Knowles (KN) 10-K 20 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Knowles Corp
Entity Central Index Key	1,587,523
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,477,000,000
Entity Common Stock, Shares Outstanding		89,491,800
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

CONSOLIDATED STATEMENTS OF EARN

CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues		$ 744.2	$ 755.7	$ 753.6
Cost of goods sold		452.5	458	465.8
Tangible Asset Impairment Charges		1.4	0.3	3.3
Restructuring charges - cost of goods sold		4	1.5	2.7
Gross profit		286.3	295.9	281.8
Research and development expenses		93.4	92	83.2
Selling and administrative expenses		126.3	149.9	149.7
Total impairment charges		19.9	0.2	2.3
Restructuring charges		6.2	8.6	11.6
Operating expenses		245.8	250.7	246.8
Operating earnings		40.5	45.2	35
Interest expense, net		20.6	20.4	12.7
Other expense (income), net		0.5	(3.3)	1.7
Earnings before income taxes and discontinued operations	[1]	19.4	28.1	20.6
Provision for income taxes		12.9	8.3	3.2
Earnings from continuing operations		6.5	19.8	17.4
Earnings (loss) from discontinued operations, net		61.8	(62.1)	(251.2)
Net earnings (loss)		$ 68.3	$ (42.3)	$ (233.8)
Earnings per share:
Per Share - Basic		$ 0.07	$ 0.22	$ 0.20
Per Share - Diluted		0.07	0.22	0.20
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share		0.68	(0.69)	(2.89)
Per Share - Basic		0.76	(0.48)	(2.69)
Per Share - Diluted		$ 0.75	$ (0.47)	$ (2.69)
Weighted-average common shares outstanding:
Basic (in shares)	[2]	89,329,794	88,667,098	86,802,828
Diluted (in shares)	[2]	90,490,007	89,182,967	86,992,254
[1]	Years Ended December 31,(in millions)2017 2016 2015Revenues: Audio$637.4 $661.9 $654.3Precision Devices106.8 93.8 99.3Total consolidated revenues$744.2 $755.7 $753.6 Earnings from continuing operations before interest and income taxes: Audio$76.1 $88.8 $84.7Precision Devices19.2 12.4 5.4Total segments95.3 101.2 90.1Corporate expense / other55.3 52.7 56.8Interest expense, net20.6 20.4 12.7Earnings before income taxes and discontinued operations19.4 28.1 20.6Provision for income taxes12.9 8.3 3.2Earnings from continuing operations$6.5 $19.8 $17.4 Depreciation and amortization: Audio$45.2 $61.4 $65.1Precision Devices5.6 4.3 4.6Corporate3.0 3.3 2.7Total$53.8 $69.0 $72.4 Capital expenditures: Audio$43.6 $27.8 $26.5Precision Devices5.4 3.1 4.0Corporate0.5 1.3 6.3Total$49.5 $32.2 $36.8 Research and development: Audio$89.0 $89.2 $79.5Precision Devices4.2 2.7 3.7Corporate0.2 0.1 —Total$93.4 $92.0 $83.2
[2]	Years Ended December 31, 2017 2016 2015Revenues$744.2 $755.7 $753.6Cost of goods sold452.5 458.0 465.8Impairment charges1.4 0.3 3.3Restructuring charges - cost of goods sold4.0 1.5 2.7Gross profit286.3 295.9 281.8Research and development expenses93.4 92.0 83.2Selling and administrative expenses126.3 149.9 149.7Impairment charges19.9 0.2 2.3Restructuring charges6.2 8.6 11.6Operating expenses245.8 250.7 246.8Operating earnings40.5 45.2 35.0Interest expense, net20.6 20.4 12.7Other expense (income), net0.5 (3.3) 1.7Earnings before income taxes and discontinued operations19.4 28.1 20.6Provision for income taxes12.9 8.3 3.2Earnings from continuing operations6.519.8 17.4Earnings (loss) from discontinued operations, net61.8 (62.1) (251.2)Net earnings (loss)$68.3 $(42.3) $(233.8) Earnings per share from continuing operations: Basic$0.07 $0.22 $0.20Diluted$0.07 $0.22 $0.20 Earnings (loss) per share from discontinued operations: Basic$0.69 $(0.70) $(2.89)Diluted$0.68 $(0.69) $(2.89) Net earnings (loss) per share: Basic$0.76 $(0.48) $(2.69)Diluted$0.75 $(0.47) $(2.69) Weighted-average common shares outstanding: Basic89,329,79488,667,098 86,802,828Diluted90,490,00789,182,967 86,992,254

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 68.3	$ (42.3)	$ (233.8)
Other comprehensive earnings (loss), net of tax
Foreign currency translation	27.1	0.8	(71.7)
Employee benefit plans:
Actuarial gains (losses) arising during period	0.7	(5.6)	(0.6)
Amortization or settlement of actuarial losses and prior service costs	0.6	0.5	0.8
Net change in employee benefit plans	1.3	(5.1)	0.2
Changes in fair value of cash flow hedges:
Unrealized net gains (losses) arising during period	3.4	(2.5)	(1.4)
Net losses reclassified into earnings	0.3	0.9	0
Total cash flow hedges	3.7	(1.6)	(1.4)
Other comprehensive earnings (loss), net of tax	32.1	(5.9)	(72.9)
Comprehensive earnings (loss)	$ 100.4	$ (48.2)	$ (306.7)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 111.7	$ 63.4
Receivables, net of allowances of $0.7 and $1.5	137.7	126.4
Inventories, net	125.6	90.8
Prepaid and other current assets	19.9	10.3
Total current assets	394.9	290.9
Property, plant, and equipment, net	183	172.9
Goodwill	884.9	871.6
Intangible assets, net	53.5	73.8
Other assets and deferred charges	31.8	25.7
Disposal Group, Including Discontinued Operation, Assets	1.7	80.1
Total assets	1,549.8	1,515
Current liabilities:
Current maturities of long-term debt	0	9.7
Accounts payable	85.6	65.5
Accrued compensation and employee benefits	31.2	31.4
Other accrued expenses	28.2	22.4
Federal and other taxes on income	6.6	3.2
Total current liabilities	151.6	132.2
Long-term debt	192.6	288.5
Deferred income taxes	0	21.6
Other liabilities	67.9	40.6
Disposal Group, Including Discontinued Operation, Liabilities	5.6	23.7
Commitments and contingencies (Note 14)
Stockholders' equity:
Preferred stock - $0.01 par value; 10,000,000 shares authorized; none issued	0	0
Common stock - $0.01 par value; 400,000,000 shares authorized; 89,491,471 and 88,737,284 shares issued and outstanding at December 31, 2017 and 2016, respectively	0.9	0.9
Additional paid-in capital	1,523.1	1,499.8
Accumulated deficit	(291.9)	(360.2)
Accumulated other comprehensive loss	(100)	(132.1)
Total stockholders' equity	1,132.1	1,008.4
Total equity	1,132.1	1,008.4
Total liabilities and stockholders' equity	$ 1,549.8	$ 1,515

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Allowance for doubtful accounts receivable	$ 0.7	$ 1.5
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	89,491,471	88,737,284

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Audience, Inc.Additional Paid-In Capital
Balance at Dec. 31, 2014	$ 1,236.1	$ 0.9	$ 1,372.6	$ (84.1)	$ (53.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(233.8)			(233.8)
Other Comprehensive Income (Loss), Net of Tax	(72.9)				(72.9)
Stock-based compensation expense	16.5		16.5
Stock-based restructuring charges	1.4					$ 1.4
Tax on restricted stock unit vesting	(2.2)		(2.2)
Cash consideration paid to Audience shareholders and equity award holders	61.6					$ 61.6
Balance at Dec. 31, 2015	1,006.7	0.9	1,449.9	(317.9)	(126.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(42.3)			(42.3)
Other Comprehensive Income (Loss), Net of Tax	(5.9)				(5.9)
Stock-based compensation expense	21.5		21.5
Tax on restricted stock unit vesting	(1.5)		(1.5)
Purchase of convertible note hedges	(44.5)
Issuance of warrants	39.1		39.1
Equity component of the convertible notes issuance, net	35.3		35.3
Balance at Dec. 31, 2016	1,008.4	0.9	1,499.8	(360.2)	(132.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	68.3			68.3
Other Comprehensive Income (Loss), Net of Tax	32.1				32.1
Stock-based compensation expense	25.1		25.1
Tax on restricted stock unit vesting	(5.1)		(5.1)
Common stock issued for exercise of stock options	3.3		3.3
Balance at Dec. 31, 2017	$ 1,132.1	$ 0.9	$ 1,523.1	$ (291.9)	$ (100)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Operating Activities
Net earnings (loss)	$ 68.3	$ (42.3)	$ (233.8)
Adjustments to reconcile net earnings (loss) to cash from operating activities:
Depreciation and amortization	57.3	73.7	135.7
Stock-based compensation	25.1	21.5	16.5
Impairment of intangibles	16.2	0	144.7
Non-cash interest expense and amortization of debt issuance costs	7.6	5.6	0.8
Impairment charges on fixed and other assets	5.5	0.9	56.5
Gain (Loss) on Disposition of Business	(62.3)	25.6	0
Deferred income taxes	(30.1)	4	(25)
Other, net	4.9	(3.2)	(1.1)
Cash effect of changes in assets and liabilities (excluding effects of foreign exchange):
Receivables, net	2.4	35.9	45.2
Inventories, net	(34)	21.9	11.7
Prepaid and other current assets	(8.4)	(1.2)	1.6
Accounts payable	4.9	(26.6)	(42.7)
Accrued compensation and employee benefits	(0.9)	(0.7)	0.3
Other accrued expenses	7.3	(9.6)	(14.9)
Accrued taxes	0.9	5.3	(12.9)
Other non-current assets and non-current liabilities	28.2	(3.3)	(4.2)
Net cash provided by operating activities	92.9	107.5	78.4
Investing Activities
Proceeds from the sale of business	123.1	40.6	0
Proceeds from the sale of property, plant, and equipment	0.5	2	0.5
Proceeds from the sale of investments	0	2	4
Additions to property, plant, and equipment	(51.6)	(38.7)	(63.1)
Acquisitions of business (net of cash acquired)	(2.5)	0	(35.1)
Capitalized patent defense costs	0	0	(1)
Purchase of intellectual property license	0	0	(0.5)
Net cash provided by (used in) investing activities	69.5	5.9	(95.2)
Financing Activities
Payments under revolving credit facility	(185)	(132)	(85)
Borrowings under revolving credit facility	190.7	32	130
Principal payments on term loan debt	(118.5)	(166.5)	(15)
Proceeds from issuance of convertible senior notes	0	172.5	0
Proceeds from issuance of warrants	0	39.1	0
Purchase of convertible note hedges	0	(44.5)	0
Debt issuance costs	(1.7)	(6.7)	(0.3)
Payments of capital lease obligations	(1.6)	(2.3)	(1.4)
Tax on restricted stock unit vesting	(5.1)	(1.5)	(2.2)
Net proceeds from exercise of stock-based awards	3.3	0	0
Net cash (used in) provided by financing activities	(117.9)	(109.9)	26.1
Effect of exchange rate changes on cash and cash equivalents	1	(0.6)	(1.2)
Net increase in cash and cash equivalents	45.5	2.9	8.1
Cash and cash equivalents at beginning of period	63.4	61.3	52.7
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	0	(2.8)	(2)
Supplemental information - cash paid during the year for:
Income taxes	13.1	4.2	19.3
Interest	$ 11.3	$ 12.2	$ 11.2

