Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net earnings	$ 185.9	$ 154.8	$ 104.7
Adjustments to reconcile earnings to net cash provided by operating activities:
Depreciation and amortization	79.4	89.2	89.2
Loss (gain) on disposal of discontinued operations	19.3	74.1	(0.1)
Deferred income taxes	(3.8)	(12.3)	51.0
Share-based compensation	14.0	10.2	12.4
Equity earnings from joint venture	(74.9)	(67.0)	(73.1)
Separation costs			34.5
Loss on interest rate swap			10.7
U.S. pension (credit) expense	(26.3)	(4.5)	15.0
Non-cash foreign currency translation on intercompany loans	0.8	(2.6)	(3.6)
Other, non-cash adjustments, net	2.1	2.2	0.8
Changes in operating assets and liabilities:
Receivables	13.2	(37.1)	(23.9)
Inventories	(8.9)	3.6	(7.0)
Other current assets	9.4	2.2	7.1
Other noncurrent assets	(5.5)	(1.6)	(9.9)
Accounts payable and accrued expenses	5.4	(20.0)	(82.1)
Income taxes payable	7.5	(18.8)	(49.3)
Other long-term liabilities	(14.4)	(1.2)	(22.0)
Other, net		(0.8)	(5.1)
Net cash provided by operating activities	203.2	170.4	49.3
Cash flows from investing activities:
Purchases of property, plant and equipment	(71.9)	(89.7)	(104.2)
Return of investment from joint venture	141.7	69.1	86.9
Cash paid for acquisitions	(22.2)	(31.2)
Proceeds from (payment of) company-owned life insurance, net	2.0	(2.4)
Payments of proceeds from Knauf to investment in joint venture	(70.0)
Cash consideration received from Knauf	330.0
Other investing activities			0.3
Net cash provided by (used for) investing activities	309.6	(54.2)	(17.0)
Cash flows from financing activities:
Proceeds from revolving credit facility and other short-term debt		103.0	90.0
Payments of revolving credit facility and other short-term debt		(103.0)	(90.0)
Proceeds from long-term debt			363.5
Payments of long-term debt	(32.5)	(25.0)	(434.1)
Financing costs		(0.6)	(8.1)
Dividend paid	(8.6)
Proceeds from exercised stock options	18.4	3.3	0.7
Cash transferred to Armstrong Flooring, Inc.			(9.1)
Proceeds from company-owned life insurance loans, net			2.0
Payment for treasury stock acquired	(306.6)	(80.4)	(43.8)
Net cash (used for) financing activities	(329.3)	(102.7)	(128.9)
Effect of exchange rate changes on cash and cash equivalents	(7.4)	4.2	(6.3)
Net increase (decrease) in cash and cash equivalents	176.1	17.7	(102.9)
Cash and cash equivalents at beginning of year	159.6	141.9	244.8
Cash and cash equivalents at end of year	335.7	159.6	141.9
Cash and cash equivalents at end of year from discontinued operations	10.0
Cash and cash equivalents	325.7	159.6	141.9
Supplemental Cash Flow Disclosures:
Interest paid	29.9	30.7	33.4
Income taxes paid, net	51.6	32.1	33.7
Amounts in accounts payable for capital expenditures	$ 1.9	$ 2.6	$ 4.4