Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

Schedule of assets measured at fair value on a recurring basis

We measure the following major security types at fair value on a recurring basis. The following summary breaks down the fair-value hierarchy that we used to value each security at March 31, 2015 and December 31, 2014 (in thousands):

	At March 31, 2015		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents (1)	$	112,777	$	112,777	$	—	$	—
Corporate debt securities (2)		328,108		—		328,108		—
Debt securities issued by U.S. government agencies (2)		115,542		—		115,542		—
Debt securities issued by the U.S. Treasury (2)		6,003		6,003		—		—
Debt securities issued by states of the United States and political subdivisions of the states (3)		106,096		—		106,096		—
Investment in Regulus Therapeutics Inc.		93,446		93,446		—		—
Total	$	761,972	$	212,226	$	549,746	$	—

	At December 31, 2014		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents (1)	$	104,680	$	104,680	$	—	$	—
Corporate debt securities (4)		372,002		—		372,002		—
Debt securities issued by U.S. government agencies (2)		109,855		—		109,855		—
Debt securities issued by the U.S. Treasury (5)		19,017		19,017		—		—
Debt securities issued by states of the United States and political subdivisions of the states (6)		105,033		—		105,033		—
Investment in Regulus Therapeutics Inc.		81,881		—		—		81,881
Total	$	792,468	$	123,697	$	586,890	$	81,881

(1)

Included in cash and cash equivalents on our condensed consolidated balance sheet.

(2)

Included in short-term investments on our condensed consolidated balance sheet.

(3)

$9.0 million included in cash and cash equivalents on our condensed consolidated balance sheet, with the difference included in short-term investments on our condensed consolidated balance sheet.

(4)

$0.8 million included in cash and cash equivalents on our condensed consolidated balance sheet, with the difference included in short-term investments on our condensed consolidated balance sheet.

(5)

$10 million included in cash and cash equivalents on our condensed consolidated balance sheet, with the difference included in short-term investments on our condensed consolidated balance sheet.

(6)

$9.3 million included in cash and cash equivalents on our condensed consolidated balance sheet, with the difference included in short-term investments on our condensed consolidated balance sheet.

Summary of investments measured at fair value on a recurring basis using significant unobservable inputs (Level 3)

The following is a summary of our investments measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2015 (in thousands):


Beginning balance of Level 3 investments	$	81,881
Total gain included in accumulated other comprehensive income (loss)		22,377
Transfers out of Level 3 investments		(104,258	)
Ending balance of Level 3 investments	$	—

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

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