Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities
Net income	$ 454	$ 384	$ 417
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	628	598	546
Deferred income taxes and investment tax credit	268	227	167
Postretirement benefits expense	144	187	161
Bad debt expense	67	57	74
Other non-cash operating activities	22	16	33
Postretirement benefits contributions	(229)	(72)	(323)
Proceeds from government grant	69
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(120)	(147)	119
Decrease (increase) in inventories	202	104	(14)
Increase (decrease) in accounts payable	6	(5)	30
Increase (decrease) in accrued expenses	16	(38)	(34)
Other current and non-current assets and liabilities	(106)	(70)	(7)
Net cash provided by operating activities	1,421	1,241	1,169
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,325)	(1,227)	(882)
Cost to retire property	(56)	(49)	(54)
Increase in EnerBank loans receivable	(139)	(63)	(100)
Other investing activities	(12)	(11)	(22)
Net cash used in investing activities	(1,532)	(1,350)	(1,058)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	1,025	1,650	375
Proceeds from (retirements of) EnerBank notes, net	125	65	98
Issuance of common stock	36	30	29
Retirement of long-term debt	(741)	(1,527)	(413)
Payment of DOE liability			(43)
Payment of common and preferred stock dividends	273	252	211
Redemption of preferred stock	(7)
Payment of capital lease obligations and other financing costs	(35)	(35)	(34)
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, Including Assets Held for Sale	79	(68)	(88)
Decrease (Increase) in Cash and Cash Equivalents Included in Assets Held for Sale			2
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
Cash transactions
Interest paid (net of amounts capitalized)	382	377	397
Income taxes paid	34	19	27
Non-Cash Transactions
Capital expenditures not paid	176	110	92
Other assets placed under capital lease	6	9	4
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	534	439	467
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	622	592	542
Deferred income taxes and investment tax credit	164	150	161
Postretirement benefits expense	142	184	158
Bad debt expense	63	53	70
Other non-cash operating activities	12	14	16
Postretirement benefits contributions	(222)	(68)	(315)
Proceeds from government grant	69
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(116)	(145)	112
Decrease (increase) in inventories	205	107	(17)
Increase (decrease) in accounts payable	14	7	43
Increase (decrease) in accrued expenses	(27)	51	74
Other current and non-current assets and liabilities	(109)	(31)	12
Net cash provided by operating activities	1,351	1,353	1,323
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,320)	(1,222)	(876)
Cost to retire property	(56)	(49)	(56)
Other investing activities	(11)	(8)	(19)
Net cash used in investing activities	(1,387)	(1,279)	(951)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	750	1,075
Retirement of long-term debt	(466)	(1,064)	(37)
Payment of DOE liability			(43)
Payment of common and preferred stock dividends	408	395	376
Redemption of preferred stock	(7)
Stockholder contribution	150	150	125
Payment of capital lease obligations and other financing costs	(30)	(30)	(27)
Increase (decrease) in notes payable	60	110
Net cash provided by (used in) financing activities	49	(154)	(358)
Net Increase (Decrease) in Cash and Cash Equivalents	13	(80)	14
Cash and Cash Equivalents, Beginning of Period	5	85	71
Cash and Cash Equivalents, End of Period	18	5	85
Cash transactions
Interest paid (net of amounts capitalized)	236	224	253
Income taxes paid	225	63	8
Non-Cash Transactions
Capital expenditures not paid	176	110	92
Other assets placed under capital lease	$ 6	$ 9	$ 4