Statements Of Unaudited Condensed Consolidated Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 356	$ 601	$ 314	$ 1,415
Other comprehensive income (loss):
Changes in pension and OPEB, net of tax	(26)	0	(53)	1
Changes in derivative financial instruments, net of tax	18	(55)	(134)	41
Changes in foreign currency translation	0	(2)	0	(2)
Total other comprehensive income (loss)	(8)	(57)	(187)	40
Comprehensive income	348	544	127	1,455
Comprehensive income attributable to noncontrolling interests	(9)	(5)	(24)	(18)
Comprehensive income attributable to Cliffs shareholders	$ 339	$ 539	$ 103	$ 1,437