| Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] |
The calculation of basic and diluted net income per share is as follows (in thousands, except per share amounts): | | | | | | | | | | | | | | | | | Three Months Ended September 30, | Nine Months Ended September 30, | | 2013 | | 2012 | 2013 | | 2012 | Basic: | |
| | |
| |
| | |
| Net income | $ | 7,755 |
| | $ | 6,920 |
| $ | 17,156 |
| | $ | 10,646 |
| Weighted average shares outstanding — basic | 35,133 |
| | 33,193 |
| 34,499 |
| | 33,316 |
| Net income per share — basic | $ | 0.22 |
| | $ | 0.21 |
| $ | 0.50 |
| | $ | 0.32 |
| Diluted: | |
| | |
| |
| | |
| Net income | $ | 7,755 |
| | $ | 6,920 |
| $ | 17,156 |
| | $ | 10,646 |
| Weighted average shares outstanding — basic | 35,133 |
| | 33,193 |
| 34,499 |
| | 33,316 |
| Add: Dilutive effect of employee stock plans | 1,057 |
| | 875 |
| 967 |
| | 925 |
| Weighted average shares outstanding — diluted | 36,190 |
| | 34,068 |
| 35,466 |
| | 34,241 |
| Net income per share — diluted | $ | 0.21 |
| | $ | 0.20 |
| $ | 0.48 |
| | $ | 0.31 |
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