Investments (Tables)

6 Months Ended

Sep. 30, 2016

Investments [Abstract]

Summary of available-for-sale securities

The following is a summary of available-for-sale securities at September 30, 2016 (amounts in thousands):

	Available-for-sale Securities
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Marketable equity securities	$	2,140	$	—	$	(1,292	)	$	848

The following is a summary of available-for-sale securities at March 31, 2016 (amounts in thousands):

	Available-for-sale Securities
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Government agency bonds	$	468,290	$	439	$	(99	)	$	468,630
Corporate bonds and debt	1,000		—		—			1,000
Marketable equity securities	2,195		8		—			2,203
	$	471,485	$	447	$	(99	)	$	471,833

Summary of available-for-sale securities in a continuous unrealized loss position

The following tables show all investments in an unrealized loss position for which an other-than-temporary impairment has not been recognized and the related gross unrealized losses and fair value, aggregated by investment category and the length of time that the individual securities have been in a continuous unrealized loss position (amounts in thousands):

	September 30, 2016
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Marketable equity securities	$	848	$	(1,292	)	$	—	$	—	$	848	$	(1,292	)

	March 31, 2016
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Government agency bonds	$	148,562	$	(99	)	$	—	$	—	$	148,562	$	(99	)
Corporate bonds and debt	—		—			1,000		—		1,000		—
	$	148,562	$	(99	)	$	1,000	$	—	$	149,562	$	(99	)