Investments (Fixed Maturities and Equity Securities Excluding Investments Classified as Trading) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	$ 2,391,318	$ 2,609,253
Amortized Cost	14	14
Fair Value	2,533,299	2,800,593
Fair Value	17	17
Net unrealized gains on impaired securities relating to changes in value of securities subsequent to the impairment measurement date	100	100
Fixed maturities, available-for-sale
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	2,391,318	2,609,253
Gross Unrealized Gains	156,906	198,461
Gross Unrealized Losses	14,925	7,121
Fair Value	2,533,299	2,800,593
Other-than-temporary Impairments in AOCI	(45)	(85)
Fixed maturities, available-for-sale | U.S. Treasury securities and obligations of U.S. government authorities and agencies
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	6,313	6,324
Gross Unrealized Gains	58	22
Gross Unrealized Losses	0	10
Fair Value	6,371	6,336
Other-than-temporary Impairments in AOCI	0	0
Fixed maturities, available-for-sale | Obligations of U.S. states and their political subdivisions
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	20,496	69,486
Gross Unrealized Gains	530	1,323
Gross Unrealized Losses	579	20
Fair Value	20,447	70,789
Other-than-temporary Impairments in AOCI	0	0
Fixed maturities, available-for-sale | Foreign government bonds
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	36,959	29,738
Gross Unrealized Gains	6,497	7,621
Gross Unrealized Losses	5	4
Fair Value	43,451	37,355
Other-than-temporary Impairments in AOCI	0	0
Fixed maturities, available-for-sale | Public utilities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	199,629	198,277
Gross Unrealized Gains	18,967	19,909
Gross Unrealized Losses	2,742	1,593
Fair Value	215,854	216,593
Other-than-temporary Impairments in AOCI	0	0
Fixed maturities, available-for-sale | All other corporate securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	1,616,585	1,743,110
Gross Unrealized Gains	113,739	146,872
Gross Unrealized Losses	11,214	4,891
Fair Value	1,719,110	1,885,091
Other-than-temporary Impairments in AOCI	0	0
Fixed maturities, available-for-sale | Asset-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	146,558	144,324
Gross Unrealized Gains	4,667	5,078
Gross Unrealized Losses	194	391
Fair Value	151,031	149,011
Other-than-temporary Impairments in AOCI	(37)	(39)
Fixed maturities, available-for-sale | Commercial mortgage-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	253,314	291,868
Gross Unrealized Gains	6,775	10,523
Gross Unrealized Losses	191	206
Fair Value	259,898	302,185
Other-than-temporary Impairments in AOCI	0	(10)
Fixed maturities, available-for-sale | Residential mortgage-backed securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	111,464	126,126
Gross Unrealized Gains	5,673	7,113
Gross Unrealized Losses	0	6
Fair Value	117,137	133,233
Other-than-temporary Impairments in AOCI	(8)	(36)
Equity securities, available-for-sale
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	14	14
Gross Unrealized Gains	3	3
Gross Unrealized Losses	0	0
Fair Value	17	17
Equity securities, available-for-sale | Public utilities
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	0
Equity securities, available-for-sale | Mutual funds
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Amortized Cost	14	14
Gross Unrealized Gains	3	3
Gross Unrealized Losses	0	0
Fair Value	$ 17	$ 17