Net Income Per Common Share (Tables)

3 Months Ended

Mar. 31, 2012

Net Income Per Common Share [Abstract]

Computation of net income per common share

	Three Months Ended March 31,
(Thousands of dollars except per share data)	2012			2011
Basic
Average common shares outstanding		102,070,349			104,991,014
Net income	$	100,216		$	68,316
Less net income allocated to unvested restricted shares		(782	)		(670	)
Net income allocated to common shares	$	99,434		$	67,646
Basic net income per common share	$	.97		$	.64
Diluted
Average common shares outstanding		102,070,349			104,991,014
Stock options and other contingently issuable shares (1)		2,387,739			2,371,655
Average common shares outstanding assuming dilution		104,458,088			107,362,669
Net income	$	100,216		$	68,316
Less net income allocated to unvested restricted shares assuming dilution		(768	)		(662	)
Net income allocated to common shares assuming dilution	$	99,448		$	67,654
Diluted net income per common share	$	.95		$	.63

⁽¹⁾  Stock options and other contingently issuable shares excluded 54,675 shares for the three months ended March 31, 2011 due to their anti-dilutive effect. There were no options excluded due to their anti-dilutive effect for the three months ended March 31, 2012.