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	$	766,848		$	769,440
Less allowance for bad debts	(47,779		)	(51,394		)
	$	719,069		$	718,046

(Thousands of Dollars)	June 30, 2013		Dec. 31, 2012
Inventories
Materials and supplies	$	222,628	$	213,739
Fuel	186,009		189,425
Natural gas	86,253		132,410
	$	494,890	$	535,574

(Thousands of Dollars)	June 30, 2013			Dec. 31, 2012
Property, plant and equipment, net
Electric plant	$	29,017,319		$	28,285,031
Natural gas plant	3,903,127			3,836,335
Common and other property	1,475,534			1,480,558
Plant to be retired (a)	115,466			152,730
Construction work in progress	2,298,899			1,757,189
Total property, plant and equipment	36,810,345			35,511,843
Less accumulated depreciation	(12,344,995		)	(12,048,697		)
Nuclear fuel	2,142,145			2,090,801
Less accumulated amortization	(1,794,084		)	(1,744,599		)
	$	24,813,411		$	23,809,348

^(a)  In 2010, in response to the Clean Air Clean Jobs Act (CACJA), the Colorado Public Utilities Commission (CPUC) approved the early retirement of Cherokee Units 1, 2 and 3, Arapahoe Unit 3 and Valmont Unit 5 between 2011 and 2017.  In 2011, Cherokee Unit 2 was retired and in 2012, Cherokee Unit 1 was retired.  Amounts are presented net of accumulated depreciation.