Selected Balance Sheet Data

6 Months Ended

Jun. 30, 2013

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Data

Selected Balance Sheet Data

(Thousands of Dollars)	June 30, 2013			Dec. 31, 2012
Accounts receivable, net
Accounts receivable	$	76,967		$	66,789
Less allowance for bad debts	(4,500		)	(4,722		)
	$	72,467		$	62,067

(Thousands of Dollars)	June 30, 2013		Dec. 31, 2012
Inventories
Materials and supplies	$	19,225	$	18,129
Fuel	9,010		13,208
	$	28,235	$	31,337

(Thousands of Dollars)	June 30, 2013			Dec. 31, 2012
Property, plant and equipment, net
Electric plant	$	4,631,722		$	4,379,208
Construction work in progress	223,206			237,136
Total property, plant and equipment	4,854,928			4,616,344
Less accumulated depreciation	(1,795,054		)	(1,754,588		)
	$	3,059,874		$	2,861,756