Basis of Presentation (Details) (USD $)	3 Months Ended		9 Months Ended		6 Months Ended	36 Months Ended	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Item	Sep. 30, 2011	Jun. 30, 2012 Error attributable to the misapplication of U.S. GAAP	Dec. 31, 2011 Error attributable to the misapplication of U.S. GAAP	Sep. 30, 2012 Error attributable to the misapplication of U.S. GAAP Restatement adjustment
Basis of Presentation
Number of weeks in each fiscal quarter for 52-week fiscal year	91 days
Accounting Review
Minimum number of multiple element arrangements examined			100
Accounting Review
Overstated cumulative net income from continuing operations						$ 600,000
Understated cumulative net income from continuing operations					1,100,000
Revenues	132,715,000	267,959,000	409,171,000	787,450,000			5,400,000
Income from continuing operations	$ 7,698,000	$ 52,617,000	$ 35,171,000	$ 166,914,000			$ 500,000
Income Per Common Share
Basic weighted average shares outstanding (in shares)	38,577,000	39,335,000	38,402,000	40,132,000
Dilutive effect of stock options and restricted stock (in shares)	592,000	734,000	604,000	983,000
Dilutive effect of convertible notes (in shares)				826,000
Diluted weighted average shares outstanding (in shares)	39,169,000	40,069,000	39,006,000	41,941,000
Dilutive effect of assumed conversion of convertible debt (in shares)				800,000