Summary of Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2011

Summary of Selected Quarterly Financial Data (Unaudited) [Abstract]

Summary of Selected Quarterly Financial Data (Unaudited)

12.  Summary of Selected Quarterly Financial Data (Unaudited)

The following is a summary of selected quarterly financial data for the previous two years (in thousands, except per share data):

	Quarters Ended
	March 31		June 30		Sept. 30		Dec. 31
2011
Revenues	$	317,703	$	350,599	$	342,170	$	335,451
Income from operations		10,116		22,807		24,668		22,203
Net income		12,335		21,217		16,473		17,369
Basic income per share		0.21		0.36		0.28		0.29
Diluted income per share		0.21		0.36		0.28		0.29
2010
Revenues	$	296,190	$	337,726	$	314,519	$	346,142
Income from operations		17,365		12,228		19,356		24,065
Net income		9,268		6,345		10,629		21,227	(1)
Basic income per share		0.16		0.11		0.18		0.36
Diluted income per share		0.16		0.11		0.18		0.36

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(1) Includes a reduction in income tax expense resulting from the reinstatement of the federal research and development tax credit that increased net income by $7.4 million.