Net Income per Common Share (Tables)

6 Months Ended

Jun. 30, 2012

Net Income per Common Share

Computation of basic and diluted earnings per share

	Three Months Ended June 30,				Six Months Ended June 30,
	2011		2012		2011		2012
Numerator:
Net income	$	34,231	$	26,973	$	68,529	$	47,763
Denominator:
Weighted average number of common shares outstanding—basic		31,301		27,317		32,171		27,258
Common stock equivalents—stock options		523		328		508		380
Common stock equivalents—restricted stock		10		10		13		12
Common stock equivalents—restricted stock units		69		61		83		81
Common stock equivalents—employee stock purchase plan		—		1		—		1
Weighted average number of common shares outstanding—diluted		31,903		27,717		32,775		27,732
Net income per common share—basic	$	1.09	$	0.99	$	2.13	$	1.75
Net income per common share—diluted	$	1.07	$	0.97	$	2.09	$	1.72