Earnings Per Share

3 Months Ended

Mar. 31, 2012

Earnings per share of common stock [Abstract]

Earnings Per Share Text Block

3.Earnings Per Share

Basic earnings per share are computed using the weighted average number of common shares outstanding for each period presented.  Diluted earnings per share are computed using the weighted average number of common shares outstanding plus the potential effects of the assumed exercise of stock options, and payment of estimated stock awards from other stock-based compensation plans that are outstanding, at the end of each period presented.  Diluted earnings per share are calculated as follows:

		Three Months Ended
		March 31,
Thousands, except per share amounts			2012		2011
Net income		$	40,607	$	40,773
Average common shares outstanding - basic			26,781		26,670
	Additional shares for stock-based compensation plans(1)		81		54
Average common shares outstanding - diluted			26,862		26,724
Earnings per share of common stock - basic		$	1.52	$	1.53
Earnings per share of common stock - diluted		$	1.51	$	1.53
(1)Additional shares not included in diluted earnings per share calculation
because of antidilutive impact			1,010		2,150