Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2011

Net Income Per Share [Abstract]

Summary of the net income allocated to common shares and the basic and diluted shares used in the net income per share computations

The following table summarizes the net income allocated to common shares and the basic and diluted shares used in the net income per share computations:

	Year ended December 31,
	2011			2010			2009
	(in thousands)
Net income	$	30,470		$	22,440		$	16,574
Less income allocated to participating securities		(908	)		(657	)		(462	)
Net income allocated to common shares	$	29,562		$	21,783		$	16,112
Weighted average common shares outstanding		25,405			25,254			24,768
Incremental shares from assumed conversions of common stock options		92			114			148
Adjusted weighted average common shares outstanding		25,497			25,368			24,916
Potentially dilutive securities not included in weighted average share calculation due to anti-dilutive effect		29			372			541