Investments - Additional Information (Details) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Restricted cash related to voluntary disability insurance program	$ 1,000,000	$ 900,000
Estimated fair value prested of mortgate-backed securities	1,400,000	4,600,000
Impariment charge of non-marketable strategic investments	2,300,000	1,000,000
Purchases of strategic investments	500,000	4,750,000	330,000
Other-than-temporary impairment charges	1,143,000	0	0
Unrealized gains	8,082,000	7,470,000
Unrealized Gain (Loss) on Investments		$ 7,500,000