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Background - Knowles Corporation (NYSE:KN) is a market leader and global supplier of advanced micro-acoustic, audio processing, and precision device solutions, serving the mobile consumer electronics, communications, medical, military, aerospace, and industrial markets. The Company uses its leading position in micro-electro-mechanical systems ("MEMS") microphones and strong capabilities in audio processing technologies to optimize audio systems and improve the user experience in mobile, ear, and Internet of Things ("IoT") applications. Knowles is also the leader in acoustics components used in hearing aids and has a strong position in high-end capacitors. The Company's focus on its customers, combined with its unique technology, proprietary manufacturing techniques, rigorous testing, and global scale, enable the Company to deliver innovative solutions that optimize the user experience. References to "Knowles," "the Company," "we," "our," and "us" refer to Knowles Corporation and its consolidated subsidiaries. In January 2017, the Company changed its allocation of resources and its internal reporting structure to facilitate delivering growth in its core business. Given these changes, beginning in January 2017, the Company's two reportable segments are as follows: • Audio Segment Our Audio group designs and manufactures innovative audio products, including microphones and balanced armature speakers, signal processing technologies, and software and algorithms used in applications that serve the mobile, ear, and IoT markets. Locations include the sales, support, and engineering facilities in North America, Europe, and Asia, as well as the manufacturing facilities in Asia. • Precision Devices ("PD") Segment Our PD group specializes in the design and delivery of highly engineered capacitors and radio frequency devices ("RF") for technically demanding applications. Our devices are used in applications including power supplies, radar, medical implants, and satellites, serving the industrial, defense, aerospace, medical, and telecommunications markets. Locations include the sales, support, engineering, and manufacturing facilities in North America, Europe, and Asia. Financial reporting under this new structure is included within this report on Form 10-K and historical financial segment information has been recast to conform to this new presentation within our financial statements. See Note 17. Segment Information for additional information related to the Company’s segments. The Company was spun-off from Dover Corporation ("Dover" or "Former Parent") in 2014 (the "Separation") and our common stock began trading under the ticker symbol “KN” on the New York Stock Exchange (the “NYSE”) on March 3, 2014. On November 28, 2017, the Company completed its sale of the high-end oscillators business ("Timing Device Business"). On July 7, 2016, the Company completed its sale of the speaker and receiver product line (“Speaker and Receiver Product Line”). In accordance with Accounting Standards Codification ("ASC") 205-20, Presentation of Financial Statements - Discontinued Operations, the results of operations and related assets and liabilities for the Timing Device Business and Speaker and Receiver Product Line have been reclassified as discontinued operations for all periods presented. See Note 2. Disposed and Discontinued Operations for additional information related to the transactions. Financial Statement Presentation - The Consolidated Financial Statements included in this Annual Report on Form 10-K are presented in conformity with U.S. generally accepted accounting principles ("U.S. GAAP"). Use of Estimates - The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements and disclosures. These estimates may be adjusted due to changes in future economic, industry, or customer financial conditions, as well as changes in technology or demand. Estimates are used in accounting for, among other items, allowances for doubtful accounts receivable, inventory reserves, restructuring reserves, warranty reserves, pension and post-retirement plans, stock-based compensation, corporate allocations, useful lives for depreciation and amortization of long-lived assets, future cash flows associated with impairment testing for goodwill, indefinite-lived intangible assets and other long-lived assets, deferred tax assets, uncertain income tax positions, changes in tax laws, and contingencies. Actual results may ultimately differ from estimates, although management does not believe such differences would materially affect the financial statements in any individual year. Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the Consolidated Financial Statements in the period that they are determined. Cash and Cash Equivalents - Cash and cash equivalents include cash on hand, demand deposits, and temporary cash investments with original maturities less than three months. Allowance for Doubtful Accounts – The Company maintains allowances for estimated losses as a result of customers' inability to make required payments. Management evaluates the aging of the accounts receivable balances, the financial condition of its customers, historical trends, and the time outstanding of specific balances to estimate the amount of accounts receivable that may not be collected in the future and records the appropriate provision. Inventories – Inventories are stated at the lower of cost or net realizable value, determined on the first-in, first-out ("FIFO") basis. The value of inventory may decline as a result of surplus inventory, price reductions, or technological obsolescence. It is the Company’s policy to carry reserves against the carrying value of inventory when items have no future demand (obsolete inventory) and additionally, where inventory items on hand have demand, yet have insufficient forecasted activity to consume the entire stock within a reasonable period. It is the Company’s policy to carry reserves against the carrying value of such at-risk inventory items after considering the nature of the risk and any mitigating factors. Prepaid and Other Current Assets – Prepaid and other current assets at December 31, 2017 includes $10.0 million held in escrow that will be received nine months from the completion of the sale of the Timing Device Business. The remaining balance at December 31, 2017 and 2016 is made up of prepaid insurance, supplier prepayments, prepaid licensing fees, and other miscellaneous prepaid assets, none of which are individually significant. Property, Plant, and Equipment - Property, plant, and equipment includes the historic cost of land, buildings, equipment, and significant improvements to existing plant and equipment or, in the case of acquisitions, a fair market value appraisal of such assets completed at the time of acquisition. Property, plant, and equipment also includes the cost of purchased software. Expenditures for maintenance, repairs, and minor renewals are expensed as incurred. When property or equipment is sold or otherwise disposed of, the related cost and accumulated depreciation is removed from the respective accounts, and the gain or loss realized on disposition is reflected in earnings. The Company historically depreciates its assets on a straight-line basis over their estimated useful lives as follows: buildings and improvements 5 to 31.5 years; machinery and equipment 1.5 to 7 years; furniture and fixtures 3 to 7 years; vehicles 3 years; and software 3 to 7 years. Derivative Instruments - The Company uses derivative financial instruments to hedge its exposures to various risks, including interest rate and foreign currency exchange rate risk. The Company does not enter into derivative financial instruments for speculative purposes and does not have a material portfolio of derivative financial instruments. Derivative financial instruments used for hedging purposes must be designated and effective as a hedge of the identified risk exposure at inception of the contract. The Company recognizes all derivatives as either assets or liabilities on the Consolidated Balance Sheet and measures those instruments at fair value. For derivatives designated as hedges of the fair value of assets or liabilities, the changes in fair value of both the derivatives and of the hedged items are recorded in current earnings. For derivatives designated as cash flow hedges, the effective portion of changes in the fair value of the derivatives is recorded as a component of other comprehensive earnings and subsequently recognized in net earnings when the hedged items impact earnings. Goodwill and Indefinite-Lived Intangible Assets - Goodwill represents the excess of purchase consideration over the fair value of the net assets of businesses acquired. Goodwill and certain other intangible assets deemed to have indefinite lives (primarily trademarks) are not amortized. Instead, goodwill and indefinite-lived intangible assets are tested for impairment at least annually, or more frequently if indicators of impairment exist. The Company conducts its annual impairment evaluation in the fourth quarter of each year on October 1. Recoverability of goodwill is measured at the reporting unit level. The Company identified four reporting units for its annual goodwill impairment test. Following the sale of the Timing Device Business on November 28, 2017, the Company has three reporting units. The test compares the fair value of each reporting unit using a discounted cash flow method to its carrying value. Impairment is measured as the amount by which the carrying value of a reporting unit exceeds its fair value. This method uses the Company’s market participant assumptions including projections of future cash flows, determinations of appropriate discount rates, and other assumptions which are considered reasonable and inherent in the discounted cash flow analysis. The projections are based on historical performance and future estimated results. These assumptions require significant judgment and actual results may differ from estimated amounts. The fair value of all of the Company’s reporting units exceeded the carrying values by at least 40% , resulting in no goodwill impairment charges. Potential circumstances that could have a negative effect on the fair value of our reporting units include, but are not limited to, lower than forecasted growth rates or profit margins and changes in the weighted average cost of capital. A reduction in the estimated fair value of the reporting units could trigger an impairment in the future. The Company cannot predict the occurrence of certain events or changes in circumstances that might adversely affect the carrying value of goodwill and intangible assets. In testing its other indefinite-lived intangible assets for impairment, the Company uses a relief from royalty method to calculate and compare the fair value of the intangible asset to its carrying value. This method estimates the fair value of trademarks by calculating the present value of royalty income that could hypothetically be earned by licensing the trademark to a third party over the remaining useful life. Any excess of carrying value over the estimated fair value is recognized as an impairment loss. No impairment of indefinite-lived intangibles was indicated for the years ended December 31, 2017 , 2016 , or 2015 . See Note 7. Goodwill and Other Intangible Assets for additional information on goodwill and indefinite-lived intangible assets. Other Intangible and Long-Lived Assets - Other intangible assets with determinable lives consist primarily of customer relationships, unpatented technology, patents, and trademarks and are amortized over their estimated useful lives, historically ranging from 5 to 15 years. The Company relies on patents and proprietary technology, and seeks patent protection for products and production methods. The Company capitalizes external legal costs incurred in the defense of its patents when it believes that a significant, discernible increase in value will result from the defense and a successful outcome of the legal action is probable. These costs are amortized over the remaining estimated useful life of the patent, which is typically 7 to 10 years. The Company’s assessment of future economic benefit and/or the successful outcome of legal action related to patent defense, which involves considerable management judgment and a different outcome could result in material write-offs of the carrying value of these assets. During the years ended December 31, 2017 and 2016 , the Company capitalized no legal costs related to the defense of its patents. For the year ending December 31, 2015 , the Company capitalized $0.5 million in legal costs related to the defense of its patents. Long-lived assets (including intangible assets with determinable lives) are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If an indicator of impairment exists for any grouping of assets, an estimate of undiscounted future cash flows is produced and compared to its carrying value. If an asset is determined to be impaired, the loss is measured by the excess of the carrying amount of the asset over its fair value as determined by an estimate of discounted future cash flows. During 2015, Knowles recorded a pre-tax impairment charge of $191.5 million resulting from the carrying value of the Speaker and Receiver Product Line’s net assets being greater than the fair market value. In addition, Knowles identified other asset impairments related to the Speaker and Receiver Product Line of $4.1 million during the year ended December 31, 2015. See Note 2. Disposed and Discontinued Operations for additional details. During the years ended December 31, 2017 , 2016 , and 2015 , the Company recorded impairments and other charges related to its continuing operations of $ 21.3 million , $0.5 million , and $5.6 million , respectively. See Note 4. Impairments for additional details. Foreign Currency - Assets and liabilities of non-U.S. subsidiaries, where the functional currency is not the U.S. dollar, are translated into U.S. dollars at year-end exchange rates. Revenue and expense items are translated using weighted-average yearly exchange rates. Foreign currency translation gains and losses are included as a component of Accumulated other comprehensive loss. Assets and liabilities of an entity that are denominated in currencies other than an entity’s functional currency are re-measured into the functional currency using end of period exchange rates or historical rates where applicable to certain balances. Gains and losses related to these re-measurements are recorded within the Consolidated Statements of Earnings as a component of Other expense (income), net. Revenue Recognition - Revenue is recognized when all of the following conditions are satisfied: a) persuasive evidence of an arrangement exists, b) price is fixed or determinable, c) collectability is reasonably assured, and d) delivery has occurred or services have been rendered. The majority of the Company’s revenue is generated through the manufacture and sale of a broad range of specialized products and components, with revenue recognized upon transfer of title and risk of loss. The Company recognizes third-party licensing or royalty income as revenue over the related contract term when collection is reasonably assured. The Company does not have significant service revenue or multiple deliverable arrangements. Revenue is recognized net of customer discounts, rebates, and returns. Rebates are recognized over the contract period based on expected revenue levels. Sales discounts and rebates totaled $9.1 million , $8.7 million , and $9.0 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Returns and allowances totaled $8.5 million , $5.1 million , and $6.7 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Stock-Based Compensation – The principal awards issued under the stock-based compensation plans include stock options, restricted stock units ("RSUs"), and performance share units ("PSUs"). The cost for such awards is measured at the grant date based on the fair value of the award. The value of the portion of the award that is expected to ultimately vest is generally recognized as expense on a straight-line basis, generally over the explicit service period and is included in Cost of goods sold, Research and development expenses, and Selling and administrative expenses in the Consolidated Statements of Earnings, depending on the functional area of the underlying employees. The Company uses the Black-Scholes valuation model to estimate the fair value of stock options granted to employees. The fair value of each RSU granted is equal to the share price at the date of the grant. The fair value of each PSU is determined using a binomial model simulation. At the time of grant, the Company estimates forfeitures, based on historical experience, in order to estimate the portion of the award that will ultimately vest. See Note 13. Equity Incentive Program for additional information related to the Company’s stock-based compensation. Income Taxes - The Company records a provision for income taxes for the anticipated tax consequences of the reported results of operations using the asset and liability method. Under this method, the Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. The Company offsets and presents deferred tax liabilities and assets, as well as any related valuation allowance, as a single non-current amount on the Consolidated Balance Sheets on a jurisdictional basis. The Company establishes valuation allowances for its deferred tax assets if, based on all available positive and negative evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. In making such assessments, significant weight is given to evidence that can be objectively verified. The assessment of the need for a valuation allowance requires considerable judgment on the part of management with respect to the benefits that could be realized from future taxable income, as well as other positive and negative factors. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income, and tax-planning strategies in making this assessment. The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Adjustments are made to these reserves when facts and circumstances change, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on the Company's financial condition and operating results. The provision for income taxes includes the effects of any reserves that are believed to be appropriate, as well as the related net interest and penalties. On December 22, 2017, the U.S. bill commonly referred to as the Tax Cuts and Jobs Act (“Tax Reform Act”) was enacted, which significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system, and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. The Tax Reform Act also provided for a one-time deemed repatriation of post-1986 undistributed foreign subsidiary earnings and profits (“E&P”) through the year ended December 31, 2017. The Global Intangible Low-Taxed Income ("GILTI") provisions of the Tax Reform Act require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company expects that it will be subject to incremental U.S. tax on GILTI income beginning in 2018, due to expense allocations required by the U.S. foreign tax credit rules. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its Consolidated Financial Statements for the year ended December 31, 2017. On December 22, 2017, the Securities and Exchange Commission ("SEC") staff issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. The Company has recognized the provisional tax impacts related to deemed repatriated earnings, the change in the beginning of year valuation allowance, and the benefit for the remeasurement of deferred tax assets and liabilities, and included these amounts in its Consolidated Financial Statements for the year ended December 31, 2017. The final impact may differ from these provisional amounts, possibly materially, due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of the Tax Reform Act. In accordance with SAB 118 the financial reporting impact of the Tax Reform Act will be completed in the fourth quarter of 2018. Research and Development Costs – Research and development costs, including qualifying engineering costs, are expensed when incurred. Non-cash Investing Activities - Purchases of property, plant, and equipment included in accounts payable at December 31, 2017 , 2016 , and 2015 were $8.5 million , $1.5 million , and $2.1 million , respectively. The Company also entered into a capital lease for new equipment in 2015 with a corresponding capital lease obligation of $13.6 million at December 31, 2015. These non-cash amounts are not reflected as outflows to Additions to property, plant, and equipment within investing activities of the Consolidated Statements of Cash Flows for the respective periods. Reclassifications - Certain amounts in prior years have been reclassified to conform to the current year presentation. Refer to the Recently Issued Accounting Standards section below. Recently Issued Accounting Standards In August 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2017-12 with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements and simplify the application of hedge accounting guidance. The standard is effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The standard requires adoption on a modified retrospective basis for hedging relationships existing as of the adoption date and on a prospective basis for the amended presentation and disclosure requirements. Early adoption is permitted. The Company has not yet determined the effect of the standard on its ongoing financial reporting and plans to adopt this standard on January 1, 2019. In May 2017, the FASB issued ASU 2017-09 that provides guidance about when a change to the terms or conditions of a share-based payment award must be accounted for as a modification. The new guidance requires modification accounting if the fair value, vesting condition, or the classification of the award is not the same immediately before and after a change to the terms and conditions of the award. This standard is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The standard requires adoption on a prospective basis for awards modified on or after the adoption date. The standard will not have a significant impact upon adoption on January 1, 2018. In March 2017, the FASB issued ASU 2017-07 primarily to improve the presentation of net periodic pension and post-retirement benefit cost. The new guidance requires that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the statement of earnings separately from the service cost component and outside of any subtotal of operating income. This standard is effective for public business entities for annual periods or any interim periods beginning after December 15, 2017. The standard requires adoption on a retrospective basis for the presentation of net benefit cost components. The standard will not have a significant impact upon adoption on January 1, 2018. In January 2017, the FASB issued ASU 2017-01, which requires a reporting entity to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or liabilities. This standard is effective for public business entities for annual periods beginning after December 15, 2017, including interim periods within those periods. Early adoption is permitted under specific circumstances and prospective application of the guidance is required. The standard will not have a significant impact upon adoption on January 1, 2018. In August 2016, the FASB issued ASU 2016-15 with the objective of reducing the existing diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The new guidance requires evaluation of cash receipts and payments on the basis of the nature of the underlying cash flows and provides clarity for categorization for specific transactions. This standard is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The standard requires adoption on a retrospective basis. The standard will not have a significant impact upon adoption on January 1, 2018. In February 2016, the FASB issued ASU 2016-02, which requires a lessee to recognize a lease liability and asset for all leases, including operating leases, with a term greater than 12 months on its balance sheet. The standard requires a modified retrospective transition method for all entities. This ASU also provides clarification surrounding the presentation of the effects of the leases in the statement of earnings and statement of cash flows. This standard is effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company has not yet determined the effect of the standard on its ongoing financial reporting and plans to adopt this standard on January 1, 2019. In January 2016, the FASB issued ASU 2016-01, which requires a company to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk if the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This standard is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The standard requires adoption on a modified retrospective basis. The standard will not have a significant impact upon adoption on January 1, 2018. In May 2014, the FASB issued ASU 2014-09 and issued subsequent amendments to the initial guidance in August 2015, March 2016, April 2016, May 2016, and December 2016 within ASU 2015-14, ASU 2016-08, ASU 2016-10, ASU 2016-12, and ASU 2016-20, respectively. The core principal of the guidance is to provide a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. The guidance also requires additional disclosure about the nature, amount, timing, and uncertainty of revenue and cash flows arising from customer contracts. The standard is effective for annual and interim periods beginning after December 15, 2017, which will require the Company to adopt these provisions in the first quarter of fiscal year 2018. This update permits the use of either the retrospective or modified retrospective (cumulative effect) transition method. ASU 2016-12, issued in May 2016, removes the requirement to disclose the effect of the accounting change in the period of adoption, but still requires the Company to disclose the effect of the changes on any prior periods retrospectively adjusted. The status of the Company’s implementation process is summarized below: • The Company employed a cross-functional approach in assessing the potential impacts of the standard. • The Company determined the key factors from the five-step model for recognizing revenue under the new standard that may be applicable to the business units that comprise the Company’s reportable segments. • Review of the Company’s contract portfolio, which focused on contracts with significant customers, was completed prior to the filing date of this Annual Report on Form 10-K as of December 31, 2017. • Evaluations of contract provisions and a comparison of historical accounting policies to the requirements of the new standard are complete. The Company expects the impact of the adoption to be immaterial to net earnings on an ongoing basis as the analysis of contracts under the new standard supports the recognition of revenue at a point in time, resulting in revenue recognition timing that is materially consistent with our historical practice of recognizing revenue when title and risk of loss pass to the customer. • Although the standard is expected to have an immaterial impact to net earnings on an ongoing basis, the Company is implementing changes to its business processes and controls to support recognition and disclosure under the new guidance, including ongoing contract review requirements. • The Company will elect to account for shipping and handling activities that occur after control of the related good transfers as fulfillment activities rather than evaluating such activities as performance obligations. The Company will adopt this new guidance on January 1, 2018 using the modified retrospective method. The Company does not expect to recognize a cumulative effect adjustment to retained earnings as of the date of adoption based on the immaterial impact described above. Recently Adopted Accounting Standards In January 2017, the FASB issued ASU 2017-04, which simplifies an entity's measurement of goodwill for impairment testing purposes by eliminating the requirement to perform a hypothetical purchase price allocation. A goodwill impairment charge will now be recognized for the amount by which the carrying value of a reporting unit exceeds its fair value, not to exceed the carrying amount of goodwill. This standard is effective for public business entities for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company adopted this guidance prospectively on January 1, 2017. The Company's adoption of this standard did not have an impact on the Consol

