| Three Months Ended March 31, | ||||||||||||||
| 2021 | 2020 | |||||||||||||
| Basic: | ||||||||||||||
| Net income | $ | 39.3 | $ | 18.5 | ||||||||||
| Weighted average number of common shares during the period | 41.9 | 41.8 | ||||||||||||
| Net income per share – basic | $ | 0.94 | $ | 0.44 | ||||||||||
| Diluted: | ||||||||||||||
| Net income | $ | 39.3 | $ | 18.5 | ||||||||||
| Weighted average number of common shares during the period | 41.9 | 41.8 | ||||||||||||
| Weighted average number of common equivalent shares to reflect the dilutive effect of common stock equivalent securities: | ||||||||||||||
| Stock options | 0.1 | 0.1 | ||||||||||||
| Common stock units related to deferred compensation for employees | — | — | ||||||||||||
| Restricted common stock units related to incentive compensation | 0.1 | 0.1 | ||||||||||||
Total common and common equivalent shares adjusted to calculate diluted earnings per share | 42.1 | 42.0 | ||||||||||||
| Net income per share – diluted | $ | 0.93 | $ | 0.44 | ||||||||||