MARKETABLE SECURITIES

3 Months Ended

Mar. 31, 2015

MARKETABLE SECURITIES

4. MARKETABLE SECURITIES

The following tables summarize the fair value, accumulated other comprehensive income and intraperiod tax allocation regarding our investment in Regulus available-for-sale marketable securities at March 31, 2015 and 2014, and for the activity recorded for the three months ended March 31, 2015 and 2014, in thousands:

Description	At December 31, 2014			Sales of Regulus Shares During Three Months Ended March 31, 2015		All Other Activity During Three Months Ended March 31, 2015			Balance at March 31, 2015
Carrying value	$	11,935		$	—	$	—		$	11,935
Accumulated other comprehensive income, before tax		82,648			—		5,307			87,955
Investment in equity securities of Regulus, as reported	$	94,583		$	—	$	5,307		$	99,890
Accumulated other comprehensive income, before tax	$	82,648		$	—	$	5,307		$	87,955
Intraperiod tax allocation recorded as a benefit from income taxes		(32,792	)		—		(431	)		(33,223	)
Intraperiod tax allocation recorded as an accrued liability		—			—		(2,004	)		(2,004	)
Accumulated other comprehensive income, net of tax	$	49,856		$	—	$	2,872		$	52,728

Description	At December 31, 2013			Sales of Regulus Shares During Three Months Ended March 31, 2014		All Other Activity During Three Months Ended March 31, 2014			Balance at March 31, 2014
Carrying value	$	12,449		$	—	$	—		$	12,449
Accumulated other comprehensive income, before tax		33,003			—		10,026			43,029
Investment in equity securities of Regulus, as reported	$	45,452		$	—	$	10,026		$	55,478
Accumulated other comprehensive income, before tax	$	33,003		$	—	$	10,026		$	43,029
Intraperiod tax allocation recorded as a benefit from income taxes		(13,267	)		—		(2,699	)		(15,966	)
Intraperiod tax allocation recorded as an accrued liability		—			—		(1,380	)		(1,380	)
Accumulated other comprehensive income, net of tax	$	19,736		$	—	$	5,947		$	25,683

We obtain fair value measurement data for our marketable securities from independent pricing services. We perform validation procedures to ensure the reasonableness of this data. This includes meeting with the independent pricing services to understand the methods and data sources used. Additionally, we perform our own review of prices received from the independent pricing services by comparing these prices to other sources and confirming those securities are trading in active markets.

The following tables summarize our marketable securities, other than our holdings in Regulus noted above, at March 31, 2015 and December 31, 2014, in thousands:

	At March 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Certificates of deposit (Due within 1 year)	$	4,300	$	1	$	—		$	4,301
Commercial paper (Due within 1 year)		43,351		2		(7	)		43,346
Corporate notes (Due within 1 year)		566,815		64		(182	)		566,697
Corporate notes (Due after 1 year through 2 years)		381,069		53		(326	)		380,796
Municipal debt securities (Due within 1 year)		9,002		17		—			9,019
U.S. government-sponsored enterprise securities (Due within 1 year)		13,300		2		(1	)		13,301
U.S. government-sponsored enterprise securities (Due after 1 year through 2 years)		76,370		30		(12	)		76,388
U.S. treasury securities (Due within 1 year)		23,735		4		—			23,739
U.S. treasury securities (Due after 1 year through 2 years)		26,575		12		—			26,587
Total	$	1,144,517	$	185	$	(528	)	$	1,144,174

	At December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Certificates of deposit (Due within 1 year)	$	24,300	$	—	$	—		$	24,300
Commercial paper (Due within 1 year)		40,785		11		—			40,796
Corporate notes (Due within 1 year)		449,044		14		(293	)		448,765
Corporate notes (Due after 1 year through 2 years)		214,510		—		(730	)		213,780
Municipal debt securities (Due after 1 year through 2 years)		9,002		3		—			9,005
U.S. government-sponsored enterprise securities (Due within 1 year)		13,069		—		(1	)		13,068
U.S. government-sponsored enterprise securities (Due after 1 year through 2 years)		51,879		—		(91	)		51,788
U.S. treasury securities (Due after 1 year through 2 years)		5,254		—		(6	)		5,248
Total	$	807,843	$	28	$	(1,121	)	$	806,750