Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2011

Regulatory Assets and Liabilities (Tables) [Abstract]

Regulatory assets and liabilities

Our regulatory assets and liabilities as of December 31 consist of:

	2011		2010
	(Millions of Dollars)
Regulatory Assets
Deferred unrecognized pension costs	$	647.8	$	542.6
Deferred income tax related	121.2		89.9
Escrowed electric transmission costs	118.3		138.0
Deferred unrecognized OPEB costs	102.9		85.7
Deferred plant related -- capital lease	73.2		77.1
Deferred environmental costs	48.5		56.7
Other, net	153.8		154.5
Total regulatory assets	$	1,265.7	$	1,144.5
Regulatory Liabilities
Deferred cost of removal obligations	$	728.2	$	723.9
Escrowed bad debt costs	69.0		18.5
Other, net	118.7		156.7
Total regulatory liabilities	$	915.9	$	899.1