CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Millions, except Share data | Sep. 30, 2011 | Dec. 31, 2010 |
|---|---|---|
| Current assets: | ||
| Allowance for doubtful accounts | $ 2.3 | $ 2.8 |
| Stockholders' equity: | ||
| Common stock, par or stated value per share (in dollars per share) | $ 0.01 | $ 0.01 |
| Common stock, shares authorized (in shares) | 200,000,000 | 200,000,000 |
| Common stock, shares issued (in shares) | 35,367,264 | 35,367,264 |
| Treasury stock, shares (in shares) | 2,452,923 | 2,558,009 |