Selected Balance Sheet Data

6 Months Ended

Jun. 30, 2012

Selected Balance Sheet Data [Abstract]

Selected Balance Sheet Data

3.  Selected Balance Sheet Data

(Thousands of Dollars)	June 30, 2012			Dec. 31, 2011
Accounts receivable, net
Accounts receivable	$	80,727		$	70,410
Less allowance for bad debts		(5,376	)		(5,380	)
	$	75,351		$	65,030
Inventories
Materials and supplies	$	18,547		$	17,472
Fuel		6,643			18,103
	$	25,190		$	35,575
Property, plant and equipment, net
Electric plant	$	4,304,461		$	4,142,389
Construction work in progress		154,484			153,672
Total property, plant and equipment		4,458,945			4,296,061
Less accumulated depreciation		(1,738,170	)		(1,701,329	)
	$	2,720,775		$	2,594,732