CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 847.0	$ 1,038.0	$ 3,022.0	$ 3,541.0
Cost of sales	764.0	810.0	2,401.0	2,594.0
Gross margin	83.0	228.0	621.0	947.0
Selling, general and administrative expenses	49.0	56.0	154.0	176.0
Other operating—net	(4.0)	(30.0)	8.0	(63.0)
Total other operating costs and expenses	45.0	26.0	162.0	113.0
Equity in earnings (losses) of operating affiliate	2.0	(14.0)	8.0	(6.0)
Operating earnings	40.0	188.0	467.0	828.0
Interest expense	48.0	63.0	141.0	182.0
Interest income	0.0	(4.0)	(18.0)	(12.0)
Other non-operating—net	1.0	(4.0)	(2.0)	(7.0)
(Loss) earnings before income taxes	(9.0)	133.0	346.0	665.0
Income tax provision (benefit)	(13.0)	19.0	33.0	113.0
Net earnings	4.0	114.0	313.0	552.0
Less: Net earnings attributable to noncontrolling interest	32.0	49.0	83.0	114.0
Net (loss) earnings attributable to common stockholders	$ (28.0)	$ 65.0	$ 230.0	$ 438.0
Net earnings per share attributable to common stockholders:
Basic (in dollars per share)	$ (0.13)	$ 0.29	$ 1.07	$ 1.98
Diluted (in dollars per share)	$ (0.13)	$ 0.29	$ 1.07	$ 1.97
Weighted average common shares outstanding:
Basic (in shares)	213.9	219.0	215.0	221.2
Diluted (in shares)	213.9	220.7	215.3	222.5
Dividends declared per common share (in dollars per share)	$ 0.30	$ 0.30	$ 0.90