Net Income Per Common Share (Tables)

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

Computation of net income per common share

(Thousands of dollars except per share data)	Three Months Ended March 31,
	2015			2014
Basic
Average common shares outstanding	92,740,059			98,833,210
Net income	$	131,404		$	115,457
Less net income allocated to unvested restricted shares	(475		)	(523		)
Net income allocated to common shares	$	130,929		$	114,934
Basic net income per common share	$	1.41		$	1.16
Diluted
Average common shares outstanding	92,740,059			98,833,210
Stock options and other contingently issuable shares (1)	2,005,070			2,025,671
Average common shares outstanding assuming dilution	94,745,129			100,858,881
Net income	$	131,404		$	115,457
Less net income allocated to unvested restricted shares
assuming dilution	(467		)	(515		)
Net income allocated to common shares assuming
dilution	$	130,937		$	114,942
Diluted net income per common share	$	1.38		$	1.14

⁽¹⁾  Stock options and other contingently issuable shares excluded 12,414 and 2,932 shares due to their anti-dilutive effect for the three months ended March 31, 2015 and 2014, respectively.