DEBT (Tables)

12 Months Ended

Dec. 31, 2017

Debt Instruments [Abstract]

Schedule of long-term debt

	December 31,
	2017			2016
Notes payable:	($ in millions)
Variable-rate Senior Term Loan Facility, due 2022 and 2020, respectively, (3.57% and 2.77% at December 31, 2017 and 2016, respectively)	$	1,323.4		$	1,282.5
Variable-rate Sumitomo Credit Facility, due 2018 (2.27% at December 31, 2016)	—			590.0
Variable-rate Recovery Zone bonds, due 2024-2035 (3.27% and 2.47% at December 31, 2017 and 2016, respectively)	103.0			103.0
Variable-rate Go Zone bonds, due 2024 (3.27% and 2.47% at December 31, 2017 and 2016, respectively)	50.0			50.0
Variable-rate Industrial development and environmental improvement obligations, due 2025 (1.27% and 0.25% at December 31, 2017 and 2016, respectively)	2.9			2.9
9.75%, due 2023	720.0			720.0
10.00%, due 2025	500.0			500.0
5.50%, due 2022	200.0			200.0
5.125%, due 2027	500.0			—
7.23%, SunBelt Notes due 2013-2017	—			12.2
Senior Revolving Credit Facility	20.0			—
Receivables Financing Agreement	249.7			210.0
Capital lease obligations	3.7			3.9
Total notes payable	3,672.7			3,674.5
Deferred debt issuance costs	(32.6		)	(28.5		)
Interest rate swaps	(28.1		)	(28.4		)
Total debt	3,612.0			3,617.6
Amounts due within one year	0.7			80.5
Total long-term debt	$	3,611.3		$	3,537.1