Schedule II - Valuation and Qualifying Accounts and Reserves (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Uncollectible Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 32	$ 35	$ 25
Charged to Expense	63	53	70
Charged to other Accounts
Deductions	62	56	60
Balance at End of Period	33	32	35
Allowance for Uncollectible Accounts [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	30	33	23
Charged to Expense	63	53	70
Charged to other Accounts
Deductions	62	56	60
Balance at End of Period	31	30	33
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	3	20	19
Charged to Expense			1
Charged to other Accounts		(15)
Deductions	1	2
Balance at End of Period	2	3	20
Deferred Tax Valuation Allowance [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	1	1
Charged to Expense			1
Charged to other Accounts
Deductions
Balance at End of Period	1	1	1
Allowance For Notes Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	5	5	5
Charged to Expense	4	4	4
Charged to other Accounts
Deductions	4	4	4
Balance at End of Period	$ 5	$ 5	$ 5