Selected Balance Sheet Data

3 Months Ended

Mar. 31, 2012

Selected Balance Sheet Data [Abstract]

Selected Balance Sheet Data

3.     Selected Balance Sheet Data

(Thousands of Dollars)	March 31, 2012			Dec. 31, 2011
Accounts receivable, net
Accounts receivable	$	67,390		$	70,410
Less allowance for bad debts		(5,274	)		(5,380	)
	$	62,116		$	65,030
Inventories
Materials and supplies	$	18,405		$	17,472
Fuel		5,480			18,103
	$	23,885		$	35,575
Property, plant and equipment, net
Electric plant	$	4,188,034		$	4,142,389
Construction work in progress		180,673			153,672
Total property, plant and equipment		4,368,707			4,296,061
Less accumulated depreciation		(1,721,452	)		(1,701,329	)
	$	2,647,255		$	2,594,732