	0				0
Reported Value Measurement [Member]
Other Investments Carrying Value [Line Items]
Federal Home Loan Bank Stock	25,022,000				25,022,000		27,235,000
Federal Reserve Bank ("FRB") stock	13,311,000				13,311,000		13,310,000
Other investment securities	40,409,000				40,409,000		42,409,000
Reported Value Measurement [Member] | Other Security Investments [Member]
Other Investments Carrying Value [Line Items]
Other investment securities	365,000				365,000		365,000	$ 0
Other | Reported Value Measurement [Member]
Other Investments Carrying Value [Line Items]
Other investment securities	365,000				365,000		365,000
Nonqualified Plan [Member] | Reported Value Measurement [Member]
Other Investments Carrying Value [Line Items]
Other investment securities	1,711,000				1,711,000		1,499,000
Equity investment securities (a)
Other Investments Carrying Value [Line Items]
Other investment securities	$ 306,000				$ 306,000		$ 321,000