Financial Instruments (Schedule Of Carrying Amounts And Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets
Securities held to maturity	$ 26	$ 21
Liabilities
Current accounts receivable	13	14
Current notes receivable	223	233
Current portion of long term debt	1,111	974
Current portion of long-term payables	1	1
Carrying Amount
Assets
Long-term receivables	20	22
Notes receivable	2,500	1,857
Securities held to maturity	26	22
Liabilities
Long-term debt	13,062	11,589
Long-term payables	30	27
Fair Value
Assets
Long-term receivables	20	22
Notes receivable	2,652	1,967
Securities held to maturity	26	21
Liabilities
Long-term debt	14,185	11,630
Long-term payables	32	27
Consumers Energy Company
Liabilities
Current accounts receivable	13	14
Current portion of long term debt	202	26
DB SERP note receivable – related party	7	7
Consumers Energy Company \| Carrying Amount
Assets
Long-term receivables	20	22
Notes receivable related party	103	106
Liabilities
Long-term debt	7,250	6,805
Consumers Energy Company \| Fair Value
Assets
Long-term receivables	20	22
Notes receivable related party	103	106
Liabilities
Long-term debt	8,010	6,833
Level 1 \| Fair Value
Liabilities
Long-term debt	1,197	459
Level 2 \| Fair Value
Assets
Securities held to maturity	26	21
Liabilities
Long-term debt	11,048	9,404
Level 2 \| Consumers Energy Company \| Fair Value
Assets
Notes receivable related party	0
Liabilities
Long-term debt	6,070	5,066
Level 3 \| Fair Value
Assets
Long-term receivables	20	22
Notes receivable	2,652	1,967
Liabilities
Long-term debt	1,940	1,767
Long-term payables	32	27
Level 3 \| Consumers Energy Company \| Fair Value
Assets
Long-term receivables	20	22
Notes receivable related party	103	106
Liabilities
Long-term debt	1,940	1,767
EnerBank
Liabilities
Current notes receivable	$ 242	$ 233

Notes Receivable, Related Parties, Fair Value Disclosure

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Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

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Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount, after allowance for credit loss, of financing receivable, classified as current. Includes, but is not limited to, notes and loan receivable.

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Fair value portion of notes payable.

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Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

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Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due within 1 year (or 1 business cycle).

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