| Schedule of Quarterly Financial Information [Table Text Block] |
| | Quarters Ended | | | December 31 | | September 30 | | June 30 (2) | | March 31 | | | (amounts in thousands, except per share data) | | 2012 | | | | | | | | | | | | | Net revenues | $ | 102,092 | | $ | 102,295 | | $ | 104,571 | | $ | 79,966 | | Operating income | $ | 30,951 | | $ | 29,385 | | $ | 5,368 | | $ | 10,890 | | Net income (loss) | $ | 7,347 | | $ | 8,177 | | $ | (3,207) | | $ | (1,049) | | Basic net income (loss) per common share (1) | $ | 0.20 | | $ | 0.22 | | $ | (0.09) | | $ | (0.03) | | Weighted average basic common shares outstanding | | 36,935 | | | 36,735 | | | 36,686 | | | 36,483 | | Diluted net income (loss) per common share (1) | $ | 0.19 | | $ | 0.22 | | $ | (0.09) | | $ | (0.03) | | Weighted average diluted common and common equivalent shares outstanding | | 37,837 | | | 37,548 | | | 36,686 | | | 36,483 | | | | | | | | | | | | | | | | Quarters Ended | | | December 31 | | September 30 | | June 30 (3) | | March 31 | | | (amounts in thousands, except per share data) | | 2011 | | | | | | | | | | | | | Net revenues | $ | 95,134 | | $ | 100,429 | | $ | 104,650 | | $ | 82,514 | | Operating income | $ | 25,920 | | $ | 22,263 | | $ | 24,015 | | $ | 7,275 | | Net income | $ | 10,524 | | $ | 8,231 | | $ | 46,501 | | $ | 1,021 | | Basic net income per common share (1) | $ | 0.29 | | $ | 0.23 | | $ | 1.28 | | $ | 0.03 | | Weighted average basic common shares outstanding | | 36,380 | | | 36,367 | | | 36,353 | | | 36,053 | | Diluted net income per common share (1) | $ | 0.28 | | $ | 0.22 | | $ | 1.23 | | $ | 0.03 | | Weighted average diluted common and common equivalent shares outstanding | | 37,473 | | | 37,463 | | | 37,742 | | | 37,865 |
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| Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] |
| | | Quarter Ended June 30, 2011 | | | | As | | | | | | | | | | Previously | | | | | | | | | | Reported | | Adjustment | | As Revised | | | | (amounts in thousands, except per share data) | | | | | | | | | | | | | Income taxes (benefit) | | $ | (29,968) | | $ | 2,233 | | $ | (27,735) | | Net income (loss) | | $ | 48,734 | | $ | (2,233) | | $ | 46,501 | | Net income per share: | | | | | | | | | | | Basic | | $ | 1.34 | | $ | (0.06) | | $ | 1.28 | | Diluted | | $ | 1.29 | | $ | (0.06) | | $ | 1.23 |
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