Investments Classified by Maturity Date (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis, Percent of Total	20.30%
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent of Total	19.80%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis, Percent of Total	44.50%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value, Percent of Total	43.80%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis, Percent of Total	18.10%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent of Total	18.80%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis, Percent of Total	17.10%
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value, Percent of Total	17.60%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Percent of Total	100.00%
Available-for-sale Securities, Fair Value Disclosure	$ 193,566	$ 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	37,583
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	37,450
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	82,382
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	82,919
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	33,534
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	35,533
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	31,674
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	33,365
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	185,173
Available-for-sale Securities, Fair Value Disclosure	$ 189,267	$ 149,157