Marketable Securities (Tables)

3 Months Ended

Jun. 30, 2013

Investments Debt And Equity Securities [Abstract]

Schedule of Available-for-Sale Securities

The Company’s portfolio of available-for-sale marketable securities consists of the following:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
June 30, 2013
U.S. government and agency securities	$	92,577	$	130	$	(249	)	$	92,458
Corporate debt obligations		151,342		950		(648	)		151,644
Mortgage-backed securities		53,212		185		(466	)		52,931
Municipal bonds		39,883		17		(211	)		39,689
Other debt securities		600		—		(5	)		595
	$	337,614	$	1,282	$	(1,579	)	$	337,317
March 31, 2013
U.S. government and agency securities	$	113,033	$	327	$	(1	)	$	113,359
Corporate debt obligations		153,460		1,429		(30	)		154,859
Mortgage-backed securities		50,852		473		(44	)		51,281
Municipal bonds		39,661		211		—			39,872
Other debt securities		602		1		—			603
	$	357,608	$	2,441	$	(75	)	$	359,974

Schedule of Amortized Cost and Estimated Fair Value of Debt Securities

The amortized cost and estimated fair value of debt securities as of June 30, 2013, by contractual maturity, are presented below. Expected maturities will differ from contractual maturities because the issuers of securities may have the right to repay obligations without prepayment penalties. Certain debt instruments, although possessing a contractual maturity greater than one year, are classified as short-term marketable securities based on their ability to be traded on active markets and availability for current operations.

	Amortized Cost		Estimated Fair Value
	(In thousands)
Due in one year or less	$	91,669	$	91,825
Due after one year through three years		146,200		146,284
Due after three years through five years		58,173		57,246
Due after five years		41,572		41,962
	$	337,614	$	337,317

Schedule of Unrealized Losses by Investment Category

The following table presents the Company’s marketable securities with unrealized losses by investment category and length of time that individual securities have been in a continuous unrealized loss position as of June 30, 2013 and March 31, 2013.

	Less Than 12 Months					12 Months or Greater					Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
June 30, 2013
U.S. government and agency securities	$	39,004	$	(249	)	$	—	$	—		$	39,004	$	(249	)
Corporate debt obligations		70,496		(648	)		—		—			70,496		(648	)
Mortgage-backed securities		33,607		(463	)		373		(3	)		33,980		(466	)
Municipal bonds		28,653		(211	)		—		—			28,653		(211	)
Other debt securities		595		(5	)		—		—			595		(5	)
	$	172,355	$	(1,576	)	$	373	$	(3	)	$	172,728	$	(1,579	)
March 31, 2013
U.S. government and agency securities	$	4,502	$	(1	)	$	—	$	—		$	4,502	$	(1	)
Corporate debt obligations		24,203		(30	)		—		—			24,203		(30	)
Mortgage-backed securities		10,048		(44	)		—		—			10,048		(44	)
	$	38,753	$	(75	)	$	—	$	—		$	38,753	$	(75	)