Revenue - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue from External Customer [Line Items]
Allowance for doubtful accounts receivable write-offs	$ 25
DTE Electric
Revenue from External Customer [Line Items]
Allowance for doubtful accounts receivable write-offs	$ 14
Other | Power and Industrial Projects
Revenue from External Customer [Line Items]
Payment terms	30 days