Certain Financial Statement Information Gross Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014
Schedule of Gross Unrealized Losses
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	$ 3,347	$ 6,242
Less than 12 Months of Unrealized Losses, Gross Unrealized Losses	(5)	(351)
12 Months or More of Unrealized Losses, Estimated Fair Value	5,566	405
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(130)	(69)
Total, Estimated Fair Value	8,913	6,647
Total Gross Unrealized Losses	(135)	(420)
Corporate bonds [Member]
Schedule of Gross Unrealized Losses
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	3,132	992
Less than 12 Months of Unrealized Losses, Gross Unrealized Losses	(4)	(2)
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	3,132	992
Total Gross Unrealized Losses	(4)	(2)
Mortgage-backed and asset-backed securities [Member]
Schedule of Gross Unrealized Losses
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	173	431
Less than 12 Months of Unrealized Losses, Gross Unrealized Losses	0	(16)
12 Months or More of Unrealized Losses, Estimated Fair Value	116	0
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(2)	0
Total, Estimated Fair Value	289	431
Total Gross Unrealized Losses	(2)	(16)
Closed-end bond funds [Member]
Schedule of Gross Unrealized Losses
Less Than 12 Months of Unrealized Losses, Estimated Fair Value	42	4,819
Less than 12 Months of Unrealized Losses, Gross Unrealized Losses	(1)	(333)
12 Months or More of Unrealized Losses, Estimated Fair Value	5,450	405
12 Months or More of Unrealized Losses, Gross Unrealized Losses	(128)	(69)
Total, Estimated Fair Value	5,492	5,224
Total Gross Unrealized Losses	$ (129)	$ (402)