Financial Instruments And Investments (Contractual Year For Maturity Of Available-For-Sale Securities ) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Due For, Mortgaged Backed Securities	10 years
Municipal Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	35,333
2013	1,787
2014 through 2017	12,323
2018 through 2022	16,394
2023 and Beyond	4,829
Corporate Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	12,831
2013	0
2014 through 2017	4,653
2018 through 2022	4,211
2023 and Beyond	3,967
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	24,305
2013	1,293
2014 through 2017	9,109
2018 through 2022	9,659
2023 and Beyond	4,244
Maximum
Schedule of Available-for-sale Securities [Line Items]
Debt Instrument, Expected Weighted Average Maturity Year	7 years
Minimum
Schedule of Available-for-sale Securities [Line Items]
Debt Instrument, Expected Weighted Average Maturity Year	3 years

Amount of debt securities categorized neither as held-to-maturity nor trading.

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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