Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2012

Earnings Per Share [Abstract]

Earnings per share

		Six months ended June 30,				Three months ended June 30,
		2012		2011		2012		2011
Net earnings		$	176,077	$	116,468	$	93,493	$	69,478
Less: net earnings attributable to unvested restricted stock			(3,238)		(1,601)		(1,775)		(1,003)
	Net earnings available to common stock	$	172,839	$	114,867	$	91,718	$	68,475
Weighted-average common shares outstanding			100,802		112,569		99,563		111,389
Dilutive effect of outstanding options (determined using
	treasury stock method)		181		375		288		368
	Weighted-average common shares and potential common
	shares outstanding		100,983		112,944		99,851		111,757
Anti-dilutive stock options not included in treasury stock
	method computation		1,990		917		642		424