Disposed and Discontinued Opera

Disposed and Discontinued Operations (Notes)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure	Management and the Board of Directors periodically conduct strategic reviews of the Company's businesses. On November 28, 2017, the Company completed the sale of the Timing Device Business, part of the Precision Devices segment, to Microsemi Corporation for $130.0 million , plus purchase price adjustments for a net amount of $133.3 million . The Company recorded a gain of $62.3 million as a result of the sale, which included $0.4 million of gain amounts reclassified from Accumulated other comprehensive loss into earnings related to currency translation adjustments. The purchase price includes $10.0 million held in escrow that will be received nine months from the completion of the sale and is recorded in the Prepaid and other current assets line on the Consolidated Balance Sheet. On July 7, 2016, the Company completed the sale of its Speaker and Receiver Product Line for $45.0 million in cash, less purchase price adjustments for a net amount received of $40.6 million . The Company recorded a loss of $25.6 million as a result of the sale, which included $26.9 million of loss amounts reclassified from Accumulated other comprehensive loss into earnings related to currency translation adjustments. The results of operations and financial positions of the Timing Device Business and Speaker and Receiver Product Line have been reclassified to discontinued operations for all periods presented as these disposals represent strategic shifts that have a major effect on the Company's results of operations. Summarized results of the Company's discontinued operations are as follows: Years Ended December 31, (in millions) 2017 2016 2015 Revenues $ 92.2 $ 156.4 $ 331.0 Cost of goods sold 61.5 136.1 319.3 Impairment charges (1) 0.4 0.4 50.1 Restructuring charges - cost of goods sold 0.1 8.9 0.9 Gross profit (loss) 30.2 11.0 (39.3 ) Research and development expenses (1) 7.7 15.1 25.7 Selling and administrative expenses 18.5 26.9 58.3 Impairment charges (1) — — 143.3 Restructuring charges 0.2 3.4 3.5 Operating expenses 26.4 45.4 230.8 Other expense (income), net 1.3 (0.9 ) (0.6 ) (Gain) loss on sale of business (62.3 ) 25.6 — Earnings (loss) from discontinued operations before taxes (2) 64.8 (59.1 ) (269.5 ) Provision for (benefit from) income taxes 3.0 3.0 (18.3 ) Earnings (loss) from discontinued operations, net of tax $ 61.8 $ (62.1 ) $ (251.2 ) (1) The Company evaluates long-lived assets for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. During the fourth quarter of 2015, it was determined that the Speaker and Receiver Product Line lacked a future path to profitability, which included a thorough evaluation of key assumptions including selling prices, product margins, as well as future product demand and suggested that the carrying value of the product line’s assets may be impaired. Through the utilization of undiscounted future cash flows to determine the fair value of the assets, the Company concluded that the fair values of the intangible assets and fixed assets associated with the Speaker and Receiver Product Line were less than their respective carrying values at December 31, 2015. As a result, the Speaker and Receiver Product Line's intangible assets and fixed assets were written down to their fair values and Knowles incurred pre-tax impairment charges of $143.3 million and $48.2 million , respectively. In addition, during the year ended December 31, 2015, Knowles incurred other pre-tax impairment charges of $4.1 million . These impairments were recorded within the discontinued operations line items as follows: $50.1 million in Impairment charges within Gross profit (loss), $2.2 million in Research and development expenses, and $143.3 million in Impairment charges within Operating expenses. (2) The Company's policy is to not allocate interest expense to discontinued operations unless it is directly attributable to the operations. The results of operations of the Timing Device Business and Speaker and Receiver Product Line did not have any such interest expense in the periods presented. Assets and liabilities of discontinued operations are summarized below: (in millions) December 31, 2017 December 31, 2016 Assets of discontinued operations: Cash and cash equivalents $ — $ 2.8 Receivables, net of allowances of nil and $0.4, respectively 1.2 19.2 Inventories, net — 17.4 Prepaid and other current assets 0.5 0.6 Total current assets 1.7 40.0 Property, plant, and equipment, net — 13.3 Goodwill — 23.0 Intangible assets, net — 3.7 Other assets and deferred charges — 0.1 Total assets (1) $ 1.7 $ 80.1 Liabilities of discontinued operations: Accounts payable $ 0.1 $ 9.1 Other current liabilities 5.5 13.6 Total current liabilities 5.6 22.7 Deferred income taxes — 0.1 Other liabilities — 0.9 Total liabilities (1) $ 5.6 $ 23.7 (1) In connection with the sale of the Timing Device Business, the Company retained certain obligations related to employees of the Timing Device Business. This arrangement results in maintaining asset and liability balances, which are expected to be settled in the next 12 months. The following table presents the depreciation, amortization, and capital expenditures related to discontinued operations: Years Ended December 31, (in millions) 2017 2016 2015 Depreciation $ 2.3 $ 3.3 $ 39.4 Amortization of intangible assets $ 1.2 $ 1.4 $ 23.9 Capital expenditures $ 2.1 $ 6.5 $ 26.3 There were no capital expenditures in accounts payable at December 31, 2017 . Capital expenditures included in accounts payable at December 31, 2016 and 2015 were $0.1 million and $1.6 million , respectively.

Acquisition Acquisition

Acquisition Acquisition	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisition	On January 11, 2017, the Company completed an acquisition of certain assets of a capacitors manufacturer for cash consideration of $3.7 million , of which $2.5 million was paid during 2017, with the remaining $1.2 million to be paid in installments from 2018 through the first quarter of 2019. The acquisition's operations are included in the PD segment. The financial results of this acquisition were included in our Consolidated Financial Statements beginning January 11, 2017. On July 1, 2015, the Company completed its acquisition of all of the outstanding shares of common stock of Audience, Inc. ("Audience") for a consideration per Share of $2.51 in cash and 0.13207 shares of Knowles common stock pursuant to the Agreement and Plan of Merger dated April 29, 2015. The financial results of Audience were included in our Consolidated Financial Statements beginning July 1, 2015. As a result of the acquisition, the Company issued 3.2 million shares and paid $61.6 million in cash to former holders of Shares and for the conversion of vested in-the-money Audience stock options. The Company also converted unvested in-the-money Audience stock options and RSUs for an aggregate of 461,371 shares of its common stock. The fair value of unvested equity awards relating to future services, and not yet earned, are recorded as operating expenses over the remaining service periods. Total consideration was approximately $92.8 million , net of cash and short-term investments acquired of $30.5 million . The revenues and net losses from Audience operations in the six months ending December 31, 2015 were $19.0 million and $31.6 million , respectively. The total purchase consideration of approximately $123.3 million consists of the following: (in millions, except per share amounts) Cash consideration paid to Audience shareholders and equity award holders $ 61.6 Fair value of shares of Knowles common stock issued to Audience shareholders and equity award holders 60.2 Fair value of RSUs assumed 1.5 Fair value of total consideration $ 123.3 Impact of Audience Acquisition and Pro-forma Summary The following unaudited pro-forma summary presents consolidated financial information as if Audience had been acquired on January 1, 2014. The unaudited pro-forma financial information is based on historical results of operations and financial position of the Company and Audience. The pro-forma results include: • estimated amortization of a definite-lived developed technology intangible asset, • the estimated cost of the inventory step-up to fair value, • the estimated depreciation expense of the fixed asset step-up to fair value, • interest expense associated with debt that would have been incurred in connection with the acquisition, and • the reclassification of Audience transaction costs from 2015 to the first quarter of 2014. The unaudited pro-forma financial information does not necessarily represent the results that would have occurred had the acquisition occurred on January 1, 2014. In addition, the unaudited pro-forma information should not be deemed to be indicative of future results. Year Ended December 31, (in millions, except share and per share amounts) 2015 Revenues from continuing operations: As reported $ 753.6 Pro-forma 783.6 Earnings (loss) from continuing operations: As reported $ 17.4 Pro-forma (36.5 ) Basic earnings (loss) per share from continuing operations: As reported $ 0.20 Pro-forma (0.41 ) Diluted earnings (loss) per share from continuing operations: As reported $ 0.20 Pro-forma (0.41 )

Impairments

Impairments	12 Months Ended
	Dec. 31, 2017
Asset Impairment Charges [Abstract]
Impairments	4. Impairments The Company evaluates long-lived assets for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. During the second quarter of 2017, an updated strategic plan was completed for Audio segment product lines. The updated strategic plan identified a decline of future demand for a specific product line, which indicated projected future cash flows may not be sufficient to recover the carrying value of the associated unpatented technologies and property, plant, and equipment assets. The utilization of undiscounted future cash flows was used to determine recoverability of the long-lived assets. The fair value of the intangibles was determined through the use of discounted cash flows, and the fair value of fixed assets was determined using their liquidation value. As a result of this analysis, the Company concluded that the fair values of these long-lived assets were less than their respective carrying values. The Company recorded total impairment charges of $21.3 million , of which $5.1 million was related to fixed assets and $16.2 million was related to intangible assets. The Company recorded $1.4 million of the charges within Impairment charges in Gross profit and recorded $19.9 million within the Impairment charges line item in Operating expenses within the Consolidated Statements of Earnings. During the year ended December 31, 2016 , the Company identified asset impairments within the Audio segment of $0.5 million , which are primarily related to restructuring actions to focus research and development efforts on the design of new products in our core business. The Company recorded $0.3 million within Impairment charges in Gross profit and $0.2 million within the Impairment charges line item in Operating expenses within the Consolidated Statements of Earnings. During the year ended December 31, 2015 , the Company identified asset impairments within the Audio and PD segments of $3.5 million and $2.1 million , respectively. These impairments are a result of restructuring actions to consolidate its manufacturing footprint and other measures to further optimize operations. The Company recorded impairments of fixed and other assets of $3.3 million within Impairment charges in Gross profit within the Consolidated Statements of Earnings. The Company recorded impairments of intangible assets of $1.4 million and fixed and other assets of $0.9 million within the Impairment charges line item in Operating expenses within the Consolidated Statements of Earnings.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventory, Net [Abstract]
Inventories, net	5. Inventories, net The following table details the major components of inventories, net: (in millions) December 31, 2017 December 31, 2016 Raw materials $ 65.9 $ 51.1 Work in progress 21.3 13.3 Finished goods 60.8 51.0 Subtotal 148.0 115.4 Less reserves (22.4 ) (24.6 ) Total $ 125.6 $ 90.8

Property, Plant and Equipment,

Property, Plant and Equipment, net	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	6. Property, Plant, and Equipment, net The following table details the major components of property, plant, and equipment, net: (in millions) December 31, 2017 December 31, 2016 Land $ 7.7 $ 7.7 Buildings and improvements 103.2 93.7 Machinery, equipment, and other 441.1 382.5 Subtotal 552.0 483.9 Less accumulated depreciation (369.0 ) (311.0 ) Total $ 183.0 $ 172.9 Depreciation expense totaled $46.5 million , $50.8 million , and $54.2 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The Company recorded fixed and other asset impairments of $5.1 million , $0.5 million , and $4.2 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	12 Months Ended
	Dec. 31, 2017
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses and Other Liabilities	8. Other Accrued Expenses and Other Liabilities The following table details the major components of other accrued expenses: (in millions) December 31, 2017 December 31, 2016 Restructuring and exit costs $ 4.8 $ 2.6 Sales volume rebates 4.7 3.2 Accrued short-term capital leases 2.5 2.4 Accrued taxes other than income taxes 2.4 2.1 Warranty 2.1 1.0 Accrued insurance 1.9 1.6 Hedging liability — 3.6 Other (1) 9.8 5.9 Total $ 28.2 $ 22.4 (1) Represents accrued commissions (non-employee) and other miscellaneous accruals, none of which are individually significant. The following table details the major components of other liabilities: (in millions) December 31, 2017 December 31, 2016 Transition tax liability (1) 25.9 — Deferred compensation, including defined benefit plans 18.7 18.7 Long-term capital leases 12.3 13.2 Unrecognized tax benefits 6.5 4.9 Restructuring and exit costs 0.3 0.2 Other 4.2 3.6 Total $ 67.9 $ 40.6 (1) See Note 12. Income Taxes for additional information on this liability. Warranty Accruals Estimated warranty program claims are provided for at the time of sale. Amounts provided for are based on historical costs and adjusted for new claims. The changes in the carrying amount of product warranties were as follows: Years Ended December 31, (in millions) 2017 2016 Beginning balance, January 1 $ 1.0 $ 1.0 Provision for warranties 2.8 2.5 Settlements made (1.3 ) (2.1 ) Other adjustments, including currency translation (0.4 ) (0.4 ) Ending balance, December 31 $ 2.1 $ 1.0

