Equity Incentive Program (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Share-Based Compensation Recognized Period Costs

The following table summarizes the stock-based compensation expense recognized by the Company for the periods presented:

	Years Ended December 31,
(in millions)	2022		2021		2020
Pre-tax stock-based compensation expense
Cost of goods sold	$	1.6	$	1.6	$	1.7
Research and development expenses	5.6		5.5		6.2
Selling and administrative expenses	21.4		25.0		9.4
Total pre-tax stock-based compensation expense	28.6		32.1		17.3
Tax benefit	4.4		5.1		—
Total stock-based compensation expense, net of tax	$	24.2	$	27.0	$	17.3

Schedule of Black-Scholes Option-Pricing Assumptions

The fair value of stock options granted by the Company was estimated on the date of grant using a Black-Scholes option-pricing model based on the assumptions shown in the table below.

	Years Ended December 31,
	2022	2021			2020
Risk-free interest rate	0.85%	0.06%			0.11%	to	1.42%
Dividend yield	—%	—%			—%
Expected life (years)	4.5	4.5			4.3	to	4.5
Volatility	34.3%	36.0%			38.8%	to	40.6%
Fair value at date of grant	$6.29	$6.14	to	$6.31	$4.78	to	$5.95

Schedule of SSAR and Stock Options Activity

The following table summarizes the Company's stock-settled stock appreciation right ("SSAR") and stock option activity for the year ended December 31, 2022.

	SSARs						Stock Options
	Number of Shares	Weighted-Average Exercise Price		Aggregate Intrinsic Value		Weighted-Average Remaining Contractual Term (Years)	Number of Shares	Weighted-Average Exercise Price		Aggregate Intrinsic Value		Weighted-Average Remaining Contractual Term (Years)
(in millions, except share and per share amounts)
Outstanding at December 31, 2021	375,964	$	23.16				3,478,438	$	15.04
Granted	—	—					216,813	21.14
Exercised	(36,759)	21.77					(850,844)	11.97
Forfeited	—	—					(69,873)	20.63
Expired	(115,641)	22.14					(71,110)	17.86
Outstanding at December 31, 2022	223,564	$	23.92	$	—	0.1	2,703,424	$	16.28	$	3.2	2.8
Exercisable at December 31, 2022	223,564	$	23.92	$	—	0.1	2,204,948	$	15.63	$	3.2	2.3

Schedule of Other Share-based Compensation, Activity

Other information regarding the exercise of SSARs and stock options is listed below:

	Years Ended December 31,
(in millions)	2022		2021		2020
SSARs
Aggregate intrinsic value of SSARs exercised	$	0.1	$	0.1	$	—
Stock Options
Cash received by Knowles for exercise of stock options	$	7.5	$	25.6	$	1.8
Aggregate intrinsic value of stock options exercised	6.0		6.6		0.4
Tax benefit from stock options exercised	1.2		1.2		—

Schedule of Restricted Stock Units Award Activity

The following table summarizes the Company's RSU activity for the year ended December 31, 2022:

	Share units	Weighted-average grant date fair value
Unvested at December 31, 2021	1,778,639	$	18.89
Granted	1,235,845	20.38
Vested (1)	(838,222)	18.30
Forfeited	(295,741)	20.24
Unvested at December 31, 2022	1,880,521	$	19.96

Schedule of Nonvested Performance-Based Units Activity

The following table summarizes the Company's PSU activity for the year ended December 31, 2022:

	Share units	Weighted-average grant date fair value
Unvested at December 31, 2021	766,466	$	21.28
Granted	294,935	29.92
Vested (1)	(227,812)	18.44
Forfeited	—	—
Unvested at December 31, 2022	833,589	$	25.12

(1) The number of PSUs vested includes shares that the Company withheld on behalf of employees to satisfy statutory tax withholding requirements.