Summarized Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2011

Summarized Quarterly Financial Data (Unaudited) [Abstract]

Summarized Quarterly Financial Data (Unaudited)

14.	Summarized Quarterly Financial Data (Unaudited)

	Quarter Ended
(Thousands of Dollars)	March 31, 2011		June 30, 2011		Sept. 30, 2011		Dec. 31, 2011
Operating revenues	$	238,108	$	198,850	$	224,468	$	214,364
Operating income		29,897		20,115		39,032		18,464
Net income		14,643		8,478		19,973		7,912

	Quarter Ended
(Thousands of Dollars)	March 31, 2010		June 30, 2010		Sept. 30, 2010		Dec. 31, 2010
Operating revenues	$	224,769	$	179,597	$	211,068	$	211,857
Operating income		28,867		8,994		33,131		17,829
Net income		13,544		2,679		17,624		8,902

- Definition

The entire disclosure for the quarterly financial data in the annual financial statements. The disclosure may include a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income or loss before extraordinary items and earnings per share data. It also includes an indication if the information in the note is unaudited, comments on the aggregate effect of year-end adjustments, and an explanation of matters or transactions that affect comparability or are pertinent to an understanding of the information furnished.

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