Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Assets Measured on Recurring Basis

The composition of our financial instruments among the three Levels of the fair value hierarchy are as follows (in thousands):

	September 30, 2015
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds (1)	$	475,383	$	—	$	—	$	475,383
U.S. government and government agency debt securities		—		196,913		—		196,913
Corporate debt securities		—		332,276		—		332,276
Total	$	475,383	$	529,189	$	—	$	1,004,572
Liabilities:
Contingent consideration	$	—	$	—	$	21,778	$	21,778
	December 31, 2014
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds (1)	$	41,595	$	—	$	—	$	41,595
U.S. government and government agency debt securities		—		404,982		—		404,982
Corporate debt securities		—		611,624		—		611,624
Total	$	41,595	$	1,016,606	$	—	$	1,058,201
Liabilities:
Contingent consideration	$	—	$	—	$	44,420	$	44,420

⁽¹⁾  Includes amounts classified as cash and cash equivalents.