Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 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):

	December 31, 2014						December 31, 2013
	Level 1		Level 2		Total		Level 1		Level 2		Total
Assets:
Cash equivalents:
Money market funds	$	9,785	$	—	$	9,785	$	13,761	$	—	$	13,761
Commercial paper		—		12,248		12,248		—		19,629		19,629
Short-term investments:
Corporate debt securities		—		88,494		88,494		—		76,786		76,786
Municipal bonds		—		9,945		9,945		—		29,106		29,106
U.S. government agency bonds		—		11,313		11,313		—		18,050		18,050
Asset-backed securities		—		10,336		10,336		—		4,209		4,209
Total	$	9,785	$	132,336	$	142,121	$	13,761	$	147,780	$	161,541
Liabilities:
Interest rate swap contracts (1)	$	—	$	—	$	—	$	—	$	154	$	154
Total	$	—	$	—	$	—	$	—	$	154	$	154

·	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):

	December 31, 2014				December 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value
Credit Agreement (carrying value including current maturities)	$	120,000	$	120,000	$	135,000	$	135,000
Convertible debt (par value)		150,000		178,920		150,000		199,800

Allowance for Doubtful Accounts Receivable

The activity in our allowance for doubtful accounts receivable is as follows (in thousands):

	2014			2013			2012
Balance, beginning of year	$	2,359		$	3,147		$	2,421
Additions (reductions) to expense		1,406			(354	)		1,039
Write-offs		(465	)		(280	)		(174	)
Other		23			(154	)		(139	)
Balance, end of year	$	3,323		$	2,359		$	3,147

Net Income Attributed to Common Stock and Participating Restricted Common Stock

The amounts attributed to both common stock and participating restricted stock used as the numerators in both the basic and diluted EPS calculations are as follows (in thousands):

	2014		2013		2012
Net income attributed to:
Common stock	$	36,959	$	51,351	$	48,853
Participating common restricted stock		—		—		26
Total	$	36,959	$	51,351	$	48,879

Calculation of the Denominator of the Basic and Diluted Earnings (Loss) per Share (EPS) Computations

The weighted-average shares outstanding used in the basic and diluted EPS denominators related to common stock and participating restricted stock are as follows (in thousands):

	2014		2013		2012
Weighted-average shares outstanding – Basic:
Common stock		32,449		32,117		32,142
Participating common restricted stock		—		—		17
Total		32,449		32,117		32,159
Weighted-average shares outstanding – Diluted:
Common stock		33,736		32,873		32,459
Participating common restricted stock		—		—		17
Total		33,736		32,873		32,476

Reconciliation of the Basic and Diluted EPS denominators

The reconciliation of the basic and diluted EPS denominators related to the common shares is included in the following table (in thousands):

	2014		2013		2012
Basic weighted-average common shares		32,449		32,117		32,142
Dilutive effect of common stock options		—		1		11
Dilutive effect of non-participating restricted common stock		569		550		306
Dilutive effect of 2010 Convertible Notes		717		205		—
Dilutive effect of Stock Warrants		1		—		—
Diluted weighted-average common shares		33,736		32,873		32,459