Income Taxes (Reconciliation Of Beginning And Ending Uncertain Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Balance at beginning of period	$ 1	$ 4	$ 4
Reductions for prior year tax positions		(4)	(1)
Additions for prior year tax positions	3	1	1
Balance at end of period	4	1	4
Consumers Energy Company [Member]
Balance at beginning of period	1	4	3
Reductions for prior year tax positions		(4)
Additions for prior year tax positions	3	1	1
Balance at end of period	$ 4	$ 1	$ 4