Three Months Ended
March 31,

2012

2011

(in thousands, except
per share data)

Income (numerator):

Basic:

Net income

$

50,974

$

39,792

Net income attributable to participating securities

(1,217

)

(874

)

Net income attributable to common stock – basic

$

49,757

$

38,918

Diluted:

Net income

$

50,974

$

39,792

Net income attributable to participating securities

(1,216

)

(873

)

Net income attributable to common stock – diluted

$

49,758

$

38,919

Weighted average shares (denominator):

Weighted average shares – basic

48,254

47,898

Diluted effect of stock options

45

41

Weighted average shares – diluted

48,299

47,939

Basic income per common share

$

1.03

$

0.81

Diluted income per common share

$

1.03

$

0.81