Schedule I - Condensed Financial Information of Registrant (Statements of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income	$ 454	$ 384	$ 417
Deferred income taxes	271	226	169
Accounts and notes receivable	(120)	(147)	119
Accounts payable	6	(5)	30
Other current and non-current assets and liabilities	(106)	(70)	(7)
Net cash provided by operating activities	1,421	1,241	1,169
Net cash used in investing activities	(1,532)	(1,350)	(1,058)
Proceeds from issuance of long-term debt	1,025	1,650	375
Issuance of common stock	36	30	29
Retirement of long-term debt	(741)	(1,527)	(413)
Redemption of preferred stock	(7)
Increase (decrease) in notes payable	60	110
Net cash provided by (used in) financing activities	190	41	(199)
Net Increase (Decrease) in Cash and Cash Equivalents	79	(68)	(86)
Cash and Cash Equivalents, Beginning of Period	93	161	247
Cash and Cash Equivalents, End of Period	172	93	161
CMS Energy [Member]
Net Income	452	382	415
Equity earnings of subsidiaries	(566)	(477)	(510)
Dividends received from subsidiaries	435	401	474
Deferred income taxes	48	(25)	14
Accounts and notes receivable	(3)	2	(1)
Accounts payable	2
Accrued taxes	48	9	(97)
Other current and non-current assets and liabilities	18	(14)	12
Net cash provided by operating activities	434	278	307
Investment in subsidiaries	(150)	(151)	(125)
Net cash used in investing activities	(150)	(151)	(125)
Proceeds from issuance of long-term debt	275	575	375
Issuance of common stock	36	30	29
Retirement of long-term debt	(275)	(463)	(376)
Payment of common stock dividends	(271)	(252)	(211)
Debt issuance costs and financing fees	(4)	(4)	(6)
Increase (decrease) in notes payable	(47)	(11)	7
Net cash provided by (used in) financing activities	(286)	(125)	(182)
Net Increase (Decrease) in Cash and Cash Equivalents	(2)	2
Cash and Cash Equivalents, Beginning of Period	2
Cash and Cash Equivalents, End of Period		$ 2