15. Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2011		2010		2011		2010
Numerator for basic and diluted earnings per share — net income attributable to common stockholders	$	69,847	$	45,646	$	93,219	$	71,458

Denominator for basic earnings per share — weighted average shares		176,445		123,808		165,755		123,541
Effect of dilutive securities:
Employee stock options		178		102		184		104
Non-vested restricted shares		249		414		232		414
Convertible senior unsecured notes		616		—		287		—

Dilutive potential common shares		1,043		516		703		518

Denominator for diluted earnings per share — adjusted weighted average shares		177,488		124,324		166,458		124,059

Basic earnings per share	$	0.40	$	0.37	$	0.56	$	0.58

Diluted earnings per share	$	0.39	$	0.37	$	0.56	$	0.58

The diluted earnings per share calculations exclude the dilutive effect of 287,000 and 381,000 stock options for the three and six months ended June 30, 2011 and 2010, respectively, because the exercise prices were more than the average market price. The Series H Cumulative Convertible and Redeemable Preferred Stock and Series I Cumulative Convertible Perpetual Preferred Stock were not included in the 2011 calculation as the effect of conversions into common stock was anti-dilutive for that period.