Hedging Transactions and Deriva

Hedging Transactions and Derivative Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Hedging Transactions and Derivative Instruments	10. Hedging Transactions and Derivative Instruments The Company is affected by changes in certain market conditions. These changes in market conditions may adversely impact the Company’s financial performance and are referred to as "market risks." The Company uses derivatives as a risk management tool to mitigate the potential impact of certain market risks, which are primarily foreign currency risk and interest rate risk related to ongoing business operations. Cash Flow Hedging The Company uses cash flow hedges to minimize the variability in cash flows of assets, liabilities, or forecasted transactions caused by fluctuations in foreign currency exchange rates or market interest rates. These derivatives, which are designated cash flow hedges, are carried at fair value. The changes in their fair values are recorded to Accumulated Other Comprehensive Income (Loss) ("AOCI") and reclassified in current earnings when the hedge contract matures or becomes ineffective. To manage its exposure to foreign currency exchange rates, the Company has entered into currency deliverable forward contracts. These derivative instruments allow the Company to hedge portions of its forecasted sales and purchases, which are expected to occur within the next twelve months and are denominated in non-functional currencies. The Company maintains a foreign currency cash flow hedging program to primarily reduce the risk that the net U.S. dollar cash inflows from non-U.S. dollar sales and non-U.S. dollar net cash outflows from procurement activities will be adversely affected by changes in foreign currency exchange rates. At December 31, 2017 and 2016 , the notional value of the derivatives related to currency forward contracts, principally the Chinese yuan, Malaysian ringgit, and Philippine peso, was $17.9 million and $75.4 million , respectively. To manage its exposure to market risk for changes in interest rates, the Company entered into an interest rate swap on November 12, 2014 to convert variable interest rate payments into a fixed rate on a notional amount of $100.0 million of debt for monthly interest payments that began in January 2016 and ends in July 2018. In December 2017, the Company entered into a partial termination of the interest rate swap and reduced the notional amount to $50.0 million . The Company designated the swap as a cash flow hedge with re-measurement gains and losses recorded through AOCI. Economic (Non-Designated) Hedging In addition to derivative instruments that are designated and qualify for hedge accounting, the Company also uses certain derivatives as economic hedges of foreign currency risk. Although these derivatives were not designated and/or did not qualify for hedge accounting, they are effectively economic hedges. The changes in fair value of these economic hedges are immediately recognized in earnings. The Company uses foreign currency economic hedges to offset the earnings impact that fluctuations in foreign currency exchange rates have on certain monetary assets and liabilities denominated in non-functional currencies. The Company does not enter into these hedges for speculative reasons. These derivatives are carried at fair value with changes in the fair value recorded in Other expense (income), net. In addition, these derivative instruments minimize the impact of exchange rate movements on the Company’s balance sheet, as the gains or losses on these derivatives are intended to offset gains and losses from the reduction of the hedged assets and liabilities. At December 31, 2017 , the notional value of the derivatives related to economic hedging was $6.4 million . The Company held no open positions related to economic hedges at December 31, 2016 . The notional amounts of the derivative financial instruments do not necessarily represent amounts exchanged by the parties and, therefore, are not a direct measure of our exposure to the financial risks described above. The amounts exchanged are calculated by reference to the notional amounts and by other terms of the derivatives, such as interest rates, foreign currency exchange rates, or other financial indices. The Company does not view the fair values of its derivatives in isolation, but rather in relation to the fair values or cash flows of the underlying hedged transactions or other exposures. Virtually all of our derivatives are straightforward over-the-counter instruments with liquid markets. Fair Value Measurements All derivatives are carried at fair value on the Company’s Consolidated Balance Sheets. ASC 820, Fair Value Measurement, establishes a fair value hierarchy that requires the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the hierarchy is based on the lowest level of input that is significant to the fair value measurement. ASC 820 establishes three levels of inputs that may be used to measure fair value as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 - Observable inputs other than quoted prices included in Level 1, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities. Level 3 - Unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions. The Company determines the fair values of its derivatives based on standard valuation models or observable market inputs such as quoted market prices, foreign currency exchange rates, or interest rates; therefore, the Company classifies the derivatives within Level 2 of the valuation hierarchy. The following table sets forth the fair values of derivative instruments held by the Company as of December 31, 2017 and 2016 and the balance sheet lines to which they are recorded: (in millions) Hedge Type Balance Sheet Line Item December 31, 2017 December 31, 2016 Cash flow hedges Prepaid and other current assets $ 0.6 $ — Cash flow hedges Other accrued expenses — 3.6 Cash flow hedges Other liabilities — 0.2 Accounting for derivatives requires that derivative instruments be recognized as either assets or liabilities at fair value. However, accounting for the gains and losses resulting from changes in fair value depends upon the use of the derivative and whether it is considered designated and qualified for hedge accounting. For non-designated foreign currency economic hedge derivative contracts, for which the Company does not apply hedge accounting, the changes in fair value of the derivative instrument are immediately recognized in earnings within Other expense (income), net. For currency forward contracts and interest rate swaps, which are designated as cash flow hedge derivatives and for which the Company applies hedge accounting guidance, the fair value of the effective portion of these hedges is recorded within AOCI and reclassified and recognized in current earnings when the hedge contract matures or is determined to be ineffective. As a result, the Company has recorded a $0.5 million gain and a $3.2 million loss to AOCI on the Company’s Consolidated Balance Sheets as of December 31, 2017 and 2016 , respectively. For economic hedges, for which the Company does not apply hedge accounting, the following (gains) losses were recorded for the years ended December 31, 2017 , 2016 , and 2015 : (in millions) Years Ended December 31, Hedge Type Statement of Earnings Line 2017 2016 2015 Economic Hedges Other expense (income), net $ (0.3 ) $ 2.0 $ 0.3 The following table presents the pre-tax impact of changes in the fair values of the designated derivatives, which qualify for hedge accounting during the years ended December 31, 2017 , 2016 , and 2015 . Knowles reclassified these losses out of AOCI into Other expense (income), net as follows: (in millions) Years Ended December 31, Hedge Type Statement of Earnings Line 2017 2016 2015 Cash flow hedges Other expense (income), net $ 0.5 $ 1.0 $ —

