CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues
Electric	$ 865,239	$ 805,554	$ 797,562
Gas	287,605	263,394	318,335
Other	1,675	1,394	1,419
Total Revenues	1,154,519	1,070,342	1,117,316
Operating Expenses
Cost of sales	479,546	395,434	494,559
Operating, general and administrative	285,569	269,966	267,160
Mountain States Transmission Intertie impairment	0	24,039	0
Property and other taxes	105,540	97,674	89,122
Depreciation	112,831	106,044	100,926
Total Operating Expenses	983,486	893,157	951,767
Operating Income	171,033	177,185	165,549
Interest Expense	(70,486)	(65,062)	(66,859)
Other Income	7,737	4,372	3,931
Income Before Income Taxes	108,284	116,495	102,621
Income Tax Expense	(14,301)	(18,089)	(10,065)
Net Income	$ 93,983	$ 98,406	$ 92,556
Average Common Shares Outstanding	38,144,852	36,847,427	36,258,463
Basic Earnings per Average Common Share	$ 2.46	$ 2.67	$ 2.55
Diluted Earnings per Average Common Share	$ 2.46	$ 2.66	$ 2.53