Contingencies And Commitments (Expected Remediation Cost By Year) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	$ 6
Undiscounted amount due within two year	5
Undiscounted amount due within third year	5
Undiscounted amount due within fourth year	4
Undiscounted amount due within five year	4
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	7
Undiscounted amount due within two year	14
Undiscounted amount due within third year	12
Undiscounted amount due within fourth year	10
Undiscounted amount due within five year	$ 19