Comprehensive Income (Schedule of Changes in the Components of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2013
Changes in the components of AOCI
Balance at March 31, 2013	$ 6,935
Other comprehensive loss before reclassifications	(8,070)
Amounts reclassified from accumulated other comprehensive income (loss)	(1,390)
Net other comprehensive loss	(9,460)
Balance at September 30, 2013	(2,525)
Unrealized holding gains (losses) on available-for-sale securities
Changes in the components of AOCI
Balance at March 31, 2013	5,444
Other comprehensive loss before reclassifications	(8,070)
Amounts reclassified from accumulated other comprehensive income (loss)	(1,390)
Net other comprehensive loss	(9,460)
Balance at September 30, 2013	(4,016)
Minimum pension liability
Changes in the components of AOCI
Balance at March 31, 2013	52
Other comprehensive loss before reclassifications	0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net other comprehensive loss	0
Balance at September 30, 2013	52
Foreign Currency
Changes in the components of AOCI
Balance at March 31, 2013	1,439
Other comprehensive loss before reclassifications	0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net other comprehensive loss	0
Balance at September 30, 2013	$ 1,439