Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net Income	$ 682	$ 659	$ 462
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	992	933	881
Deferred income taxes and investment tax credits	150	182	417
Bad debt expense	67	54	49
Other non‑cash operating activities and reconciling adjustments	(58)	22	82
Postretirement benefits contributions	(10)	(252)	(12)
Cash provided by (used in) changes in assets and liabilities
Accounts and notes receivable and accrued revenue	45	15	(66)
Inventories	44	14	(46)
Accounts payable and accrued rate refunds	(69)	22	49
Other current and non‑current assets and liabilities	(53)	54	(111)
Net cash provided by operating activities	1,790	1,703	1,705
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under finance lease)	(2,104)	(2,074)	(1,665)
Proceeds from DB SERP investments	0	146	0
Increase in EnerBank notes receivable	(401)	(307)	(138)
Purchase of notes receivable by EnerBank	(343)	(225)	0
Proceeds from sale of EnerBank notes receivable	67	0	50
Proceeds from sale of transmission equipment	97	0	0
Cost to retire property and other investing activities	(132)	(146)	(115)
Net cash used in investing activities	(2,816)	(2,606)	(1,868)
Cash Flows from Financing Activities
Proceeds from issuance of debt	2,151	2,767	1,633
Retirement of debt	(1,285)	(1,870)	(980)
Increase in EnerBank certificates of deposit	631	513	47
Decrease in notes payable	(7)	(73)	(228)
Issuance of common stock	12	41	83
Payment of dividends on common and preferred stock	(436)	(407)	(377)
Debt prepayment costs	(8)	(36)	(22)
Other financing costs	(50)	(61)	(46)
Net cash provided by financing activities	1,008	874	110
Net Decrease in Cash and Cash Equivalents, Including Restricted Amounts	(18)	(29)	(53)
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	175	204	257
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	157	175	204
Cash transactions
Interest paid (net of amounts capitalized)	498	458	418
Income taxes paid (refunds received), net	(58)	(123)	5
Non‑cash transactions
Capital expenditures not paid	170	158	172
Other assets placed under finance lease	0	0	3
Consumers Energy Company
Cash Flows from Operating Activities
Net Income	743	705	632
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	975	921	872
Deferred income taxes and investment tax credits	37	123	163
Bad debt expense			29
Other non‑cash operating activities and reconciling adjustments	(32)	13	59
Postretirement benefits contributions	(7)	(242)	(8)
Cash provided by (used in) changes in assets and liabilities
Accounts and notes receivable and accrued revenue	8	(26)	(63)
Inventories	40	15	(45)
Accounts payable and accrued rate refunds	(63)	12	43
Other current and non‑current assets and liabilities	(129)	(101)	33
Net cash provided by operating activities	1,601	1,449	1,715
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under finance lease)	(2,085)	(1,822)	(1,632)
Proceeds from DB SERP investments	0	106	0
DB SERP investment in note receivable – related party	0	(106)	0
Proceeds from sale of transmission equipment	77	0	0
Cost to retire property and other investing activities	(129)	(149)	(119)
Net cash used in investing activities	(2,137)	(1,971)	(1,751)
Cash Flows from Financing Activities
Proceeds from issuance of debt	993	2,106	834
Retirement of debt	(541)	(1,193)	(555)
Decrease in notes payable	(7)	(73)	(228)
Stockholder contribution	675	250	450
Payment of dividends on common and preferred stock	(594)	(533)	(524)
Debt prepayment costs	(8)	(20)	(4)
Other financing costs	(10)	(24)	(24)
Net cash provided by financing activities	508	513	(51)
Net Decrease in Cash and Cash Equivalents, Including Restricted Amounts	(28)	(9)	(87)
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	56	65	152
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	28	56	65
Cash transactions
Interest paid (net of amounts capitalized)	279	287	266
Income taxes paid (refunds received), net	132	156	(1)
Non‑cash transactions
Capital expenditures not paid	160	143	160
Other assets placed under finance lease	$ 0	$ 0	$ 3