Investments Classified by Maturity Date (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis, Percent of Total	8.30%
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent of Total	8.30%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis, Percent of Total	51.80%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value, Percent of Total	52.00%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis, Percent of Total	26.30%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent of Total	26.10%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis, Percent of Total	13.60%
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value, Percent of Total	13.60%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Percent of Total	100.00%
Available-for-sale Securities, Fair Value Disclosure	$ 245,821	$ 152,180
Available-for-sale Securities, Fair Value Disclosure, Percent of Total	100.00%
Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	19,281
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	19,308
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	121,131
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	121,246
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	61,502
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	60,933
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	31,781
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	31,857
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	233,695
Available-for-sale Securities, Fair Value Disclosure	$ 233,344	$ 149,157