Basis of Presentation (Tables)

3 Months Ended

Mar. 31, 2016

The following is a reconciliation of basic earnings per common share to diluted earnings per share:



	Three Months Ended March 31,
(in thousands, except per share amounts)	2016		2015
Net income available to common stockholders	$	16,343	$	10,051
Basic weighted-average shares outstanding	48,297		49,208
Dilutive effect of potential common stock equivalents — stock options and restricted stock units	153		200
Diluted weighted-average shares outstanding	48,450		49,408
Earnings per common share:
Basic	$	0.34	$	0.20
Diluted	$	0.34	$	0.20
Potentially dilutive securities excluded from earnings per diluted share because their effect is anti-dilutive	—		—

The following table represents the Company’s stock option and restricted stock unit activity for the three months ended March 31, 2016 and 2015:



	Three Months Ended March 31,
(in thousands)	2016		2015
Stock-based compensation expense recognized in operating expenses	$	2,480	$	3,084
Less: Tax benefit of stock-based compensation expense in provision for income taxes	895		1,052
Stock-based compensation expense, net of tax	$	1,585	$	2,032
Fair value of shares vested	$	2,350	$	2,784
Proceeds to the Company from the exercise of stock-based compensation	$	1,012	$	5,484
Tax effect from the exercise of stock-based compensation, including shortfall tax benefits	$	24	$	(184	)



	At March 31,
(in thousands)	2016		2015
Stock-based compensation cost capitalized in inventory	$	253	$	276

The balances of the Company’s primary financial instruments were as follows:



	At March 31,				At December 31,
(in thousands)	2016		2015		2015
United States Treasury securities and money market funds	$	71,442	$	91,569	$	76,047

The following table presents the Company’s effective tax rates and income tax expense for the three months ended March 31, 2016 and 2015:



	Three Months Ended March 31,
(in thousands, except percentages)	2016			2015
Effective tax rate	38.1		%	38.1		%
Provision for income taxes	$	10,063		$	6,191