Business Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment									2
Segment information [Abstract]
Total assets	$ 3,061.8				$ 2,715.4				$ 3,061.8	$ 2,715.4
Total property, plant and equipment, net	435.8				420.8				435.8	420.8
Operating lease right-of-use assets	245.4				0.0				245.4	0.0
Net sales	871.3	$ 821.0	$ 722.8	$ 690.9	676.1	$ 729.5	$ 659.9	$ 637.4	3,106.0	2,702.9	$ 2,700.6
Inter-segment royalty expense (income)									0.0	0.0	0.0
Gross profit	386.4	360.6	313.4	281.8	283.2	300.0	272.8	264.7	1,342.2	1,120.7	1,121.0
Operating income (loss)	84.6	$ 120.6	$ 81.0	$ 60.5	57.9	$ 84.7	$ 58.0	$ 55.7	346.7	256.3	295.5
Income (loss) from continuing operations before income taxes									265.5	165.0	215.4
Depreciation and amortization									116.5	111.9	94.0
Capital expenditures									88.2	73.6	66.6
Bedding sales
Segment information [Abstract]
Net sales										2,455.3	2,473.4
Other sales
Segment information [Abstract]
Net sales										247.6	227.2
United States
Segment information [Abstract]
Total property, plant and equipment, net	366.4				350.7				366.4	350.7
Operating lease right-of-use assets	198.3				0.0				198.3	0.0
Net sales											1,954.2
Canada
Segment information [Abstract]
Total property, plant and equipment, net	17.5				19.1				17.5	19.1
Operating lease right-of-use assets	4.9				0.0				4.9	0.0
Net sales											219.6
Other International
Segment information [Abstract]
Total property, plant and equipment, net	51.9				51.0				51.9	51.0
Operating lease right-of-use assets	42.2				0.0				42.2	0.0
Net sales											526.8
Total International
Segment information [Abstract]
Total property, plant and equipment, net	69.4				70.1				69.4	70.1
Operating lease right-of-use assets	47.1				0.0				47.1	0.0
Net sales									793.7	774.0	746.4
Operating Segments
Segment information [Abstract]
Net sales									3,106.0	2,702.9
Operating Segments | Bedding sales
Segment information [Abstract]
Net sales									2,835.3	2,455.3
Operating Segments | Other sales
Segment information [Abstract]
Net sales									270.7	247.6
Operating Segments | United States
Segment information [Abstract]
Net sales									2,312.3	1,928.9
Operating Segments | Canada
Segment information [Abstract]
Net sales									221.0	207.3
Operating Segments | Other International
Segment information [Abstract]
Net sales										566.7
Operating Segments | North America
Segment information [Abstract]
Total property, plant and equipment, net	328.9				317.5				328.9	317.5
Operating lease right-of-use assets	202.0				0.0				202.0	0.0
Net sales									2,533.3	2,136.2	2,173.8
Inter-segment royalty expense (income)									4.5	3.1	5.5
Gross profit									1,035.2	823.4	844.7
Operating income (loss)									344.8	250.0	273.2
Income (loss) from continuing operations before income taxes									337.0	241.1	276.0
Depreciation and amortization									64.4	59.0	51.4
Capital expenditures									62.1	52.7	39.9
Operating Segments | North America | Bedding sales
Segment information [Abstract]
Net sales									2,379.6	2,002.1	2,051.8
Operating Segments | North America | Other sales
Segment information [Abstract]
Net sales									153.7	134.1	122.0
Operating Segments | North America | United States
Segment information [Abstract]
Net sales									2,312.3	1,928.9
Operating Segments | North America | Canada
Segment information [Abstract]
Net sales									221.0	207.3
Operating Segments | International
Segment information [Abstract]
Total property, plant and equipment, net	51.8				51.1				51.8	51.1
Operating lease right-of-use assets	42.2				0.0				42.2	0.0
Net sales									572.7	566.7	526.8
Inter-segment royalty expense (income)									(4.5)	(3.1)	(5.5)
Gross profit									307.0	297.3	276.3
Operating income (loss)									115.4	107.5	112.0
Income (loss) from continuing operations before income taxes									109.7	101.0	104.5
Depreciation and amortization									13.7	13.5	14.1
Capital expenditures									11.6	14.0	9.0
Operating Segments | International | Bedding sales
Segment information [Abstract]
Net sales									455.7	453.2	421.6
Operating Segments | International | Other sales
Segment information [Abstract]
Net sales									117.0	113.5	105.2
Corporate
Segment information [Abstract]
Total property, plant and equipment, net	55.1				52.2				55.1	52.2
Operating lease right-of-use assets	1.2				0.0				1.2	0.0
Net sales									0.0	0.0	0.0
Inter-segment royalty expense (income)									0.0	0.0	0.0
Gross profit									0.0	0.0	0.0
Operating income (loss)									(113.5)	(101.2)	(89.7)
Income (loss) from continuing operations before income taxes									(181.2)	(177.1)	(165.1)
Depreciation and amortization									38.4	39.4	28.5
Capital expenditures									14.5	6.9	17.7
Corporate | Bedding sales
Segment information [Abstract]
Net sales									0.0	0.0	0.0
Corporate | Other sales
Segment information [Abstract]
Net sales									0.0	0.0	0.0
Inter-segment eliminations
Segment information [Abstract]
Net sales									(4.1)	(3.9)	(4.8)
Inter-segment eliminations | North America
Segment information [Abstract]
Net sales									3.4	3.4	3.8
Inter-segment eliminations | International
Segment information [Abstract]
Net sales									0.7	0.5	$ 1.0
Continuing Operations | Operating Segments | North America
Segment information [Abstract]
Total assets	3,142.9				2,788.1				3,142.9	2,788.1
Continuing Operations | Operating Segments | International
Segment information [Abstract]
Total assets	615.3				604.8				615.3	604.8
Continuing Operations | Corporate
Segment information [Abstract]
Total assets	477.1				569.0				477.1	569.0
Continuing Operations | Inter-segment eliminations
Segment information [Abstract]
Total assets	$ (1,173.5)				$ (1,246.5)				$ (1,173.5)	$ (1,246.5)