Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 2,400
Performance guarantees outstanding	75
Present value abandonment obligation	$ 31
Workforce Subject to Collective Bargaining Arrangements [Member]
Long-term Purchase Commitment [Line Items]
Employees covered by collective bargaining agreement	56.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member]
Long-term Purchase Commitment [Line Items]
Employees covered by collective bargaining agreement	19.00%
Capital Purchase Obligation [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 58
IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1,774
Maximum indemnification limit	$ 17
IPL [Member] | Workforce Subject to Collective Bargaining Arrangements [Member]
Long-term Purchase Commitment [Line Items]
Employees covered by collective bargaining agreement	65.00%
IPL [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member]
Long-term Purchase Commitment [Line Items]
Employees covered by collective bargaining agreement	46.00%
IPL [Member] | Capital Purchase Obligation [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 3
WPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 611
WPL [Member] | Workforce Subject to Collective Bargaining Arrangements [Member]
Long-term Purchase Commitment [Line Items]
Employees covered by collective bargaining agreement	81.00%
WPL [Member] | Capital Purchase Obligation [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 55
Environmental Issue [Member] | IPL [Member]
Long-term Purchase Commitment [Line Items]
Damages awarded	6
Environmental Issue [Member] | WPL [Member]
Long-term Purchase Commitment [Line Items]
Damages awarded	$ 7