Financial Instruments And Investments (Marketable Securities Fair Value And Unrealized Losses) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) securities		Dec. 31, 2014 USD ($) securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	$ 73,859	[1]	$ 34,651	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(2,401)	[1]	(1,141)	[2]
Marketable Securities Fair Value 12 Months or Longer	25,080	[1]	33,474	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(1,344)	[1]	(1,151)	[2]
Marketable Securities Fair Value, Total	98,939	[1]	68,125	[2]
Marketable Securities Unrealized Losses, Total	$ (3,745)	[1]	$ (2,292)	[2]
Number of securities | securities	133		106
Debt Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	$ 47,821	[1]	$ 10,440	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(1,289)	[1]	(91)	[2]
Marketable Securities Fair Value 12 Months or Longer	25,080	[1]	33,474	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(1,344)	[1]	(1,151)	[2]
Marketable Securities Fair Value, Total	72,901	[1]	43,914	[2]
Marketable Securities Unrealized Losses, Total	(2,633)	[1]	(1,242)	[2]
Collateralized Mortgage Backed Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	9,383	[1]	0	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(97)	[1]	0	[2]
Marketable Securities Fair Value 12 Months or Longer	1,113	[1]	2,383	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(47)	[1]	(57)	[2]
Marketable Securities Fair Value, Total	10,496	[1]	2,383	[2]
Marketable Securities Unrealized Losses, Total	(144)	[1]	(57)	[2]
U.S. Government Bonds
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	24,094	[1]	1,552	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(310)	[1]	(2)	[2]
Marketable Securities Fair Value 12 Months or Longer	14,272	[1]	20,060	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(623)	[1]	(573)	[2]
Marketable Securities Fair Value, Total	38,366	[1]	21,612	[2]
Marketable Securities Unrealized Losses, Total	(933)	[1]	(575)	[2]
Municipal Bonds
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	8,286	[1]	6,433	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(160)	[1]	(65)	[2]
Marketable Securities Fair Value 12 Months or Longer	7,388	[1]	8,570	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(446)	[1]	(410)	[2]
Marketable Securities Fair Value, Total	15,674	[1]	15,003	[2]
Marketable Securities Unrealized Losses, Total	(606)	[1]	(475)	[2]
Corporate Debt Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	6,058	[1]	2,455	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(722)	[1]	(24)	[2]
Marketable Securities Fair Value 12 Months or Longer	2,307	[1]	2,461	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	(228)	[1]	(111)	[2]
Marketable Securities Fair Value, Total	8,365	[1]	4,916	[2]
Marketable Securities Unrealized Losses, Total	(950)	[1]	(135)	[2]
Equity Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	3,584	[1]	1,475	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(344)	[1]	(229)	[2]
Marketable Securities Fair Value 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Fair Value, Total	3,584	[1]	1,475	[2]
Marketable Securities Unrealized Losses, Total	(344)	[1]	(229)	[2]
Institutional Funds-International Equity
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value, Less than 12 Months	22,454	[1]	22,736	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	(768)	[1]	(821)	[2]
Marketable Securities Fair Value 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Fair Value, Total	22,454	[1]	22,736	[2]
Marketable Securities Unrealized Losses, Total	$ (768)	[1]	$ (821)	[2]

[1] Includes approximately 133 securities.

[2] Includes approximately 106 securities.