Related Party Transactions - Consumers (Tables) (Consumers Energy Company [Member])

12 Months Ended

Dec. 31, 2012

Consumers Energy Company [Member]

Schedule of Related Party Transactions, by Related Party Table

In Millions
Description	Related Party	2012			2011			2010
Purchases of capacity and energy	Affiliates of CMS Enterprises		$	86		$	81		$	84