Fair Value Measurements

12 Months Ended

Dec. 31, 2013

Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]

Fair Value Measurements

Fair Value Measurements

The following table presents our fair value hierarchy for our assets and liabilities measured at fair value on a recurring basis at December 31, 2013 (in thousands):

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash	$	69,333	$	—	$	—	$	69,333
Money market funds	35,248		—		—		35,248
Commercial paper	—		261,722		—		261,722
Short-term investments:
Commercial paper	—		124,319		—		124,319
Corporate notes and bonds	—		143,932		—		143,932
Long-term investments:
Corporate notes and bonds	—		255,356		—		255,356
Total	$	104,581	$	785,329	$	—	$	889,910

The following table presents our fair value hierarchy for our assets and liabilities measured at fair value on a recurring basis at December 31, 2012 (in thousands): 

	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash	$	47,478	$	—	$	—	$	47,478
Money market funds	35,429		—		—		35,429
Commercial paper	—		36,082		—		36,082
Short-term investments:
Commercial paper	—		36,753		—		36,753
Corporate notes and bonds	—		157,948		—		157,948
U.S. government agency securities	—		1,001		—		1,001
Total	$	82,907	$	231,784	$	—	$	314,691

We determine the fair value of our security holdings based on pricing from our service provider and market prices from industry-standard independent data providers. Such market prices may be quoted prices in active markets for identical assets (Level 1 inputs) or pricing determined using inputs other than quoted prices that are observable either directly or indirectly (Level 2 inputs), such as yield curve, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, broker and dealer quotes, as well as other relevant economic measures.