Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2016
Minimum [Member] | EnerBank [Member]
Significant Accounting Policies [Line Items]
Same as cash, fee recognition period	3 months
Authorized contractor, fee recognition period	1 year
Maximum [Member] | Consumers Energy Company [Member]
Significant Accounting Policies [Line Items]
Financial incentive as percentage of energy optimization program spending	15.00%
Energy optimization spending limit	2.00%
Maximum [Member] | EnerBank [Member]
Significant Accounting Policies [Line Items]
Same as cash, fee recognition period	24 months
Authorized contractor, fee recognition period	12 years