Borrowings and Lines of Credit

Borrowings and Lines of Credit	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowings and Lines of Credit	11. Borrowings Borrowings (net of debt issuance costs, debt discount, and amortization) consist of the following: (in millions) December 31, 2017 December 31, 2016 3.25% Convertible Senior Notes $ 141.9 $ 135.1 Term loan and revolving credit facility 50.7 163.1 Total 192.6 298.2 Less current maturities — 9.7 Total long-term debt $ 192.6 $ 288.5 Total debt principal payments over the next five years are as follows: (in millions) 2018 2019 2020 2021 2022 Debt principal payments (1) $ — $ — $ — $ 172.5 $ 50.7 (1) There are no required principal payments due under the 3.25% Convertible Senior Notes or the revolving credit facility until maturities in November 2021 and October 2022, respectively. 3.25% Convertible Senior Notes Due November 1, 2021 In May 2016, the Company issued $172.5 million aggregate principal amount of 3.25% convertible senior notes due November 1, 2021 ("the Notes"), unless earlier repurchased by the Company or converted pursuant to their terms. Interest is payable semiannually in arrears on May 1 and November 1 of each year and commenced on November 1, 2016. The Notes are governed by an Indenture (the "Indenture") between the Company, as issuer, and U.S. Bank National Association as trustee. Upon conversion, the Company will pay or deliver cash, shares of the Company's common stock, or a combination of cash and shares of common stock, at the Company's election. The initial conversion rate is 54.2741 shares of common stock per $1,000 principal amount of Notes. The initial conversion price is $18.4250 per share of common stock. The conversion rate will be subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change (as defined in the Indenture), the Company may be required, in certain circumstances, to increase the conversion rate by a number of additional shares for a holder that elects to convert its Notes in connection with such make-whole fundamental change. Prior to the close of business on the business day immediately preceding August 1, 2021, the Notes will be convertible only under the following circumstances: = during any calendar quarter and only during such calendar quarters, if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; = during the five business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of Notes was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or = upon the occurrence of specified corporate events. On or after August 1, 2021 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their Notes, in multiples of $1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. A s of December 31, 2017 , no event has occurred that would permit the conversion of the Notes. The Notes are the Company’s senior unsecured obligations. In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the face value of the Notes as a whole. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the term of the Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the transaction costs related to the Notes issuance, the Company allocated the total amount incurred to the liability and equity components based on their relative values. Issuance costs attributable to the liability component, totaling $5.0 million , are being amortized to interest expense over the term of the Notes, and issuance costs attributable to the equity component, totaling $1.3 million , were netted with the equity component in stockholders' equity. Additionally, the Company recorded a deferred tax asset of $0.5 million on a portion of the equity component transaction costs which are deductible for tax purposes and immediately recorded a valuation allowance against this deferred tax asset. The Notes consist of the following: (in millions) December 31, 2017 December 31, 2016 Liability component: Principal $ 172.5 $ 172.5 Less debt issuance costs and debt discount, net of amortization (30.6 ) (37.4 ) Total 141.9 135.1 Less current maturities — (0.9 ) Long-term portion $ 141.9 $ 136.0 Equity component (1) $ 29.9 $ 29.9 (1) Recorded in the Consolidated Balance Sheets within additional paid-in capital, inclusive of the $1.3 million of issuance costs in equity. The total estimated fair value of the Notes at December 31, 2017 was $191.4 million . The fair value was determined based on the closing trading price of the Notes as of the last trading day of 2017 . The following table sets forth total interest expense recognized related to the Notes: Years Ended December 31, (in millions) 2017 2016 3.25% coupon $ 5.6 $ 3.7 Amortization of debt issuance costs 0.9 0.6 Amortization of debt discount 5.8 3.6 Total $ 12.3 $ 7.9 Note Hedges To minimize the impact of potential economic dilution upon conversion of the Notes, the Company entered into convertible note hedge transactions (the “Note Hedges”) with respect to its common stock. In the second quarter of 2016, the Company paid an aggregate amount of $44.5 million for the Note Hedges. The Note Hedges will expire upon maturity of the Notes. The Note Hedges are intended to offset the potential dilution upon conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount upon conversion of the Notes in the event that the market value per share of the Company's common stock, as measured under the Note Hedges, is greater than the strike price of the Note Hedges. which initially corresponds to the initial conversion price of the Notes and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of the Notes. The Note Hedges are separate transactions entered into by the Company, and are not part of the Notes or the Warrants, and have been accounted for as part of additional paid-in capital. Holders of the Notes do not have any rights with respect to the Note Hedges. Warrants In addition to the Note Hedges, in the second quarter of 2016, the Company entered into warrant transactions, whereby the Company sold warrants to acquire shares of the Company's common stock at a strike price of $21.1050 per share (the “Warrants”). The Company received aggregate proceeds of $39.1 million from the sale of the Warrants. If the market price per share of the Company's common stock for the reporting period, as measured under the Warrants, exceeds the strike price of the Warrants, the Warrants could have a dilutive effect on the Company's common stock, unless the Company elects, subject to certain conditions, to settle the Warrants in cash. The Warrants are separate transactions entered into by the Company, and are not part of the Notes or the Note Hedges, and have been accounted for as part of additional paid-in capital. Holders of the Notes and Note Hedges do not have any rights with respect to the Warrants. Term Loan and Revolving Credit Facility Term loan and revolving credit facility borrowings consist of the following: (in millions) December 31, 2017 December 31, 2016 Term loan due January 2019 $ — $ 118.5 $300.0 million revolving credit facility due January 2019 — 45.0 $400.0 million revolving credit facility due October 2022 50.7 — Less debt issuance costs, net of amortization — (0.4 ) Total 50.7 163.1 Less current maturities — 10.6 Long-term portion $ 50.7 $ 152.5 On October 11, 2017, Knowles entered into a Revolving Credit Facility Agreement (the "New Credit Facility"). The New Credit Facility contains a five -year senior secured revolving credit facility providing for borrowings in an aggregate principal amount at any time outstanding not to exceed $400.0 million . Up to $100.0 million of the New Credit Facility will be available in Euro, Sterling, and other currencies requested by the Company and agreed to by each Lender and up to $50.0 million of the New Credit Facility will be made available in the form of letters of credit denominated in any currencies agreed by the issuing bank. The New Credit Facility serves as refinancing of indebtedness and terminates the Company's Amended and Restated Credit Agreement dated as of January 27, 2014, as amended and restated as of December 31, 2014 and supplemented from time to time (“Prior Credit Facilities”). At any time during the term of the New Credit Facility, the Company will be permitted to increase the commitments under the New Credit Facility or to establish one or more incremental term loan facilities under the New Credit Facility in an aggregate principal amount not to exceed $200.0 million for all such incremental facilities. Commitments under the New Credit Facility will terminate, and loans outstanding thereunder will mature, on October 11, 2022; provided, that if all the Company’s 3.25% Convertible Senior Notes Due November 1, 2021 have not been repaid, refinanced and/or converted to common stock of the Company by April 30, 2021, then the commitments under the New Credit Facility will terminate, and the loans outstanding thereunder will mature, on such earlier date. The interest rates under the New Credit Facility will be, at the Borrowers’ option (1) LIBOR (or, in the case of borrowings under the New Credit Facility denominated in Euro, EURIBOR) plus the rates per annum determined from time to time based on the total leverage ratio of the Company as of the end of and for the most recent period of four fiscal quarters for which financial statements have been delivered (the “Applicable Rate”); or (2) in the case of borrowings denominated in U.S. dollars, alternate base rate (“ABR”); provided, however, that any swingline borrowings shall bear interest at the rate applicable to ABR borrowings or, prior to the purchase of participations in such borrowings by the Lenders, at such other rate as shall be agreed between the Company and the swingline lender. The interest rate under the New Credit Facility is variable based on LIBOR at the time of the borrowing and the Company’s leverage as measured by a total indebtedness to Consolidated EBITDA ratio. Based upon the Company’s total indebtedness to Consolidated EBITDA ratio, the Company’s borrowing rate could range from LIBOR + 1.25% to LIBOR + 2.25% . In addition, a commitment fee accrues on the average daily unused portion of the New Credit Facility at a rate of 0.20% to 0.35% . The New Credit Facility includes requirements, to be tested quarterly, that the Company maintains (i) a minimum ratio of Consolidated EBITDA to consolidated interest expense of 3.25 to 1.0, (the "Interest Coverage Ratio"), (ii) a maximum ratio of Consolidated total indebtedness to Consolidated EBITDA of 3.75 to 1.0 ("the Leverage Ratio"), and (iii) a maximum ratio of senior secured indebtedness to Consolidated EBITDA of 3.25 to 1.0 (the "Senior Secured Leverage Ratio"). For these ratios, Consolidated EBITDA and consolidated interest expense are calculated using the most recent four consecutive fiscal quarters in a manner defined in the New Credit Facility. At December 31, 2017 , the Company was in compliance with these covenants and it expects to remain in compliance with all of its debt covenants over the next twelve months. On January 27, 2014, the Company entered into a $200.0 million five -year senior secured revolving credit facility as well as a $300.0 million five -year senior secured term loan facility pursuant to the Original Credit Agreement, which are referred to collectively as the "Prior Credit Facilities." On December 31, 2014, the Company amended its Prior Credit Facilities to (i) increase the amount of the revolving credit facility in the Original Credit Agreement to $350.0 million from $200.0 million , (ii) increase the amount of the letter of credit subfacility in the Original Credit Agreement to $50.0 million from $25.0 million , (iii) eliminate the swing line subfacility in the amount of up to $35.0 million in the Original Credit Agreement and (iv) reduce to $100.0 million from $250.0 million the amount of additional incremental revolving or term loans in the Original Credit Agreement. All other terms and conditions of the Prior Credit Facilities remained essentially the same. On February 9, 2016, the Company entered into a third amendment to its Prior Credit Facilities that includes a permanent reduction by the Company of the aggregate revolving commitment under the Prior Credit Facilities from $350.0 million to $300.0 million . On April 27, 2016, the Company entered into a fourth amendment to its Prior Credit Facilities to permit the Company to execute the offering of the Notes and the related transactions. The weighted-average interest rate on the Company's borrowings under the New Credit Facility and Prior Credit Facilities was 3.58% and 3.23% for the years ended December 31, 2017 and 2016 , respectively. The weighted-average interest rate on the Company's borrowings under the New Credit Facility and Prior Credit Facilities for the years ended December 31, 2017 and 2016 includes interest expense related to the monthly interest rate swap settlements. The weighted-average commitment fee on the revolving lines of credit was 0.36% and 0.39% for the years ended December 31, 2017 and 2016 , respectively. Interest expense and interest income for the years ended December 31, 2017 , 2016 , and 2015 were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Interest expense (1) $ 20.8 $ 20.5 $ 12.8 Interest income (0.2 ) (0.1 ) (0.1 ) Interest expense, net $ 20.6 $ 20.4 $ 12.7 (1) During 2017, the Company wrote off $0.4 million of debt issuance costs related to the Prior Credit Facilities to interest expense upon entering into the New Credit Facility. During 2016, the Company wrote off $0.7 million of debt issuance costs to interest expense in connection with the third amendment to its Prior Credit Facilities. See Note 10. Hedging Transactions and Derivative Instruments for information on derivatives used to manage interest rate risk.