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
	Mar. 31, 2020	Mar. 31, 2019
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 0	$ 875
Unrealized adjustment to fair value	0	(105)
(Premium amortization) discount accretion	0
Balance, end of period	0	770
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	2,400	2,400
Unrealized adjustment to fair value	(242)	30
(Premium amortization) discount accretion	2
Balance, end of period	2,160	2,430
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	101,926	102,994
Unrealized adjustment to fair value	(8,260)	(184)
(Premium amortization) discount accretion	0
Balance, end of period	$ 93,666	$ 102,810