Investments (Fixed Maturities and Equity Securities Excluding Investments Classified as Trading) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	$ 2,495,928,000		$ 2,609,253,000
Available-for-sale equity securities amortized cost basis	14,000		14,000
Fair Value, Fixed maturities, available for sale	2,693,323,000		2,800,593,000
Equity securities, available for sale	17,000		17,000
Net unrealized gains on impaired securities relating to changes in value of securities subsequent to the impairment measurement date	100,000		100,000
Fixed Maturities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	2,495,928,000		2,609,253,000
Gross Unrealized Gains	210,753,000		198,461,000
Gross Unrealized Losses	13,358,000		7,121,000
Fair Value, Fixed maturities, available for sale	2,693,323,000		2,800,593,000
Other-than-temporary impairments in AOCI	62,000	[1]	85,000	[1]
Fixed Maturities [Member] | US Treasury And Government [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	6,319,000		6,324,000
Gross Unrealized Gains	79,000		22,000
Gross Unrealized Losses	0		10,000
Fair Value, Fixed maturities, available for sale	6,398,000		6,336,000
Other-than-temporary impairments in AOCI	0	[1]	0	[1]
Fixed Maturities [Member] | Obligations of U.S. states and their political subdivisions [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	20,840,000		69,486,000
Gross Unrealized Gains	1,275,000		1,323,000
Gross Unrealized Losses	0		20,000
Fair Value, Fixed maturities, available for sale	22,115,000		70,789,000
Other-than-temporary impairments in AOCI	0	[1]	0	[1]
Fixed Maturities [Member] | Foreign Government Debt Securities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	29,528,000		29,738,000
Gross Unrealized Gains	7,953,000		7,621,000
Gross Unrealized Losses	0		4,000
Fair Value, Fixed maturities, available for sale	37,481,000		37,355,000
Other-than-temporary impairments in AOCI	0	[1]	0	[1]
Fixed Maturities [Member] | Public Utilities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	200,012,000		198,277,000
Gross Unrealized Gains	30,320,000		19,909,000
Gross Unrealized Losses	1,627,000		1,593,000
Fair Value, Fixed maturities, available for sale	228,705,000		216,593,000
Other-than-temporary impairments in AOCI	0	[1]	0	[1]
Fixed Maturities [Member] | Corporate Debt Securities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	1,695,760,000		1,743,110,000
Gross Unrealized Gains	145,995,000		146,872,000
Gross Unrealized Losses	11,374,000		4,891,000
Fair Value, Fixed maturities, available for sale	1,830,381,000		1,885,091,000
Other-than-temporary impairments in AOCI	0	[1]	0	[1]
Fixed Maturities [Member] | Asset-backed Securities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	147,945,000	[2]	144,324,000	[2]
Gross Unrealized Gains	5,099,000	[2]	5,078,000	[2]
Gross Unrealized Losses	272,000	[2]	391,000	[2]
Fair Value, Fixed maturities, available for sale	152,772,000	[2]	149,011,000	[2]
Other-than-temporary impairments in AOCI	45,000	[1],[2]	39,000	[1],[2]
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	276,142,000		291,868,000
Gross Unrealized Gains	12,760,000		10,523,000
Gross Unrealized Losses	79,000		206,000
Fair Value, Fixed maturities, available for sale	288,823,000		302,185,000
Other-than-temporary impairments in AOCI	0	[1]	10,000	[1]
Fixed Maturities [Member] | Residential Mortgage Backed Securities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Fixed maturities, available-for-sale, amortized cost	119,382,000	[3]	126,126,000	[3]
Gross Unrealized Gains	7,272,000	[3]	7,113,000	[3]
Gross Unrealized Losses	6,000	[3]	6,000	[3]
Fair Value, Fixed maturities, available for sale	126,648,000	[3]	133,233,000	[3]
Other-than-temporary impairments in AOCI	17,000	[1],[3]	36,000	[1],[3]
Equity Securities Available For Sale [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Available-for-sale equity securities amortized cost basis	14,000		14,000
Gross Unrealized Gains	3,000		3,000
Gross Unrealized Losses	0		0
Equity securities, available for sale	17,000		17,000
Equity Securities Available For Sale [Member] | Public Utilities [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Available-for-sale equity securities amortized cost basis	0		0
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Equity securities, available for sale	0		0
Equity Securities Available For Sale [Member] | Mutual Fund [Member]
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Available-for-sale equity securities amortized cost basis	14,000		14,000
Gross Unrealized Gains	3,000		3,000
Gross Unrealized Losses	0		0
Equity securities, available for sale	$ 17,000		$ 17,000

[1] Represents the amount of other-than-temporary impairment losses in Accumulated Other Comprehensive Income (“AOCI”), which were not included in earnings. Amount excludes $0.1 million of net unrealized gains on impaired available-for-sale securities relating to changes in the value of such securities subsequent to the impairment measurement date.

[2] _____________ Includes credit-tranched securities collateralized by sub-prime mortgages, auto loans, credit cards, education loans, and other asset types.

[3] Includes publicly-traded agency pass-through securities and collateralized mortgage obligations.