Investments Investments (Summary of Unrealized Loss by 12 month Period) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investments Unrealized Loss Position [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 62,161	$ 72,970
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(83)	(144)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	1,260
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	62,161	74,230
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(83)	(149)
Corporate Debt Securities [Member]
Investments Unrealized Loss Position [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	52,055	57,898
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(81)	(131)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	1,260
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	52,055	59,158
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(81)	(136)
Debt Securities Issued By The U.S Treasury And Other U.S Government Corporations And Agencies [Member]
Investments Unrealized Loss Position [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,106	15,072
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2)	(13)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	10,106	15,072
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (2)	$ (13)