Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tax effect on benefit obligation	$ 5	$ 6	$ 8
Tax effect, net unrealized gains on derivatives	0	0	0
Tax effect on net unrealized gains (losses) on investments during the period	1	1	0
DTE Electric
Tax effect on transfer of benefit obligations			18
Tax effect on net unrealized gains (losses) on investments during the period	$ 1	$ 0	$ 0