Unobservable Input Reconciliation Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Total Gains (Losses)	$ (601)
Auction rate securities [Member]
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Fair value, measurement with unobservable inputs reconciliation, beginning	33,791
Included in earnings	1,101
Included in other comprehensive income (loss)	(332)
Purchases, sales, issuances, and settlements, net	(24,735)
Fair value, measurement with unobservable inputs reconciliation, ending	9,825
Corporate Debt [Member]
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Fair value, measurement with unobservable inputs reconciliation, beginning	6,190
Included in earnings	0
Included in other comprehensive income (loss)	0
Purchases, sales, issuances, and settlements, net	0
Fair value, measurement with unobservable inputs reconciliation, ending	6,190
Total Gains (Losses) [Member]
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Included in earnings	(269)
Included in other comprehensive income (loss)	(332)
Purchases, sales, issuances, and settlements, net