Statements Of Consolidated Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 3,033	$ (81)	$ 293
Other comprehensive income (loss):
Changes in pension and OPEB, net of tax	684	181	(35)
Changes in foreign currency translation	(2)	3	0
Changes in derivative financial instruments, net of tax	69	2	0
Total other comprehensive income (loss)	751	186	(35)
Comprehensive income	3,784	105	258
Comprehensive income attributable to noncontrolling interests	(45)	(41)	0
Comprehensive income attributable to Cliffs shareholders	$ 3,739	$ 64	$ 258