Income Taxes (Tables)

3 Months Ended

Mar. 31, 2012

Income Taxes [Abstract]

Reconciliation Of Effective Income Tax Rate From Continuing Operations

	Three Months Ended March 31,
	2012					2011
	(millions of dollars)
Income tax at Federal statutory rate	$	29		35.0	%	$	33		35.0	%
Increases (decreases) resulting from:
State income taxes, net of Federal effect		4		4.9			5		5.0
Asset removal costs		(3	)	(3.7	)		(1	)	(0.7	)
Cross-border energy lease investments		(1	)	(1.2	)		(1	)	(1.2	)
Change in estimates and interest related to uncertain and effectively settled tax positions		(13	)	(15.9	)		1		1.2
Investment tax credits		(1	)	(1.2	)		(1	)	(1.2	)
Permanent differences related to deferred compensation		(1	)	(1.2	)		(2	)	(2.2	)
Other, net		—		0.4			—		(0.5	)
Consolidated income tax expense related to continuing operations	$	14		17.1	%	$	34		35.4	%