Segment Results (Tables)

9 Months Ended

Sep. 30, 2020

Segment Reporting [Abstract]

Schedule of Net Sales

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2020		2019		2020		2019
Net sales
Mineral Fiber	$	187.3	$	218.6	$	542.9	$	629.4
Architectural Specialties		59.0		58.5		155.3		161.8
Total net sales	$	246.3	$	277.1	$	698.2	$	791.2

Schedule of Segment Operating Income (Loss)

	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2020		2019			2020		2019
Segment operating income (loss)
Mineral Fiber	$	58.1	$	103.5		$	173.7	$	230.5
Architectural Specialties		9.1		11.6			20.9		30.3
Unallocated Corporate		5.1		(1.8	)		16.1		(5.6	)
Total consolidated operating income	$	72.3	$	113.3		$	210.7	$	255.2

Reconciliation of Total Consolidated Operating Income to Earnings Before Income Taxes

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2020			2019			2020			2019
Total consolidated operating income	$	72.3		$	113.3		$	210.7		$	255.2
Interest expense		6.1			11.7			18.7			31.6
Other non-operating (income) expense, net		(3.2	)		(5.1	)		361.8			(16.0	)
Earnings (loss) from continuing operations before income taxes	$	69.4		$	106.7		$	(169.8	)	$	239.6

Reconciliation of Total Segment Assets to Total Consolidated Assets

	September 30, 2020		December 31, 2019
Segment assets
Mineral Fiber	$	1,110.9	$	1,139.9
Architectural Specialties		258.8		161.8
Unallocated Corporate		264.0		191.6
Total consolidated assets	$	1,633.7	$	1,493.3