Available For Sale Securities (Amortized Cost And Estimated Fair Value Of Investments Classified As Available For Sale By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Available For Sale Securities [Abstract]
Due within one year, Amortized Cost	$ 879,125
Due after one year through five years, Amortized Cost	18,214
Fixed maturities investments excluding mortgage-backed and asset-backed securities, Amortized Cost	897,339
Mortgage-backed and asset-backed securities, Amortized Cost	870,137
Total fixed maturities investments, Amortized Cost	1,767,476
Due within one year, Estimated Fair Value	879,314
Due after one year through five years, Estimated Fair Value	18,140
Fixed maturities investments excluding mortgage-backed and asset-backed securities, Estimated Fair Value	897,454
Mortgage-backed and asset-backed securities, Estimated Fair Value	880,217
Total fixed maturities investments, Estimated Fair Value	$ 1,777,671