Fair Value Measurements Changes in Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 770	$ 865	$ 875	$ 707
Sales	(770)		(770)
Unrealized adjustment to fair value	0	10	(105)	168
(Premium amortization) discount accretion		0		0
Balance, end of period	0	875	0	875
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	2,430	3,095	2,400	3,050
Sales	0		0
Unrealized adjustment to fair value	(60)	102	(30)	144
(Premium amortization) discount accretion		3		6
Balance, end of period	2,370	3,200	2,370	3,200
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	102,810	103,049	102,994	98,668
Sales	0		0
Unrealized adjustment to fair value	555	73	371	4,454
(Premium amortization) discount accretion		0		0
Balance, end of period	$ 103,365	$ 103,122	$ 103,365	$ 103,122