Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended			3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Consumers Energy Company [Member]	Sep. 30, 2013 Consumers Energy Company [Member]	Jun. 30, 2013 Consumers Energy Company [Member]	Mar. 31, 2013 Consumers Energy Company [Member]	Dec. 31, 2012 Consumers Energy Company [Member]	Sep. 30, 2012 Consumers Energy Company [Member]	Jun. 30, 2012 Consumers Energy Company [Member]	Mar. 31, 2012 Consumers Energy Company [Member]	Dec. 31, 2013 Consumers Energy Company [Member]	Dec. 31, 2012 Consumers Energy Company [Member]	Dec. 31, 2011 Consumers Energy Company [Member]	Dec. 31, 2013 Internal Revenue Service (IRS) [Member]	May 31, 2012 Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Uncertain tax benefits	$ 4				$ 1				$ 4	$ 1	$ 4	$ 4				$ 1				$ 4	$ 1	$ 4
Net operating loss carryforward																								45
Net income	$ 102	$ 127	$ 81	$ 144	$ 67	$ 149	$ 101	$ 67	$ 454	$ 384	$ 417	$ 119	$ 153	$ 100	$ 162	$ 78	$ 163	$ 122	$ 76	$ 534	$ 439	$ 467	$ (1)