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes The components of earnings before income taxes and discontinued operations were: Years Ended December 31, (in millions) 2017 2016 2015 Domestic $ 402.7 $ (51.1 ) $ (57.9 ) Foreign (383.3 ) 79.2 78.5 Total earnings before income taxes and discontinued operations $ 19.4 $ 28.1 $ 20.6 Income tax expense for the years ended December 31, 2017 , 2016 , and 2015 is comprised of the following: Years Ended December 31, (in millions) 2017 2016 2015 Current: U.S. Federal $ 28.9 $ — $ 1.9 State and local 0.1 0.1 — Foreign 11.7 6.8 9.9 Total current tax expense $ 40.7 $ 6.9 $ 11.8 Deferred: U.S. Federal $ (26.8 ) $ 0.8 $ (3.5 ) State and local — 0.2 (0.1 ) Foreign (1.0 ) 0.4 (5.0 ) Total deferred tax (benefit) expense (27.8 ) 1.4 (8.6 ) Total income tax expense $ 12.9 $ 8.3 $ 3.2 The reconciliation of the U.S. Federal income tax rate to the Company’s effective income tax rate was as follows: Years Ended December 31, 2017 2016 2015 U.S. Federal income tax rate 35.0 % 35.0 % 35.0 % State and local taxes, net of Federal income tax benefit (0.2 )% 1.1 % (7.4 )% Foreign operations tax effect 27.0 % (22.5 )% (36.6 )% Research & experimentation tax credits (11.6 )% (6.6 )% (12.4 )% Valuation allowance 60.8 % 69.6 % 97.0 % Tax contingencies 6.6 % (0.6 )% (1.3 )% Tax holiday (78.0 )% (64.2 )% (87.9 )% Foreign taxes (5.0 )% 2.8 % 8.8 % Non-deductible transaction costs — % — % 5.9 % Stock-based compensation 9.3 % 9.6 % 4.7 % Other, principally non-tax deductible items (1) 12.7 % 5.1 % 9.5 % Transition tax 89.7 % — % — % Tax reform (85.3 )% — % — % Prior period items 5.5 % 0.2 % 0.2 % Effective income tax rate 66.5 % 29.5 % 15.5 % (1) Includes income tax expense related to the Malaysian tax consequences of the intra-entity intellectual property sale between the U.S. and Malaysia that increases the effective income tax rate by 18.5% for the year ended December 31, 2017. The Company’s effective tax rate is favorably impacted by two tax holidays granted to us by Malaysia effective through December 31, 2021. These tax holidays are subject to the Company’s satisfaction of certain conditions, including investment or sales thresholds, which the Company expects to maintain. During 2016, the Company applied for and received final approval to modify the terms of its main tax holiday in Malaysia, reducing the rate to 7.2% versus the statutory rate of 24.0% , effective January 1, 2017 through December 31, 2021. If the Company fails to satisfy such conditions, the Company’s effective tax rate may be significantly adversely impacted. The continuing operations benefit of these incentives for the years ending December 31, 2017 , 2016 , and 2015 is estimated to be $13.8 million , $16.3 million , and $17.7 million , respectively. The continuing operations benefit of the tax holidays on a per share basis for the years ending December 31, 2017 , 2016 , and 2015 was $0.15 , $0.18 , and $0.20 , respectively. The components of the Company’s deferred tax assets and liabilities included the following: (in millions) December 31, 2017 December 31, 2016 Deferred tax assets: Accrued compensation, principally post-retirement, and other employee benefits $ 13.7 $ 19.0 Accrued expenses, principally for state income taxes, interest, and warranty 5.9 6.5 Net operating loss and other carryforwards 115.6 148.2 Inventories, principally due to reserves for financial reporting purposes and capitalization for tax purposes 3.6 7.5 Convertible Note Hedges 7.3 14.6 Plant and equipment, principally due to differences in depreciation 9.6 4.5 Total gross deferred tax assets 155.7 200.3 Valuation allowance (99.7 ) (161.3 ) Total deferred tax assets $ 56.0 $ 39.0 Deferred tax liabilities: Intangible assets, principally due to different tax and financial reporting bases and amortization lives $ (10.3 ) $ (27.3 ) Debt discount on convertible notes (5.7 ) (11.6 ) Other liabilities (17.6 ) (6.7 ) Total gross deferred tax liabilities (33.6 ) (45.6 ) Net deferred tax asset (liability) $ 22.4 $ (6.6 ) Classified as follows in the Consolidated Balance Sheets: Other assets and deferred charges (non-current deferred tax assets) $ 22.4 $ 15.0 Deferred income taxes (non-current deferred tax liabilities) — (21.6 ) Net deferred tax asset (liability) $ 22.4 $ (6.6 ) The Company recorded valuation allowances of $99.7 million and $161.3 million at December 31, 2017 and 2016 , respectively, against deferred tax assets from continuing operations as the Company believes it is more likely than not that these assets will not be realized. Of the $99.7 million allowance as of December 31, 2017, $11.7 million was related to a change in judgment regarding the realizability of the beginning of the year tax assets as a result of the Tax Reform Act enacted December 22, 2017. Management believes that it is more likely than not that the Company will realize the benefits of the remaining deferred tax assets. The amount of the deferred tax asset is considered realizable, however, it could be adjusted if estimates of future taxable income during the carryforward period are reduced or increased or if objective negative evidence in the form of cumulative losses is no longer present, requiring that additional weight be given to subjective evidence such as our projections for growth. At December 31, 2017 , the Company had $34.2 million of Federal net operating losses that are available, of which $12.2 million will expire in the next 5 to 10 years and $22.0 million will expire in the next 10 to 20 years. There are $96.9 million of State net operating losses that are available between 2018 and 2037. There are $314.2 million of non-U.S. net operating loss carryforwards, of which $3.1 million will expire within the next 5 years, $0.8 million will expire in the next 5 to 10 years, and $310.3 million can be carried forward indefinitely. The Company has $7.7 million of U.S. federal research and development credits that begin to expire in 2020 and $3.3 million of foreign tax credits that begin to expire in 2027 . In addition, the Company has $13.8 million of state credits, of which $1.4 million will expire between 2019 and 2033 if unused, and $12.4 million can be carried forward indefinitely. The Company has not provided for deferred taxes on the undistributed earnings of its international subsidiaries totaling approximately $1.7 billion . Such earnings are reinvested in foreign jurisdictions and it is currently intended that they will continue to be reinvested indefinitely. Our Malaysian principal subsidiary is our primary source of foreign earnings and cash. Any future decision to distribute cash from this subsidiary to the U.S. should not result in a material amount of U.S. or foreign taxes. Unrecognized Tax Benefits The Company records interest and penalties associated with unrecognized tax benefits as a component of income tax expense. During the years ended December 31, 2017 and 2016 , the Company recorded a potential interest benefit of $1.1 million and potential interest expense of $0.3 million , respectively. The Company recorded no potential interest impact during the year ended December 31, 2015 . Total accrued interest at December 31, 2017 , 2016 , and 2015 was $0.4 million , $1.4 million , and $1.3 million , respectively, and was included in other liabilities. During the year ended December 31, 2017, the Company recorded potential penalty expense of $0.2 million , which is also the cumulative penalty amount included in other liabilities. Total accrued penalties at December 31, 2017 was $0.2 million . The Company's tax returns are routinely audited by the tax authorities in the relevant jurisdictions. For tax years before 2014, the Company is no longer subject to U.S. federal income tax examination. For tax years before 2012, the Company’s Malaysian subsidiaries are no longer subject to examination. It is reasonably possible that the gross amount of unrecognized tax benefits will decrease by $2.8 million during the next twelve months. Included in the balance of total unrecognized tax benefits at December 31, 2017 are potential benefits of $6.0 million , which if recognized, would affect the effective rate on earnings from continuing operations. Given the Company's current valuation allowance position, no benefit is expected to result from the reversal of any uncertain tax position associated with the acquired attributes. Unrecognized tax benefits at January 1, 2015 $ 5.0 Reductions for tax positions of prior years (0.4 ) Additions for business combinations 8.4 Foreign exchange fluctuations (0.2 ) Unrecognized tax benefits at December 31, 2015 $ 12.8 Reductions for tax positions due to lapsed statutes of limitations (0.5 ) Foreign exchange fluctuations (0.5 ) Unrecognized tax benefits at December 31, 2016 $ 11.8 Additions based on tax positions related to the current year 2.6 Additions for tax positions of prior years 0.6 Reductions for tax positions due to lapsed statutes of limitations (1.3 ) Tax reform (1.5 ) Foreign exchange fluctuations 0.3 Unrecognized tax benefits at December 31, 2017 $ 12.5 On December 22, 2017, the Tax Reform Act was enacted which permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. As a result of the reduction in the U.S. corporate income tax rate, the Company revalued its ending net deferred tax liabilities as of December 31, 2017 and recognized a provisional tax benefit of $5.6 million . Due to the change in the net operating loss carryforward period, taxable temporary differences associated with our indefinite-lived intangible assets allow the company to recognize $11.7 million of deferred tax assets that previously required a valuation allowance. The Tax Reform Act also provided for a one-time deemed repatriation of post-1986 undistributed foreign subsidiary E&P through the year ended December 31, 2017. The Company recorded provisional tax expense related to the deemed repatriation of $18.0 million payable over nine years. The expected gross payable due to the Tax Reform Act is $25.9 million , which will be reduced by the use of approximately $7.9 million of existing deferred tax assets resulting in an $18.0 million net expected liability as of December 31, 2017. The GILTI provisions of the Tax Reform Act require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company expects that it will be subject to incremental U.S. tax on GILTI income beginning in 2018. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its Consolidated Financial Statements for the year ended December 31, 2017. On December 22, 2017, the SEC staff issued SAB 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. In accordance with the SAB 118 guidance, the Company has recognized the provisional tax impacts related to deemed repatriated earnings, the change in beginning of year valuation allowance, and the benefit for the remeasurement of deferred tax assets and liabilities in its Consolidated Financial Statements for the year ended December 31, 2017. The final impact may differ from these provisional amounts, possibly materially, due to, among other things, issuance of additional regulatory guidance, changes in interpretations and assumptions the Company has made, and actions the Company may take as a result of the Tax Reform Act. In accordance with SAB 118 the financial reporting impact of the Tax Reform Act will be completed in the fourth quarter of 2018.

