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Benefit Plans and Other Postretirement Benefits, Pension Benefits (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan      
Pension Benefits [Abstract]      
Total benefit obligation $ 2,500 $ 2,600  
Net benefit cost recognized for financial reporting $ 200 300  
Minimum number of years historical achieved weighted average annual returns are used to determine investment return assumptions (in years) 20 years    
Pension Plans      
Pension Benefits [Abstract]      
Total benefit obligation $ 483,601 467,394 $ 500,690
Net benefit cost recognized for financial reporting $ 17,446 $ 20,303 $ 19,999
Expected average long-term rate of return on assets (as a percent) 6.78% 7.22% 6.90%
Expected average long-term rate of return on assets for next fiscal year (as a percent) 6.80%    
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 100.00% 100.00%  
Pension Plans | Domestic and international equity securities      
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 36.00% 36.00%  
Pension Plans | Long-duration fixed income and interest rate swap securities      
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 31.00% 31.00%  
Pension Plans | Short-to-intermediate fixed income securities      
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 15.00% 12.00%  
Pension Plans | Alternative investments      
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 16.00% 19.00%  
Pension Plans | Cash      
Target Pension Asset Allocations [Abstract]      
Target pension asset allocations (as a percent) 2.00% 2.00%  
Xcel Energy Inc. | Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan      
Pension Benefits [Abstract]      
Total benefit obligation $ 43,500 $ 41,800  
Net benefit cost recognized for financial reporting $ 7,900 $ 9,500