Significant Accounting Policies (Uncollectible Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Uncollectible expense	$ 55	$ 105	$ 106
DTE Electric
Accounts, Notes, Loans and Financing Receivable [Line Items]
Uncollectible expense	$ 36	$ 62	$ 65