Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2014

The following table represents the fair value hierarchy based upon three levels of inputs, of which Levels 1 and 2 are considered observable and Level 3 is unobservable, for our financial assets and liabilities measured at fair value (in thousands):

	September 30, 2014						December 31, 2013
	Level 1			Level 2		Total	Level 1		Level 2		Total
Assets:
Cash equivalents:
Money market funds	$	9,810	$	—	$	9,810	$	13,761	$	—	$	13,761
Commercial paper		—		13,248		13,248		—		19,629		19,629
Short-term investments:
Corporate debt securities		—		62,105		62,105		—		76,786		76,786
Municipal bonds		—		19,317		19,317		—		29,106		29,106
U.S. government agency bonds		—		14,027		14,027		—		18,050		18,050
Asset-backed securities		—		12,437		12,437				4,209		4,209
Total	$	9,810	$	121,134	$	130,944	$	13,761	$	147,780	$	161,541
Liabilities:
Interest rate swap contract (1)	$	—	$	—	$	—	$	—	$	154	$	154
Total	$	—	$	—	$	—	$	—	$	154	$	154

(1)	As of December 31, 2013, the fair value of the interest rate swap contract was classified on our Balance Sheet in other current liabilities.

Carrying Value and Estimated Fair Value of Debt

We have chosen not to measure our debt at fair value, with changes recognized in earnings each reporting period. The following table indicates the carrying value and estimated fair value of our debt as of the indicated periods (in thousands):

	September 30, 2014				December 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value
Credit Agreement (carrying value including current maturities)	$	123,750	$	123,750	$	135,000	$	135,000
Convertible debt (par value)		150,000		187,065		150,000		199,800