XML 72 R49.htm IDEA: XBRL DOCUMENT v2.4.0.6
Financial Instruments (Schedule Of Investment Securities) (Details) (USD $)
In Millions, unless otherwise specified
9 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Sep. 30, 2012
CMS Energy Common Stock [Member]
Consumers Energy Company [Member]
Dec. 31, 2011
CMS Energy Common Stock [Member]
Consumers Energy Company [Member]
Sep. 30, 2012
Supplemental Executive Retirement Plan [Member]
Sep. 30, 2012
Supplemental Executive Retirement Plan [Member]
Consumers Energy Company [Member]
Sep. 30, 2012
Supplemental Executive Retirement Plan [Member]
Mutual Fund [Member]
Dec. 31, 2011
Supplemental Executive Retirement Plan [Member]
Mutual Fund [Member]
Sep. 30, 2012
Supplemental Executive Retirement Plan [Member]
Mutual Fund [Member]
Consumers Energy Company [Member]
Dec. 31, 2011
Supplemental Executive Retirement Plan [Member]
Mutual Fund [Member]
Consumers Energy Company [Member]
Available for sale - Cost     $ 6 $ 7     $ 124 $ 113 $ 84 $ 74
Available for sale - Unrealized Gains     25 28     4   2  
Available for sale - Fair Value     31 35     128 113 86 74
Held to maturity Debt securities - Cost 8 7                
Held to maturity Debt securities - Unrealized Gains 1                  
Held to maturity Debt securities - Fair Value 9 7                
SERP Contributions         $ 13 $ 9