Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities
Net income	$ 164	$ 202
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	238	222
Deferred income taxes and investment tax credit	68	99
Other non-cash operating activities	21	42
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	16	(48)
Decrease (increase) in inventories	274	378
Increase (decrease) in accounts payable and accrued refunds	(48)	(36)
Other current and non-current assets and liabilities	(101)	(99)
Net cash provided by operating activities	632	760
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(407)	(348)
Increase in EnerBank notes receivable	(16)	(29)
Other investing activities	(28)	(45)
Net cash used in investing activities	(451)	(422)
Cash Flows from Financing Activities
Proceeds from issuance of debt	30	100
Proceeds from EnerBank certificates of deposit, net	14	40
Issuance of common stock	63	4
Retirement of long-term debt	(30)	(11)
Payment of dividends on common stock	(86)	(80)
Decrease in notes payable	(249)	(60)
Payment of capital lease obligations and other financing costs	(12)	(16)
Net cash used in financing activities	(270)	(23)
Net Increase (Decrease) in Cash and Cash Equivalents	(89)	315
Cash and Cash Equivalents, Beginning of Period	266	207
Cash and Cash Equivalents, End of Period	177	522
Non-Cash Transactions
Capital expenditures not paid	173	117
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	172	215
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	237	220
Deferred income taxes and investment tax credit	62	39
Other non-cash operating activities	17	40
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	33	(43)
Decrease (increase) in inventories	270	374
Increase (decrease) in accounts payable and accrued refunds	(42)	(32)
Other current and non-current assets and liabilities	(84)	(27)
Net cash provided by operating activities	665	786
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(406)	(345)
Other investing activities	(27)	(38)
Net cash used in investing activities	(433)	(383)
Cash Flows from Financing Activities
Retirement of long-term debt		(11)
Payment of dividends on common stock	(155)	(122)
Stockholder contribution	150	150
Decrease in notes payable	(249)	(60)
Payment of capital lease obligations and other financing costs	(1)	(6)
Net cash used in financing activities	(255)	(49)
Net Increase (Decrease) in Cash and Cash Equivalents	(23)	354
Cash and Cash Equivalents, Beginning of Period	50	71
Cash and Cash Equivalents, End of Period	27	425
Non-Cash Transactions
Capital expenditures not paid	$ 154	$ 117