Unobservable Input Reconciliation Assets (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2016 USD ($)
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings and Gain (Loss) Included in Other Comprehensive Income (Loss)	$ (1,215)
Auction rate securities [Member]
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Fair value, measurement with unobservable inputs reconciliation, beginning	9,825
Included in earnings	2,780
Purchases, sales, issuances, and settlements, net	(12,605)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0
Fair value, measurement with unobservable inputs reconciliation, ending	0
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	(3,995)
Purchases, sales, issuances, and settlements, net	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(2,195)
Fair value, measurement with unobservable inputs reconciliation, ending	0
Total Gains (Losses) [Member]
Fair value, assets measured on recurring basis, unobservable input reconciliation [Line Items]
Included in earnings	$ (1,215)