Financings And Capitalization (Narrative) (Details) (USD $)		9 Months Ended	1 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended	18 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 CMS Energy [Member]	Jun. 30, 2014 Consumers Energy Company [Member]	Sep. 30, 2014 Consumers Energy Company [Member]	Sep. 30, 2014 Consumers Energy Company [Member] Commercial Paper [Member]	Sep. 30, 2014 Short Term Secured Borrowing Accounts Receivable Sales Program [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Continuous Equity Program [Member]	Sep. 30, 2014 Revolving Credit Facilities December 20, 2018 [Member] CMS Energy [Member]		Sep. 30, 2014 Revolving Credit Facilities December 20, 2018 [Member] Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Maximum allowed short term securities outstanding under FERC Authorization			$ 800,000,000
Amount of accounts receivable eligible for transfer						250,000,000
Average short-term borrowings						15,000,000
Weighted average annual interest rate						0.85%
Amount of Facility								550,000,000	[1]	650,000,000	[2]
Short-term debt, authorized borrowings					500,000,000
Short-term borrowings outstanding					0
Limitation on payment of stock dividends	3,700,000,000
Unrestricted retained earnings				735,000,000
Common stock dividends from Consumers		375,000,000
Aggregate sales price of an equity offering program							50,000,000
Accounts receivable sales facility, remaining borrowing capacity						250,000,000		548,000,000	[1]	650,000,000	[2]
Maximum limitation on outstanding securities			$ 1,900,000,000
Expiration date of authorizations				June 30, 2016

[1] Obligations under this facility are secured by Consumers common stock.

[2] Obligations under this facility are secured by FMBs of Consumers.