Equity Incentive Program

Equity Incentive Program	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]	13. Equity Incentive Program The following table summarizes the compensation expense recognized by the Company for the periods presented: Years Ended December 31, (in millions) 2017 2016 2015 Pre-tax stock-based compensation expense $ 24.7 $ 20.9 $ 15.0 Tax benefit — — — Total stock-based compensation expense, net of tax $ 24.7 $ 20.9 $ 15.0 For 2017 , stock-based compensation expense of $16.8 million was classified in Selling and administrative expenses, $6.1 million in Research and development expenses, and $1.8 million in Cost of goods sold. For 2016 , stock-based compensation expense of $14.7 million was classified in Selling and administrative expenses, $4.7 million in Research and development expenses, and $1.5 million in Cost of goods sold. For 2015 , stock-based compensation expense of $11.8 million was classified in Selling and administrative expenses, $1.2 million in Cost of goods sold, and $2.0 million in Research and development expenses. Compensation expense for stock-based awards is measured based on the fair value of the awards as of the date the stock-based awards are granted and adjusted to the estimated number of awards that are expected to vest. Forfeitures are estimated based on historical experience at the time of grant and revised in subsequent periods if actual forfeitures differ from those estimates. Compensation costs for stock-based awards are amortized over their service period. Prior to the Separation, Knowles employees participated in our Former Parent's incentive stock program. Stock-based compensation expense was allocated to Knowles based on the portion of our Former Parent's equity incentive program in which Knowles employees participated. Adopted in connection with the Separation, the Knowles' Corporation 2014 Equity and Cash Incentive Plan (the "Plan") provided for the assumption of certain awards granted under our Former Parent's equity incentive program and authorized the grant of several different forms of benefits, including stock options, RSUs, PSUs, and SSARs. In connection with the Separation, equity awards previously granted by our Former Parent to employees of the Company were converted to Knowles equity awards under the Plan. In general, each award is subject to the same terms and conditions as were in effect prior to the Separation, except that our Former Parent's performance shares converted to time-based RSUs. In addition, the Company made a grant comprised of both stock options and time-based RSUs that vest 50% on the third and fourth anniversaries from the date of the grant. The Company also made grants of both stock options and time-based RSUs that vest evenly over each of the first three years following the date of the grant. Lastly, the independent directors received a grant of Company shares that vested immediately in March 2014 and an annual grant for their service during the year ended December 31, 2014, receipt of which was deferred by some of the recipients. The Company elected to use the straight-line method to attribute the expense over the service period of the awards. In connection with the Audience acquisition, the Company converted unvested in-the-money Audience stock options and RSUs to Knowles equity awards for an aggregate of 461,371 shares of its common stock. The fair value of unvested equity awards relating to future services, and not yet earned, are recorded as operating expenses over the remaining service periods. The Company has elected to use the straight-line method to attribute the expense over the service period of the awards. Stock Option s and SSAR's 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. 2017 2016 2015 Risk-free interest rate 1.73% to 1.93% 1.04% to 1.25% 1.24% to 1.50% Dividend yield —% —% —% Expected life (years) 4.5 4.5 4.5 Volatility 33.2% to 38.8% 37.0% to 39.6% 39.8% to 42.4% Fair value at date of grant $5.02 to $6.73 $3.76 to $4.83 $5.94 to $6.88 The determination of expected volatility is based on a blended peer group volatility for companies in similar industries, stage of life, and with similar market capitalization since there is not sufficient historical volatility data for Knowles common stock over the period commensurate with the expected term of stock options, as well as other relevant factors. The risk-free interest rate is based on U.S. government issues with a remaining term equal to the expected life of the stock options. The expected term is the period over which our employees are expected to hold their options. It is based on the simplified method from the Securities and Exchange Commission’s safe harbor guidelines. The Company does not currently anticipate paying dividends over the expected term. The exercise price per share for the stock options granted by the Company was equal to the closing price of Knowles' stock on the New York Stock Exchange on the date of the grant. The period during which options granted by the Company were exercisable was fixed by Knowles' Compensation Committee of the Board of Directors at the time of grant. Generally, the stock options expire at the end of seven years. The following table summarizes the Company's SSAR and stock option activity for the year ended December 31, 2017 . 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, 2016 898,718 $ 21.25 4,684,117 $ 18.03 Granted — — 832,826 19.02 Exercised (31,665 ) 12.33 (229,028 ) 14.33 Forfeited — — (286,907 ) 15.48 Expired (16,537 ) 23.20 (99,269 ) 24.55 Outstanding at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 4,901,739 $ 18.36 $ 5.7 4.7 Exercisable at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 2,224,961 $ 20.52 $ 1.7 4.2 The aggregate intrinsic value in the table above represents the difference between the Company's closing stock price on December 31, 2017 and the exercise price of each SSAR and stock option, multiplied by the number of in-the-money awards. Unrecognized compensation expense related to stock options not yet exercisable at December 31, 2017 was $7.3 million . This cost is expected to be recognized over a weighted-average period of 1.2 years. There was no unrecognized compensation expense related to SSARs at December 31, 2017 . Other information regarding the exercise of SSARs and stock options is listed below: Years Ended December 31, (in millions) 2017 2016 2015 SSARs Fair value of SSARs that are exercisable $ 1.9 $ 1.9 $ 0.6 Aggregate intrinsic value of SSARs exercised $ 0.2 $ 0.1 $ 0.1 Stock Options Cash received by Knowles for exercise of stock options $ 3.3 $ — $ — Aggregate intrinsic value of options exercised $ 1.1 $ — $ — RSUs The following table summarizes the Company's RSU balances for the year ended December 31, 2017 : Share units Weighted-average grant date fair value Unvested at December 31, 2016 2,074,998 $ 14.94 Granted 1,375,335 18.55 Vested (821,620 ) 16.11 Forfeited (426,137 ) 15.77 Unvested at December 31, 2017 2,202,576 $ 16.54 At December 31, 2017 , $23.1 million of unrecognized compensation expense related to RSUs is expected to be recognized over a weighted-average period of 1.4 years. PSUs In February 2017, the Company granted PSUs to senior management. The PSUs are awards that are subject to both performance and market conditions and provide the recipient with Knowles stock upon vesting. The awards vest three years subsequent to the initial grant date. The performance condition of the award is based on the Company's financial performance while the award's market condition relates to the Company's stock performance. Given the conditional nature of the PSU awards, the recipients can receive an award of the Company's common stock that can range from 0% to 225% of the initial grant value and is based on the level of achievement of the specified conditions. The Company will ratably recognize the expense over the requisite service period of the PSU and adjust the expense as appropriate. The fair value of the PSUs is determined by using a binomial model simulation. The following table summarizes the Company's PSU balances for the year ended December 31, 2017 : Share units Weighted-average grant date fair value Unvested at December 31, 2016 — $ — Granted 176,000 15.32 Vested — — Forfeited — — Unvested at December 31, 2017 176,000 $ 15.32 At December 31, 2017 , $2.0 million of unrecognized compensation expense related to PSUs is expected to be recognized over a weighted-average period of 2.1 years .

