Investments (Tables)

3 Months Ended

Mar. 31, 2014

Investment in Marketable Securities [Abstract]

Investments

	At March 31, 2014
	Cost		Gross Unrealized Losses			Gross Unrealized Gains		Estimated Fair Value
Short-term investments	$	45,724	$	(96	)	$	—	$	45,628
Marketable equity securities	15,484		(724		)	886		15,646

	At December 31, 2013
	Cost		Gross Unrealized Losses			Gross Unrealized Gains		Estimated Fair Value
Marketable equity securities	$	17,649	$	(3,300	)	$	172	$	14,521

Gross unrealized losses on investment securities

The following table summarizes the gross unrealized losses on investment securities for which other-than-temporary impairments have not been recognized and the fair values of those securities, aggregated by the length of time the individual securities have been in a continuous unrealized loss position, at March 31, 2014 (in thousands):

	Less than twelve months					Twelve months or more					Total
	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
Short-term investments	$	(96	)	$	45,628	$	—		$	—	$	(96	)	$	45,628
Marketable equity securities	$	—		$	—	$	(724	)	$	1,320	$	(724	)	$	1,320