Consolidated Statements Of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Revenue	$ 1,953	$ 1,829
Operating Expenses
Fuel for electric generation	132	117
Purchased and interchange power	382	333
Purchased power - related parties	19	22
Cost of gas sold	381	336
Maintenance and other operating expenses	310	290
Depreciation and amortization	279	262
General taxes	87	81
Total operating expenses	1,590	1,441
Operating Income	363	388
Other Income (Expense)
Interest income	2	5
Allowance for equity funds used during construction	1	2
Income from equity method investees	3	4
Nonoperating retirement benefits, net	24	3
Other income	1	2
Other expense	(2)	(2)
Total other income	29	14
Interest Charges
Interest on long-term debt	100	100
Other interest expense	11	8
Allowance for borrowed funds used during construction		(1)
Total interest charges	111	107
Income Before Income Taxes	281	295
Income Tax Expense	40	96
Net Income	$ 241	$ 199
Basic Earnings Per Average Common Share	$ 0.86	$ 0.71
Diluted Earnings Per Average Common Share	0.86	0.71
Dividends Declared Per Common Share	$ 0.3575	$ 0.3325
Consumers Energy Company [Member]
Operating Revenue	$ 1,855	$ 1,737
Operating Expenses
Fuel for electric generation	102	89
Purchased and interchange power	378	331
Purchased power - related parties	20	22
Cost of gas sold	377	332
Maintenance and other operating expenses	282	265
Depreciation and amortization	277	260
General taxes	85	79
Total operating expenses	1,521	1,378
Operating Income	334	359
Other Income (Expense)
Interest income	2	4
Allowance for equity funds used during construction	1	2
Nonoperating retirement benefits, net	22	3
Other income	1	14
Other expense	(2)	(2)
Total other income	24	21
Interest Charges
Interest on long-term debt	67	66
Other interest expense	5	3
Allowance for borrowed funds used during construction		(1)
Total interest charges	72	68
Income Before Income Taxes	286	312
Income Tax Expense	44	101
Net Income	$ 242	$ 211