Financings and Capitalization (Narrative) (Details) (USD $)	12 Months Ended					12 Months Ended	31 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Consumers Energy Company [Member]	Dec. 31, 2012 Consumers Energy Company [Member]	Jul. 31, 2013 Consumers Energy Company [Member] $4.16 Series [Member]	Dec. 31, 2013 Short-Term Borrowings [Member] Consumers Energy Company [Member]	Dec. 31, 2013 Continuous Equity Program [Member]	Dec. 31, 2013 Senior Notes 5.5% Due June 2029 [Member]	Dec. 31, 2013 Senior Notes 5.5% Due June 2029 [Member]
Financing And Capitalization [Line Items]
Maximum allowed short term securities outstanding under FERC Authorization	$ 500,000,000		$ 500,000,000
Short-term securites, remaining availability under FERC Authorization	200,000,000		200,000,000
Maximum allowed long-term securites outstanding under FERC Authorization	1,900,000,000		1,900,000,000
Long-term securities, remaining availability under FERC Authorization	800,000,000		800,000,000
Amount of accounts receivable eligible for transfer						250,000,000
Outstanding balance of revolving accounts receivable sales program						170,000,000
Average short-term borrowings						10,000,000
Weighted average annual interest rate						0.90%
Trigger price as a percentage of conversion price									130.00%
Number of trading days, adjusted trigger price contingencies were met								20 days	20 days
Number of trading days								30 days	30 days
Principal converted								17,000,000
Convertible debt, interest rate								5.50%
Debt conversion, Ratio denominator								1,000
Debt Conversion, Converted Instrument, Amount per denominator amount								1,968
Shares issued upon debt conversion								605,531
Debt conversion, Cash paid upon settlement								17,000,000
Limitation on payment of stock dividends	3,500,000,000
Unrestricted retained earnings			662,000,000
Common stock dividends from Consumers	406,000,000
Common stock, shares authorized	350,000,000	350,000,000	125,000,000	125,000,000
Par value of Common Stock	$ 0.01
Shares of Preferred Stock authorized	10,000,000		7,500,000	7,500,000
Par value of Preferred Stock	$ 0.01		$ 100	$ 100	$ 4.16
Aggregate sales price of an equity offering program							50,000,000
Redemption price per share					$ 103.25
Redemption price					$ 7,000,000
Preferred shares outstanding					68,451