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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	$ 770	$ 0	$ 875
Sales	0	(770)	0	(770)
Unrealized adjustment to fair value	0	0	0	(105)
(Premium amortization) discount accretion			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	2,160	2,430	2,400	2,400
Sales	(2,160)	0	(2,160)	0
Unrealized adjustment to fair value	0	(60)	(242)	(30)
(Premium amortization) discount accretion			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	93,666	102,810	101,926	102,994
Sales	0	0	0	0
Unrealized adjustment to fair value	7,193	555	(1,067)	371
(Premium amortization) discount accretion			0
Balance, end of period	$ 100,859	$ 103,365	$ 100,859	$ 103,365