Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	$ 239,450	$ 322,351
Less than 12 months Gross Unrealized Losses	12,368	5,969
Twelve months or more Fair Value	38,189	58,991
Twelve months or more Gross Unrealized Losses	990	1,152
Total Fair Value	277,639	381,342
Total Gross Unrealized Losses	13,358	7,121
US Treasury And Government [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	0	2,676
Less than 12 months Gross Unrealized Losses	0	10
Twelve months or more Fair Value	0	0
Twelve months or more Gross Unrealized Losses	0	0
Total Fair Value	0	2,676
Total Gross Unrealized Losses	0	10
Obligations of U.S. states and their political subdivisions [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	0	0
Less than 12 months Gross Unrealized Losses	0	0
Twelve months or more Fair Value	0	7,305
Twelve months or more Gross Unrealized Losses	0	20
Total Fair Value	0	7,305
Total Gross Unrealized Losses	0	20
Foreign Government Debt Securities [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	0
Less than 12 months Gross Unrealized Losses	0
Twelve months or more Fair Value	0
Twelve months or more Gross Unrealized Losses	0
Total Fair Value	0
Total Gross Unrealized Losses	0
Corporate Debt Securities [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	209,949	260,414
Less than 12 months Gross Unrealized Losses	10,994	4,462
Twelve months or more Fair Value	3,321	9,403
Twelve months or more Gross Unrealized Losses	380	429
Total Fair Value	213,270	269,817
Total Gross Unrealized Losses	11,374	4,891
Asset-backed Securities [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	10,873	31,756
Less than 12 months Gross Unrealized Losses	7	58
Twelve months or more Fair Value	32,753	32,732
Twelve months or more Gross Unrealized Losses	265	333
Total Fair Value	43,626	64,488
Total Gross Unrealized Losses	272	391
Commercial Mortgage Backed Securities [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	4,136	4,309
Less than 12 months Gross Unrealized Losses	79	108
Twelve months or more Fair Value	14	7,377
Twelve months or more Gross Unrealized Losses	0	98
Total Fair Value	4,150	11,686
Total Gross Unrealized Losses	79	206
Residential Mortgage Backed Securities [Member]
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	318	342
Less than 12 months Gross Unrealized Losses	6	6
Twelve months or more Fair Value	0	0
Twelve months or more Gross Unrealized Losses	0	0
Total Fair Value	318	342
Total Gross Unrealized Losses	6	6
PublicUtilityBondsMember
Duration Of Unrealized Losses On Fixed Maturities Investments [Line Items]
Less than twelve months Fair Value	14,174	18,222
Less than 12 months Gross Unrealized Losses	1,282	1,321
Twelve months or more Fair Value	2,101	2,174
Twelve months or more Gross Unrealized Losses	345	272
Total Fair Value	16,275	20,396
Total Gross Unrealized Losses	$ 1,627	$ 1,593