Summary of Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Jan. 01, 2022	Jan. 02, 2021
Numerator:
Numerator for both basic and diluted EPS attributable to HNI Corporation net income	$ 123.9	$ 59.8	$ 41.9
Denominators:
Denominator for basic EPS weighted- average common shares outstanding (in shares)	41.7	43.4	42.7
Potentially dilutive shares from stock-based compensation plans (in shares)	0.5	0.5	0.3
Denominator for diluted EPS (in shares)	42.2	44.0	43.0
Earnings per share - basic (in dollars per share)	$ 2.97	$ 1.38	$ 0.98
Earnings per share - diluted (in dollars per share)	$ 2.94	$ 1.36	$ 0.98
Stock Compensation Plan
Denominators:
Common stock equivalents excluded because their inclusion would be anti-dilutive (in shares)	2.0	1.6	3.1