| Schedule of Quarterly Financial Information [Table Text Block] |
| Quarters Ended | | December 31 | | September 30 | | June 30 | | March 31 | | (amounts in thousands, except per share data) | | 2015 | | | | | | | | | | | | | Net revenues | $ | 117,704 | | $ | 114,662 | | $ | 100,592 | | $ | 78,420 | | Operating income | $ | 32,555 | | $ | 23,159 | | $ | 20,615 | | $ | 9,253 | | Net income (loss) available to the Company | $ | 14,088 | | $ | 8,442 | | $ | 6,747 | | $ | (93) | | Net income (loss) available to common shareholders | $ | 13,675 | | $ | 8,103 | | $ | 6,747 | | $ | (93) | | Net income (loss) available to common shareholders | | | | | | | | | | | | | per share - basic (1) | $ | 0.36 | | $ | 0.21 | | $ | 0.18 | | $ | - | | Weighted average common shares outstanding - basic | | 38,088 | | | 38,076 | | | 38,074 | | | 38,026 | | Net income (loss) available to common shareholders | | | | | | | | | | | | | per share - diluted (1) | $ | 0.34 | | $ | 0.21 | | $ | 0.17 | | $ | - | | Weighted average common shares outstanding - diluted | | 40,974 | | | 38,913 | | | 38,929 | | | 38,026 | | | | | | | | | | | | | | Quarters Ended | | December 31 | | September 30 | | June 30 | | March 31 | | (amounts in thousands, except per share data) | | 2014 | | | | | | | | | | | | | Net revenues | $ | 101,513 | | $ | 99,840 | | $ | 100,201 | | $ | 78,235 | | Operating income | $ | 28,531 | | $ | 21,205 | | $ | 23,916 | | $ | 11,924 | | Net income (loss) available to the Company | $ | 10,850 | | $ | 6,473 | | $ | 8,137 | | $ | 1,363 | | Net income (loss) available to common shareholders | $ | 10,850 | | $ | 6,473 | | $ | 8,137 | | $ | 1,363 | | Net income (loss) available to common shareholders | | | | | | | | | | | | | per share - basic (1) | $ | 0.29 | | $ | 0.17 | | $ | 0.22 | | $ | 0.04 | | Weighted average common shares outstanding - basic | | 37,779 | | | 37,693 | | | 37,687 | | | 37,660 | | Net income (loss) available to common shareholders | | | | | | | | | | | | | per share - diluted (1) | $ | 0.28 | | $ | 0.17 | | $ | 0.21 | | $ | 0.04 | | Weighted average common shares outstanding - diluted | | 38,730 | | | 38,482 | | | 38,446 | | | 38,501 |
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