Investments Investments (Summary of Unrealized Loss by 12 month Period) (Details) - USD ($) $ in Thousands	Sep. 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	$ 46,094	$ 72,970
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(56)	(144)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,650	1,260
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1)	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	47,744	74,230
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(57)	(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	41,966	57,898
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(55)	(131)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,000	1,260
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1)	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	42,966	59,158
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(56)	(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	3,248	15,072
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1)	(13)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	650	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	3,898	15,072
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(1)	$ (13)
Debt Securities Issued By States Of The United States And Political Subdivisions Of The States [Member]
Investments Unrealized Loss Position [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	880
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	880
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 0