Earnings per Common Share

Basic earnings per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period presented, excluding unvested restricted stock. Diluted earnings per share is calculated by dividing net income by the weighted average number of common shares determined for the basic earnings per share computation plus the dilutive effects of stock-based compensation using the treasury stock method.

The following table sets forth the computation of basic and diluted earnings per share for the three and nine month periods ended September 30, 2018 and 2017:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Net income	$	41.4	$	27.3	$	119.8	$	72.3
Weighted average common shares outstanding for basic earnings per share computation	58,254,575		56,094,401		56,951,029		49,514,818
Dilutive effects of stock-based compensation	385,900		436,467		378,998		486,064
Weighted average common shares outstanding for diluted earnings per common share computation	58,640,475		56,530,868		57,330,027		50,000,882

Basic earnings per common share	$	0.71	$	0.49	$	2.10	$	1.46
Diluted earnings per common share	$	0.71	$	0.48	$	2.09	$	1.45

Anti-dilutive unvested time restricted stock	4,376		—		120,553		94,210

The Company had 154,176 and 174,696 shares of unvested restricted stock as of September 30, 2018 and 2017, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.