Fair Value Measurements Changes in Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs (Details) - Fair Value, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 0	$ 0	$ 0	$ 875
Sales	0		0	(770)
Unrealized adjustment to fair value	0	0	0	(105)
(Premium amortization) discount accretion		0	0	0
Balance, end of period	0	0	0	0
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	2,370	2,400	2,400
Sales	0		(2,160)	0
Unrealized adjustment to fair value	0	(2)	(242)	(32)
(Premium amortization) discount accretion		2	2	2
Balance, end of period	0	2,370	0	2,370
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	100,859	103,365	101,926	102,994
Sales	0		0	0
Unrealized adjustment to fair value	(2,869)	(67)	(3,936)	304
(Premium amortization) discount accretion		0	0	0
Balance, end of period	$ 97,990	$ 103,298	$ 97,990	$ 103,298