Investments - Summary of Gross Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	$ 3,223	$ 15,295
Less Than 12 Months of Unrealized Losses, Gross Unrealized Losses	(5)	(49)
12 Months or More of Unrealized Losses, Estimated Fair Value	7,104	6,981
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(43)	(1,690)
Total, Estimated Fair Value	10,327	22,276
Total, Gross Unrealized Losses	(48)	(1,739)
U.S Treasury Securities and Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	300	8,938
Less Than 12 Months of Unrealized Losses, Gross Unrealized Losses	0	(19)
12 Months or More of Unrealized Losses, Estimated Fair Value	0	0
12 Months or More of Unrealized Losses, Gross Unrealized Losses	0	0
Total, Estimated Fair Value	300	8,938
Total, Gross Unrealized Losses	0	(19)
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	2,276	5,463
Less Than 12 Months of Unrealized Losses, Gross Unrealized Losses	(2)	(10)
12 Months or More of Unrealized Losses, Estimated Fair Value	113	0
12 Months or More of Unrealized Losses, Gross Unrealized Losses	0	0
Total, Estimated Fair Value	2,389	5,463
Total, Gross Unrealized Losses	(2)	(10)
Mortgage-backed and asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	647	894
Less Than 12 Months of Unrealized Losses, Gross Unrealized Losses	(3)	(20)
12 Months or More of Unrealized Losses, Estimated Fair Value	0	353
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(4)	(42)
Total, Estimated Fair Value	647	1,247
Total, Gross Unrealized Losses	(7)	(62)
Closed-end bond funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	0	0
Less Than 12 Months of Unrealized Losses, Gross Unrealized Losses	0	0
12 Months or More of Unrealized Losses, Estimated Fair Value	6,991	6,628
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(39)	(1,648)
Total, Estimated Fair Value	6,991	6,628
Total, Gross Unrealized Losses	$ (39)	$ (1,648)