Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings per share

		Nine months ended September 30,				Three months ended September 30,
		2012		2011		2012		2011
Net earnings		$	283,139	$	176,905	$	107,062	$	60,437
Less: net earnings attributable to unvested restricted stock			(5,150)		(2,551)		(1,912)		(950)
	Net earnings available to common stock	$	277,989	$	174,354	$	105,150	$	59,487
Weighted-average common shares outstanding			100,340		110,665		99,424		106,919
Dilutive effect of outstanding options (determined using
	treasury stock method)		261		245		276		129
	Weighted-average common shares and potential
	common shares outstanding		100,601		110,910		99,700		107,048
Anti-dilutive stock options not included in treasury stock
	method computation		717		2,279		461		2,744