Selected Balance Sheet Data

9 Months Ended

Sep. 30, 2012

Selected Balance Sheet Data [Abstract]

Selected Balance Sheet Data

3.   Selected Balance Sheet Data

(Thousands of Dollars)	Sept. 30, 2012			Dec. 31, 2011
Accounts receivable, net
Accounts receivable	$	89,009		$	70,410
Less allowance for bad debts		(4,938	)		(5,380	)
	$	84,071		$	65,030

(Thousands of Dollars)	Sept. 30, 2012		Dec. 31, 2011
Inventories
Materials and supplies	$	19,022	$	17,472
Fuel		12,952		18,103
	$	31,974	$	35,575

(Thousands of Dollars)	Sept. 30, 2012			Dec. 31, 2011
Property, plant and equipment, net
Electric plant	$	4,344,849		$	4,142,389
Construction work in progress		199,459			153,672
Total property, plant and equipment		4,544,308			4,296,061
Less accumulated depreciation		(1,758,904	)		(1,701,329	)
	$	2,785,404		$	2,594,732