Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2012

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,
	2012			2011			2010
	(in thousands)
Net income	$	40,402		$	30,470		$	22,440
Less distributed and undistributed earnings allocated to participating securities		(1,224	)		(908	)		(657	)
Net income allocated to common shares	$	39,178		$	29,562		$	21,783
Weighted average common shares outstanding		25,007			25,405			25,254
Incremental shares from assumed conversions of common stock options		60			92			114
Adjusted weighted average common shares outstanding		25,067			25,497			25,368
Potentially dilutive securities not included in weighted average share calculation due to anti-dilutive effect		29			29			372