Earnings Per Share

12 Months Ended

Dec. 31, 2020

Basic earnings per share ("EPS") is calculated by dividing net income (loss) by the weighted average number of shares of common stock outstanding. Diluted EPS includes the components of basic EPS and also gives effect to dilutive common stock equivalents. Under the treasury stock method, diluted EPS reflects the potential dilution that could occur if securities or other instruments that are convertible into common stock were exercised or could result in the issuance of common stock. Potentially dilutive common stock equivalents include unvested restricted stock, restricted stock units, and convertible debt instruments and warrants.

The following table summarizes the computation of basic and diluted earnings (loss) per share amounts presented in the consolidated financial statements.


	Years Ended December 31,
(in thousands, except for per share amounts)	2020		2019		2018
Income attributable to common stockholders:
Net income (loss)	$	82,019	$	(267,931)	$	(528,258)

Weighted average shares outstanding - basic	183,498		185,907		187,468
Effect of dilutive securities - Unvested restricted stock, restricted stock units, and warrants	888		—		—
Weighted average shares outstanding - diluted	184,386		185,907		187,468

Basic earnings (loss) per common share:
Net income (loss) per share attributable to common stockholders	$	0.45	$	(1.44)	$	(2.82)

Diluted earnings (loss) per common share:
Net income (loss) per share attributable to common stockholders	$	0.44	$	(1.44)	$	(2.82)

For the purposes of computing diluted EPS, weighted average shares outstanding do not include potentially dilutive securities that are anti-dilutive under the treasury stock method and performance-based equity awards are included based on the attainment of the applicable performance metrics as of the end of the reporting period. The following potentially dilutive securities were excluded from the computation of diluted EPS:


	Years Ended December 31,
(in millions)	2020	2019(1)	2018(1)
Non-performance-based restricted stock and restricted stock units	6.8	6.4	5.6
Performance-based restricted stock and restricted stock units	1.6	1.1	0.8
Warrants(2)	—	—	0.5

(1)As a result of the net loss reported for the period, all unvested restricted stock, restricted stock units, convertible debt instruments, and potential shares issuable under warrants were antidilutive for the period and as such were not included in the computation of diluted weighted average shares outstanding.

(2)The option to exercise the warrants to acquire the Company's common stock outstanding at December 31, 2018 expired unexercised in 2019.

For the year ended December 31, 2018, the calculation of diluted weighted average shares outstanding excludes the impact of conversion of the principal amount of $316.3 million of the Company's 2.75% convertible senior notes which were repaid in cash at their maturity on June 15, 2018.