Earnings Per Share

Basic net income per share (“EPS”) is calculated by dividing net income attributable to common stockholders by the weighted average shares outstanding during the period. Diluted EPS is calculated by adjusting weighted average shares outstanding for the dilutive effect of potential common shares, determined using the treasury-stock method. For purposes of the diluted EPS calculation, stock options, restricted stock and restricted stock unit awards are considered to be potential common shares. Performance-based restricted stock units are not included in the calculation of diluted EPS until they are contingently issuable.

The basic and diluted EPS calculations for the three and nine months ended September 30, 2018 and 2017 are presented below:



	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands, except per share amounts)	2018		2017		2018		2017
Income attributable to common stockholders	$	35,858	$	18,443	$	91,622	$	39,783

Weighted average common shares outstanding, basic	67,329		66,958		67,246		66,860
Effect of dilutive securities:
Restricted stock units	399		248		321		212
Stock options	166		175		155		201
Restricted stock	2		61		21		68
Weighted average common shares outstanding, diluted	67,896		67,442		67,743		67,341

Basic income per common share	$	0.53	$	0.28	$	1.36	$	0.60
Diluted income per common share	$	0.53	$	0.27	$	1.35	$	0.59

The following table provides the securities that could potentially dilute EPS in the future, but were not included in the computation of diluted EPS for the periods presented because to do so would have been anti-dilutive. The amounts included in this table exclude performance-based restricted stock units. As of September 30, 2018, the number of currently outstanding performance-based restricted stock units that are issued upon vesting could range from zero to a maximum of 0.6 million.



	Three Months Ended September 30,		Nine Months Ended September 30,
(in thousands)	2018	2017	2018	2017
Stock options	—	1	—	1
Restricted stock units	—	13	—	13