Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2014

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. We break down the inputs used to measure fair value for these assets at June 30, 2014 and December 31, 2013 as follows (in thousands):

	At June 30, 2014		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	70,638	$	70,638	$	—	$	—
Corporate debt securities (1)		339,847		—		339,847		—
Debt securities issued by U.S. government agencies (1)		98,373		—		98,373		—
Debt securities issued by the U.S. Treasury		11,264		11,264		—		—
Debt securities issued by states of the United States and political subdivisions of the states (1)		66,391		—		66,391		—
Investment in Regulus Therapeutics Inc.		56,678		56,678		—		—
Equity securities (2)		2,481		625		—		1,856
Total	$	645,672	$	139,205	$	504,611	$	1,856

	At December 31, 2013		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	133,233	$	133,233	$	—	$	—
Corporate debt securities (1)		407,897		—		407,897		—
Debt securities issued by U.S. government agencies		64,432		—		64,432		—
Debt securities issued by the U.S. Treasury		15,328		15,328		—		—
Debt securities issued by states of the United States and political subdivisions of the states		22,255		—		22,255		—
Investment in Regulus Therapeutics Inc.		52,096		52,096		—		—
Equity securities (2)		1,276		1,276		—		—
Total	$	696,517	$	201,933	$	494,584	$	—

(1)

Includes investments classified as cash equivalents on our condensed consolidated balance sheet.

(2)

Included in other current assets 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 June 30, 2014 (in thousands):


Beginning balance of Level 3 investments	$	-
Total gain included in accumulated other comprehensive income (loss)		1,856
Ending balance of Level 3 investments	$	1,856

- 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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