Financial Instruments And Investments (Contractual Year For Maturity Of Available-For-Sale Securities ) (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Federal Agency Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Total	$ 27,207
2018	0
2019 through 2022	8
2023 through 2027	228
2028 and Beyond	26,971
U.S. Government Bonds
Debt Securities, Available-for-sale [Line Items]
Total	48,921
2018	1,228
2019 through 2022	27,157
2023 through 2027	11,148
2028 and Beyond	9,388
Municipal Obligations
Debt Securities, Available-for-sale [Line Items]
Total	14,463
2018	104
2019 through 2022	5,498
2023 through 2027	5,716
2028 and Beyond	3,145
Corporate Obligations
Debt Securities, Available-for-sale [Line Items]
Total	39,999
2018	0
2019 through 2022	17,764
2023 through 2027	9,968
2028 and Beyond	$ 12,267

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