EARNINGS PER SHARE

We apply the two-class method of computing earnings per share, which requires the calculation of separate earnings per share amounts for our non-vested time-based restricted stock awards with non-forfeitable dividends and for our common stock. Our non-vested time-based restricted stock awards with non-forfeitable rights to dividends are considered securities which participate in undistributed earnings with common stock. Under the two-class computation method, net losses are not allocated to participating securities unless the holder of the security has a contractual obligation to share in the losses. Our non-vested time-based restricted stock awards with non-forfeitable dividends do not have such an obligation so they are not allocated losses.

Below is a summary of the components used to calculate basic and diluted earnings per share (in thousands, except per share):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2018			2017			2018			2017
Numerator:
Net income	$	38,001		$	22,445		$	85,369		$	89,734
Less: Preferred dividends	(3,710		)	(4,200		)	(12,962		)	(12,600		)
Premium on redemption of preferred stock	—			—			(3,277		)	—
Allocation to participating securities	(122		)	(69		)	(249		)	(305		)
Attributable to non-controlling interest	(100		)	(55		)	(204		)	(289		)
Net income attributable to common stockholders, net of amount allocated to participating securities	$	34,069		$	18,121		$	68,677		$	76,540
Denominator:
Weighted average common shares outstanding - basic	103,666			103,253			103,603			98,105
Dilutive effect of equity-based compensation awards	155			379			265			366
Weighted average common shares outstanding - diluted	103,821			103,632			103,868			98,471
Earnings per share:
Basic	$	0.33		$	0.18		$	0.66		$	0.78
Diluted	$	0.33		$	0.17		$	0.66		$	0.78

All outstanding stock options were included in the computation of diluted earnings per share for the three and nine months ended September 30, 2018 and 2017 due to their dilutive effect. The Common Units held by the non-controlling interest holders have been excluded from the denominator of the diluted earnings per share as there would be no effect on the amounts since the limited partners' share of income would also be added to derive net income attributable to common stockholders. We had unvested performance-based restricted stock awards of 453,664 shares for the three and nine months ended September 30, 2018 and 464,924 shares for the three and nine months ended September 30, 2017, which were excluded from the denominator of the diluted earnings per share as the awards had not achieved the requisite performance conditions for vesting at each period end.