11. Earnings per Share

The Company has unvested shares of restricted stock outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.


	Three Months Ended March 31,
	2012			2011
Net income	$	87,813		$	83,544
Less:
Net income attributable to participating securities		(610	)		(778	)

Net income attributable to common shareholders	$	87,203		$	82,766

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:


	Three Months Ended March 31,
	2012		2011
Weighted average common shares—basic		66,109,297		65,745,555
Plus incremental shares from:
Assumed exercise of options		449,220		367,303

Weighted average common shares—diluted		66,558,517		66,112,858

Earnings per share:
Basic	$	1.32	$	1.26
Diluted	$	1.31	$	1.25

Excluded from the computation of diluted earnings per share are options to purchase 67,098 and 221,639 shares of common stock for the three months ended March 31, 2012 and 2011, respectively. These options were outstanding during the periods reported but were excluded because the option exercise price was greater than the average market price of the shares.