Investments (Other Than Temporary Impairment by Asset Type) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) Securities	Dec. 31, 2014 USD ($) Securities	Dec. 31, 2013 USD ($) Securities
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities									14		10
Total OTTI losses									$ (25,547)	$ 0	$ (4,964)
Portion of OTTI losses recognized in (from) other comprehensive income									6,011	(2,627)	(1,270)
Net OTTI losses recognized in operations	$ (13,347)	$ (5,229)	$ (828)	$ (132)	$ (564)	$ (564)	$ (594)	$ (905)	$ (19,536)	$ (2,627)	$ (6,234)
Corporate Securities [Member] | Industrial [Member]
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities									2		1
Total OTTI losses									$ (15,414)		$ (1,761)
Portion of OTTI losses recognized in (from) other comprehensive income									2,975		0
Net OTTI losses recognized in operations									$ (12,439)		$ (1,761)
Residential Mortgage Backed Securities [Member]
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities									11	7	6
Total OTTI losses									$ (133)	$ 0	$ 0
Portion of OTTI losses recognized in (from) other comprehensive income									(2,089)	(2,627)	(1,270)
Net OTTI losses recognized in operations									$ (2,222)	$ (2,627)	$ (1,270)
Other Asset Backed Securities [Member]
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities									1
Total OTTI losses									$ (10,000)
Portion of OTTI losses recognized in (from) other comprehensive income									5,125
Net OTTI losses recognized in operations									$ (4,875)
United States Government Sponsored Agencies [Member]
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities											2
Total OTTI losses											$ (2,775)
Portion of OTTI losses recognized in (from) other comprehensive income											0
Net OTTI losses recognized in operations											$ (2,775)
Equity Securities [Member] | Industrial [Member]
Gain (Loss) on Investments [Line Items]
Other than temporary impairment, number of securities | Securities											1
Total OTTI losses											$ (428)
Portion of OTTI losses recognized in (from) other comprehensive income											0
Net OTTI losses recognized in operations											$ (428)