AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ

Quarterly report pursuant to Section 13 or 15(d)

ACQUISITION OF AK STEEL - Consideration (Details)

v3.20.2
ACQUISITION OF AK STEEL - Consideration (Details)
$ / shares in Units, $ in Millions
Mar. 13, 2020
USD ($)
$ / shares
shares
Sep. 30, 2020
shares
Jun. 30, 2020
shares
Mar. 31, 2020
shares
Dec. 31, 2019
shares
Sep. 30, 2019
shares
Jun. 30, 2019
shares
Mar. 31, 2019
shares
Dec. 31, 2018
shares
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of Cliffs common shares issued for AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ outstanding common stock $ 617.6 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Common shares, outstanding (in shares) | shares Ìý 399,229,917 Ìý Ìý 270,084,005 Ìý Ìý Ìý Ìý
AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ Holding Corporation [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of Cliffs common shares issued for AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ outstanding common stock 617.6 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of debt included in consideration 913.6 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Combination, Consideration Transferred $ 1,535.1 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Common shares, outstanding (in shares) | shares 316,900,000 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition, Shares Exchange Ratio 0.400 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Shares of Cliffs common shares issued to AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ stockholders | shares 126,800,000 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Price per share of Cliffs common shares | $ / shares $ 4.87 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Credit Facility | AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ Holding Corporation [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of debt included in consideration $ 590.0 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
7.50% 2023 AK Senior Notes [Member] | AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ Holding Corporation [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of debt included in consideration 323.6 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Share-based Payment Arrangement [Member] | AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ Holding Corporation [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of Cliffs common shares issued for AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ outstanding common stock 3.9 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Common Stock [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Common shares, outstanding (in shares) | shares Ìý 399,200,000 399,200,000 398,600,000 270,100,000 270,100,000 270,000,000.0 282,800,000 292,600,000
Common Stock [Member] | AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ Holding Corporation [Member] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Business Acquisition [Line Items] Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý
Fair value of Cliffs common shares issued for AK AGÕæÈËÆ½Ì¨AGÕæÈËÊÔÍæ outstanding common stock $ 617.6 Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý