Condensed Consolidating Financial Information - Statement of Cash Flows (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities		$ (69.1)	$ 51.5	[1]	$ 38.2	[1]
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment		(83.0)	(31.8)	[1]	(21.9)	[1]
Proceeds from sale of property, plant and equipment		0.1	14.4	[1]	1.0	[1]
Intercompany transactions		0.0	0.0		0.0
Net cash (used in) investing activities		(82.9)	(17.4)	[1]	(20.9)	[1]
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities		120.1	1.3	[1]	1.2	[1]
Repayments under revolving credit facilities		(96.8)	(1.3)	[1]	(1.2)	[1]
Issuance of common stock		0.4	0.4	[1]	0.0	[1]
Intercompany transactions		0.0	0.0		0.0
Net cash provided by financing activities		23.7	0.4	[1]	0.0	[1]
CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		(128.3)	34.5	[1]	17.3	[1]
Cash, cash equivalents and restricted cash, beginning of year	[1]	168.0	133.5		116.2
Cash, cash equivalents and restricted cash, end of year		39.7	168.0	[1]	133.5	[1]
Reportable Legal Entities [Member] | The Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities		(53.0)	(34.5)		(63.4)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment		(4.4)	(10.9)		(1.4)
Proceeds from sale of property, plant and equipment		0.0	0.0		0.0
Intercompany transactions		21.6	75.6		27.8
Net cash (used in) investing activities		17.2	64.7		26.4
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities		120.1	1.3		1.2
Repayments under revolving credit facilities		(96.8)	(1.3)		(1.2)
Issuance of common stock		0.4	0.4
Intercompany transactions		(52.1)	(3.1)		15.4
Net cash provided by financing activities		(28.4)	(2.7)		15.4
CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		(64.2)	27.5		(21.6)
Cash, cash equivalents and restricted cash, beginning of year		64.3	36.8		58.4
Cash, cash equivalents and restricted cash, end of year		0.1	64.3		36.8
Reportable Legal Entities [Member] | Combined Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities		(19.5)	(7.0)		19.0
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment		(65.1)	(8.1)		(7.8)
Proceeds from sale of property, plant and equipment		0.0	0.9		0.0
Intercompany transactions		54.7	6.2		(15.4)
Net cash (used in) investing activities		(10.4)	(1.0)		(23.2)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities		0.0	0.0		0.0
Repayments under revolving credit facilities		0.0	0.0		0.0
Issuance of common stock		0.0	0.0
Intercompany transactions		30.0	8.2		7.5
Net cash provided by financing activities		30.0	8.2		7.5
CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		0.1	0.2		3.3
Cash, cash equivalents and restricted cash, beginning of year		0.7	0.5		(2.8)
Cash, cash equivalents and restricted cash, end of year		0.8	0.7		0.5
Reportable Legal Entities [Member] | Combined Non-Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities		3.4	96.0		82.6
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment		(13.5)	(12.8)		(12.7)
Proceeds from sale of property, plant and equipment		0.1	13.5		1.0
Intercompany transactions		2.2	(7.6)		(0.9)
Net cash (used in) investing activities		(11.2)	(6.9)		(12.6)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities		0.0	0.0		0.0
Repayments under revolving credit facilities		0.0	0.0		0.0
Issuance of common stock		0.0	0.0
Intercompany transactions		(56.4)	(82.3)		(34.4)
Net cash provided by financing activities		(56.4)	(82.3)		(34.4)
CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		(64.2)	6.8		35.6
Cash, cash equivalents and restricted cash, beginning of year		103.0	96.2		60.6
Cash, cash equivalents and restricted cash, end of year		38.8	103.0		96.2
Consolidating Adjustments [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities		0.0	(3.0)		0.0
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment		0.0	0.0		0.0
Proceeds from sale of property, plant and equipment		0.0	0.0		0.0
Intercompany transactions		(78.5)	(74.2)		(11.5)
Net cash (used in) investing activities		(78.5)	(74.2)		(11.5)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities		0.0	0.0		0.0
Repayments under revolving credit facilities		0.0	0.0		0.0
Issuance of common stock		0.0	0.0
Intercompany transactions		78.5	77.2		11.5
Net cash provided by financing activities		78.5	77.2		11.5
CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		0.0	0.0		0.0
Cash, cash equivalents and restricted cash, beginning of year		0.0	0.0		0.0
Cash, cash equivalents and restricted cash, end of year		$ 0.0	$ 0.0		$ 0.0

[1] As adjusted due to the adoption of ASU 2016-18 "Statement of Cash Flows (Topic 230) Restricted Cash."