Available For Sale Securities (Amortized Cost And Estimated Fair Value Of Investments Classified As Available For Sale By Contractual Maturity) (Details) $ in Thousands	Mar. 31, 2016 USD ($)
Investments [Abstract]
Due within one year, Amortized Cost	$ 306,437
Due after one year through five years, Amortized Cost	509
Due after five years through ten years, Amortized Cost	0
Due after ten years, Amortized Cost	0
Fixed maturities investments excluding mortgage-backed and asset-backed securities, Amortized Cost	306,946
Mortgage-backed and asset-backed securities, Amortized Cost	20,094
Total fixed maturities investments, Amortized Cost	327,040
Due within one year, Estimated Fair Value	306,460
Due after one year through five years, Estimated Fair Value	507
Due after five years through ten years, Estimated Fair Value	0
Due after ten years, Estimated Fair Value	0
Fixed maturities investments excluding mortgage-backed and asset-backed securities, Estimated Fair Value	306,967
Mortgage-backed and asset-backed securities, Estimated Fair Value	19,889
Total fixed maturities investments, Estimated Fair Value	$ 326,856