Cash and Cash Equivalents and Marketable Securities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Mar. 31, 2013	Mar. 31, 2012
Cash, Cash Equivalents and Marketable Securities [Line Items]
Short-term marketable securities, current		$ 37,338	$ 79,617
Long-term marketable securities		16,823	16,644
Reduction in the valuation reserve reflecting redemptions at par	190
Reduction in the valuation reserve reflecting redemptions at par, net of tax	117
Auction Rate Securities
Cash, Cash Equivalents and Marketable Securities [Line Items]
Auction rate securities redemption at par by issuers	19,300
Short-term marketable securities, current			17,600
Long-term marketable securities			$ 1,700