INVESTMENTS: (Tables)

3 Months Ended

Mar. 31, 2015

INVESTMENTS:

Schedule of cash, cash equivalents and short-term investments

	March 31, 2015
	Amortized Cost			Unrealized Gains		Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash	$	58,787		$	—	$	—		$	58,787
Money market funds	869			—		—			869
Certificates of deposit	91,370			9		(2		)	91,377
U.S. Government and agency securities	102,465			78		(12		)	102,531
Commercial paper	17,947			18		—			17,965
Corporate bonds	120,341			117		(89		)	120,369
Municipal bonds	25,185			13		(37		)	25,161
Foreign government bonds	12,083			3		(21		)	12,065
Total	$	429,047		$	238	$	(161	)	$	429,124
Less amounts classified as cash and cash equivalents	(61,656		)	—		—			(61,656		)
	$	367,391		$	238	$	(161	)	$	367,468

	December 31, 2014
	Amortized  Cost			Unrealized  Gains		Unrealized  Losses			Estimated  Fair Value
	(in thousands)
Cash	$	46,900		$	—	$	—		$	46,900
Money market funds	4,426			—		—			4,426
Certificates of deposit	80,304			1		(30		)	80,275
U.S. Government and agency securities	99,236			9		(131		)	99,114
Commercial paper	23,017			3		(1		)	23,019
Corporate bonds	112,033			16		(313		)	111,736
Municipal bonds	13,151			—		(47		)	13,104
Foreign government bonds	6,809			—		(19		)	6,790
Total	$	385,876		$	29	$	(541	)	$	385,364
Less amounts classified as cash and cash equivalents	(51,326		)	—		—			(51,326		)
	$	334,550		$	29	$	(541	)	$	334,038

Schedule of contractual maturities of short-term investments

	March 31, 2015				December 31, 2014
	Amortized  Cost		Estimated Fair  Value		Amortized  Cost		Estimated Fair  Value
	(in thousands)
Due in less than one year	$	126,109	$	126,123	$	129,150	$	129,155
Due in one to three years	241,282		241,345		205,400		204,883
	$	367,391	$	367,468	$	334,550	$	334,038