Investments (Summary Of Amortized Cost And Market Value Of Fixed Maturity Securities, By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Amortized Cost	$ 5,108,085	$ 5,235,523
Fixed maturity securities - available for sale, at market value	5,226,919	5,293,411
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Due in one year or less, Amortized Cost	353,025	385,721
Fixed maturity securities - available for sale, Due after one year through five years, Amortized Cost	2,447,447	2,387,533
Fixed maturity securities - available for sale, Due after five years through ten years, Amortized Cost	921,195	1,025,221
Fixed maturity securities - available for sale, Due after ten years, Amortized Cost	647,142	689,140
Fixed maturity securities - available for sale, Due in one year or less, Market Value	352,544	384,022
Fixed maturity securities - available for sale, Due after one year through five years, Market Value	2,468,119	2,369,917
Fixed maturity securities - available for sale, Due after five years through ten years, Market Value	943,216	1,029,077
Fixed maturity securities - available for sale, Due after ten years, Market Value	713,036	757,872
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Amortized Cost	115,357	94,470
Fixed maturity securities - available for sale, at market value	116,087	94,823
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Amortized Cost	55,527	57,027
Fixed maturity securities - available for sale, at market value	58,279	59,268
Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Amortized Cost	568,152	596,140
Fixed maturity securities - available for sale, at market value	575,361	598,117
Non-Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities - available for sale, Amortized Cost	240	271
Fixed maturity securities - available for sale, at market value	$ 277	$ 315

Amount of debt securities categorized neither as held-to-maturity nor trading, held at market value.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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