Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Reconciliation between Basic and Diluted Weighted Average Shares Outstanding

The following is a reconciliation between basic and diluted weighted average shares outstanding for the years ended December 31:

(in thousands, except per share data)	2012			2011			2010
Net income	$	184,045		$	163,995		$	161,752
Net income attributable to unvested awarded performance stock		(5,313	)		(5,099	)		(5,097	)
Net income attributable to common shares	$	178,732		$	158,896		$	156,655
Weighted average basic number of common shares outstanding		143,507			143,029			142,412
Less unvested awarded performance stock included in weighted average basic share outstanding		(4,143	)		(4,447	)		(4,488	)
Weighted average number of common shares outstanding for basic earnings per common share		139,364			138,582			137,924
Dilutive effect of stock options		2,646			1,682			1,394
Weighted average number of shares outstanding		142,010			140,264			139,318
Net income per share:
Basic	$	1.28		$	1.15		$	1.14
Diluted	$	1.26		$	1.13		$	1.12