Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Earnings per share

				Six months ended June 30,				Three months ended June 30,
				2013		2012		2013		2012
Net earnings				$	194,012	$	176,077	$	88,162	$	93,493
Less: net earnings attributable to unvested restricted stock					(3,227)		(3,238)		(1,445)		(1,775)
		Net earnings available to common stock		$	190,785	$	172,839	$	86,717	$	91,718
Weighted-average common shares outstanding					98,965		100,802		98,870		99,563
Dilutive effect of outstanding securities (determined using
	treasury stock method)				245		181		251		288
		Weighted-average common shares and potential
			common shares outstanding		99,210		100,983		99,121		99,851
Anti-dilutive securities not included in treasury stock
	method computation				89		1,990		109		642