Regulatory Matters - MISO Return on Equity Complaints (Details) - FERC [Member]	Sep. 30, 2016	Sep. 28, 2016
Return on Equity Complaint 1 [Member]
Loss Contingencies [Line Items]
Requested Return on Equity Filed with the FERC by Third Party		9.15%
FERC Authorized Return on Common Equity	10.32%
Return on Equity Complaint 2 [Member]
Loss Contingencies [Line Items]
Requested Return on Equity Filed with the FERC by Third Party	8.67%
Proposed Return on Equity by Federal Administrative Law Judge	9.70%
Incentive Adder [Member]
Loss Contingencies [Line Items]
FERC Approved Incentive Adder for Participation in Regional Transmission Organization	0.50