Restructuring, Impairment, and Loss on Divestiture - Schedule of Restructuring and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2025	Sep. 28, 2024	Sep. 27, 2025	Sep. 28, 2024
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1.0	$ 3.4	$ 11.6	$ 6.2
Facility closure and consolidation costs | Workplace furnishings
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.3	1.8	1.9	2.5
Divestiture of HNI India | Workplace furnishings
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.3	0.0	6.1	0.0
Divestiture of HNI India | General Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0	0.0	0.6	0.0
Exit costs | Workplace furnishings
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.5	0.5	3.1	2.6
Reorganization costs | Residential building products
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0.0	$ 1.1	$ 0.0	$ 1.1