Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2015

Earnings Per Share [Abstract]

Earnings per share

				Six months ended June 30,				Three months ended June 30,
				2015		2014		2015		2014
Net earnings				$	193,334	$	205,047	$	80,417	$	97,136
Less: net earnings attributable to unvested restricted stock					(2,848)		(3,282)		(1,207)		(1,590)
		Net earnings available to common stock		$	190,486	$	201,765	$	79,210	$	95,546
Weighted-average common shares outstanding					94,522		98,551		94,165		98,442
Dilutive effect of outstanding securities (determined using
	treasury stock method)				276		240		293		218
		Weighted-average common shares and potential
			common shares outstanding		94,798		98,791		94,458		98,660
Earnings per common share
		Basic		$	2.02	$	2.05	$	0.84	$	0.97
		Diluted		$	2.01	$	2.04	$	0.84	$	0.97