Contingencies And Commitments (Contingencies And Commitments) (Details) (USD $) In Millions, unless otherwise specified					9 Months Ended			9 Months Ended		1 Months Ended	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Consumers Energy Company [Member]	Dec. 31, 2013 Consumers Energy Company [Member]	Sep. 30, 2014 Bay Harbor [Member]	Oct. 31, 2010 Bay Harbor [Member]	Sep. 30, 2014 CERCLA Liability [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Manufactured Gas Plant [Member] Consumers Energy Company [Member] item	Sep. 30, 2014 Electric Utility [Member] NREPA [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Electric Utility [Member] EPA NOV [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Electric Utility [Member] EPA NOV [Member] Consumers Energy Company [Member] item	Sep. 30, 2014 Gas Utility [Member] NREPA [Member] Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Environmental remediation permit renewal term					5 years
Demand for payment by USEPA						$ 7
Increase in liability due to change in estimates					15
Cumulative environmental charge					245
Accrual for environmental loss contingencies					63		3	117	4			1
Discounted projected costs rate					4.34%			2.57%
Remaining undiscounted obligation amount					82			132
Foreign government tax claim on sale	142
Remediation and other response activity costs, minimum							3		4
Remediation and other response activity costs. maximum							9		6			3
Number of boilers alleged to exceed emission limits											14
Alleged number of facilities in violation											3
Number of projects affected by alleged violations											10
Environmental mitigation projects, required investment										7.7
Litigation settlement, gross										2.75
Number of former MGPs								23
Regulatory assets	$ 1,447	$ 1,530	$ 1,447	$ 1,530				$ 147
Authorized recovery, collection period								10 years
Accrual for environmental loss contingencies, inflation rate					1.00%			2.50%