Income Taxes (Significant Components Of Income Tax Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Federal		$ 1	$ 2
State and Local	34	21	24
Total Current Income Tax Expense	34	22	26
Federal, deferred income taxes	248	205	207
State and Local, deferred income taxes	23	21	11
MCIT law change, deferred income taxes			(49)
Total Deferred Income Tax Expense	271	226	169
Deferred income tax credit	(3)	(3)	(4)
Tax Expense	302	245	191
Consumers Energy Company [Member]
Federal	137	110	74
State and Local	45	37	32
Total Current Income Tax Expense	182	147	106
Federal, deferred income taxes	147	134	159
State and Local, deferred income taxes	20	19	6
Total Deferred Income Tax Expense	167	153	165
Deferred income tax credit	(3)	(3)	(4)
Tax Expense	$ 346	$ 297	$ 267