SEGMENT INFORMATION - Average Assets for Segments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total assets	$ 4,663.8	$ 4,816.4
Operating segments | Bedding Products
Segment Reporting Information [Line Items]
Total assets	756.7	816.9
Operating segments | Specialized Products
Segment Reporting Information [Line Items]
Total assets	301.7	346.4
Operating segments | Furniture, Flooring & Textile Products
Segment Reporting Information [Line Items]
Total assets	355.4	383.2
Operating segments | Average current liabilities included in segment numbers above
Segment Reporting Information [Line Items]
Total assets	629.4	735.3
Unallocated assets
Segment Reporting Information [Line Items]
Total assets	2,592.4	2,662.7
Difference between average assets and period-end balance sheet
Segment Reporting Information [Line Items]
Total assets	$ 28.2	$ (128.1)