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	14. Commitments and Contingent Liabilities From time to time, the Company is involved in various legal proceedings and claims arising in the ordinary course of its business, including those related to intellectual property, which may be owned by it or others. The Company owns many patents covering products, technology, and manufacturing processes. Some of these patents have been and may continue to be challenged by others. In appropriate cases, the Company has taken and will take steps to protect and defend its patents and other intellectual property, including through the use of legal proceedings in various jurisdictions around the world. Such steps have resulted in and may continue to result in retaliatory legal proceedings, including litigation or other legal proceedings in various jurisdictions and forums around the world alleging infringement by the Company of patents owned by others. The costs of investigations and legal proceedings, particularly multi-forum litigation, relating to the enforcement and defense of the Company’s intellectual property, may be substantial. Additionally, in multi-forum disputes, the Company may incur adverse judgments with regard to certain claims in certain jurisdictions and forums while still contesting other related claims against the same opposing party in other jurisdictions and forums. Although the ultimate outcome of any legal proceeding or claim cannot be predicted with certainty, based on present information, including management’s assessment of the merits of the particular claim, the Company does not expect that any asserted or unasserted legal proceedings or claims, individually or in the aggregate, will have a material adverse effect on its cash flow, results of operations, or financial condition. Intellectual Property Infringement Claims The Company may, on a limited customer specific basis, provide contractual indemnities for certain losses that arise out of claims that its products infringe on the intellectual property of others. Historically, the Company has not made significant payments under such indemnity arrangements. The Company’s legal accruals were not significant at December 31, 2017 and 2016 . Lease Commitments The Company leases certain facilities and equipment under operating leases, many of which contain renewal options. Total rental expense for all operating leases, net of sublease rental income, was $6.8 million , $7.8 million , and $10.2 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Total sublease rental income was $2.2 million and $1.3 million for the years ended December 31, 2017 and 2016 , respectively. There was no sublease rental income for the year ended December 31, 2015 . Contingent rentals under the operating leases were not significant. In September 2013, the Company entered into an agreement for two new facilities and related equipment in China. The lease for one of the facilities and related equipment began in the fourth quarter of 2014. The Company took possession of the second facility and remaining equipment in 2015. The facilities are reflected in the operating leases and the equipment is reflected in the capital leases in the table below. The aggregate future minimum lease payments for capital leases, operating leases, and rental commitments as of December 31, 2017 are as follows: (in millions) Capital Leases Operating Leases 2018 $ 2.4 $ 9.2 2019 2.4 8.8 2020 2.4 8.2 2021 2.4 8.0 2022 2.4 7.2 2023 and thereafter 5.3 18.5 Total minimum lease payments 17.3 59.9 Less sublease rental income — (10.5 ) Net minimum lease payments 17.3 $ 49.4 Less imputed interest (2.5 ) Present value of capital lease obligations $ 14.8

Employee Benefit Plans (Notes)

Employee Benefit Plans (Notes)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefit Plans	15. Employee Benefit Plans Knowles sponsors its own defined contribution plan. The Company's expense relating to the defined contribution plan was $6.4 million , $6.1 million , and $5.0 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Knowles sponsors three defined benefit pension plans to certain non-U.S. employees (two in the United Kingdom and one in Taiwan). All three plans are closed to new participants; however, all active participants in these plans continue to accrue benefits. These plans are considered direct obligations of the Company and have been recorded within the accompanying Consolidated Financial Statements. The Company does not have any other post-retirement employee benefit plans other than the plans mentioned above and the non-qualified supplemental retirement plan discussed below. Non-U.S. Defined Benefit Pension Plans Obligations and Funded Status The following tables summarize the balance sheet impact, including the benefit obligations, assets, and funded status associated with the Company's three defined benefit plans for non-U.S. participants at December 31, 2017 and 2016 . December 31, (in millions) 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 52.4 $ 51.0 Service cost 0.3 0.2 Interest cost 1.5 1.6 Benefits paid (1.5 ) (1.7 ) Actuarial loss 0.5 10.1 Plan amendments 0.3 — Settlements and curtailments — (0.2 ) Currency translation and other 4.4 (8.6 ) Benefit obligation at end of year 57.9 52.4 Change in plan assets: Fair value of plan assets at beginning of year 43.8 45.1 Actual return on plan assets 4.4 6.7 Company contributions 1.5 1.7 Benefits paid (1.5 ) (1.7 ) Settlements and curtailments — (0.2 ) Currency translation and other 3.6 (7.8 ) Fair value of plan assets at end of year 51.8 43.8 Funded status $ (6.1 ) $ (8.6 ) Amounts recognized in the Consolidated Balance Sheets consist of: Other assets and deferred charges $ 0.4 $ — Other liabilities (6.5 ) (8.6 ) Funded status $ (6.1 ) $ (8.6 ) Accumulated Other Comprehensive Loss: Net actuarial losses $ 18.4 $ 20.1 Prior service cost 0.3 — Deferred taxes (3.6 ) (3.6 ) Total Accumulated Other Comprehensive Loss, net of tax 15.1 16.5 Net amount recognized $ 9.0 $ 7.9 Accumulated benefit obligation $ 57.0 $ 51.3 Pension plans with accumulated benefit obligations in excess of plan assets consisted of the following at December 31, 2017 and 2016 : December 31, (in millions) 2017 2016 Projected benefit obligation $ 35.3 $ 32.6 Accumulated benefit obligation 34.8 31.9 Fair value of plan assets 28.8 24.2 Net Periodic Benefit Cost (Income) Components of the net periodic benefit cost (income) were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Service cost $ 0.3 $ 0.2 $ 0.2 Interest cost 1.5 1.6 2.0 Expected return on plan assets (2.7 ) (2.4 ) (2.9 ) Amortization of recognized actuarial loss 0.5 0.3 0.4 Settlement and curtailment loss — — 0.1 Total net periodic benefit income $ (0.4 ) $ (0.3 ) $ (0.2 ) The Company expects to amortize an actuarial loss of $0.5 million from accumulated other comprehensive loss into net periodic benefit cost (income) during the year ended December 31, 2018 . Assumptions The Company determines actuarial assumptions on an annual basis. The actuarial assumptions used for the Company’s three defined benefit plans for non-U.S. participants will vary depending on the applicable country and as such, the tables below include these assumptions by country, as well as in total. The assumptions used in determining the benefit obligations were as follows: December 31, 2017 2016 Discount rate Taiwan 1.25 % 1.50 % United Kingdom 2.44 % 2.65 % Weighted-average 2.40 % 2.60 % Average wage increase Taiwan 4.00 % 4.00 % United Kingdom 4.50 % 4.60 % Weighted-average 4.46 % 4.55 % The assumptions used in determining the net periodic benefit cost (income) were as follows: Years Ended December 31, 2017 2016 2015 Discount rate Taiwan 1.50 % 1.10 % 2.00 % United Kingdom 2.64 % 3.90 % 3.75 % Weighted-average 2.60 % 3.72 % 3.66 % Average wage increase Taiwan 4.00 % 4.00 % 4.00 % United Kingdom 4.60 % 4.25 % 4.25 % Weighted-average 4.55 % 4.16 % 4.23 % Expected return on plan assets Taiwan 1.75 % 1.50 % 1.50 % United Kingdom 5.90 % 6.50 % 6.53 % Weighted-average 5.80 % 6.42 % 6.38 % The Company’s discount rate assumption is determined by developing a yield curve based on high quality corporate bonds with maturities matching the plans’ expected benefit payment streams. The plans’ expected cash flows are then discounted by the resulting year-by-year spot rates. Plan Assets The primary financial objective of the plans is to secure participant retirement benefits. Accordingly, the key objective in the plans’ financial management is to promote stability and, to the extent appropriate, growth in the funded status. Related and supporting financial objectives are established in conjunction with a review of current and projected plan financial requirements. As it relates to the funded defined benefit pension plans, the Company’s funding policy is consistent with the funding requirements of applicable local non-U.S. laws. The Company is responsible for overseeing the management of the investments of the plans’ assets and otherwise ensuring that the plans’ investment programs are in compliance with applicable local law, other relevant legislation, and related plan documents. Where relevant, the Company has retained professional investment managers to manage the plans’ assets and implement the investment process. The investment managers, in implementing their investment processes, have the authority and responsibility to select appropriate investments in the asset classes specified by the terms of their applicable prospectus or investment manager agreements with the plans. The assets of the plans are invested to achieve an appropriate return for the plans consistent with a prudent level of risk. The asset return objective is to achieve, as a minimum over time, the passively managed return earned by market index funds, weighted in the proportions outlined by the asset class exposures identified in the plans’ strategic allocation. The expected return on assets assumption used for pension expense is developed through analysis of historical market returns, statistical analysis, current market conditions, and the past experience of plan asset investments. Fair Value Measurements ASC 820, Fair Value Measurement, establishes a fair value hierarchy that requires the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the hierarchy is based on the lowest level of input that is significant to the fair value measurement. ASC 820 establishes three levels of inputs that may be used to measure fair value as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 - Observable inputs other than quoted prices included in Level 1, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities. Level 3 - Unobservable inputs for which little or no market data exists, therefore, requiring an entity to develop its own assumptions. The fair values of plan assets by asset category within the ASC 820 hierarchy were as follows at December 31, 2017 and 2016 : December 31, 2017 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Asset category: Fixed income investments $ 2.3 $ 12.7 $ — $ 15.0 $ 2.5 $ 10.5 $ — $ 13.0 Common stock funds — 21.9 — 21.9 — 18.7 — 18.7 Real estate funds — 3.5 — 3.5 — — — — Cash and equivalents 0.1 0.9 — 1.0 0.2 3.3 — 3.5 Other 6.8 3.6 — 10.4 5.1 3.5 — 8.6 Total $ 9.2 $ 42.6 $ — $ 51.8 $ 7.8 $ 36.0 $ — $ 43.8 There were no significant transfers between Level 1 and Level 2 assets during the years ended December 31, 2017 and 2016 . Fixed income investments include government and municipal securities and corporate bonds, which are valued based on yields currently available on comparable securities of issuers with similar credit ratings. Common stock funds consist of mutual funds and collective trusts. Mutual funds are valued by obtaining quoted prices from nationally recognized securities exchanges. Collective trusts are valued using Net Asset Value (the "NAV") as of the last business day of the year. The NAV is based on the underlying value of the assets owned by the fund minus its liabilities and then divided by the number of shares outstanding. The value of the underlying assets is based on quoted prices in active markets. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Company believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. Future Estimates Benefit Payments Estimated future benefit payments to retirees, which reflect expected future service, are as follows: (in millions) 2018 $ 1.7 2019 1.6 2020 1.7 2021 1.7 2022 1.8 2023-2027 10.9 Contributions Generally, annual contributions are made at such times and in such amounts as required by law and agreed with the trustees of the non-U.S. defined benefit plans. The Company estimates it will pay $1.8 million during the year ended December 31 , 2018 related to contributions to these plans. This amount may vary based on updated funding agreements with the Trustees of these plans. Non-qualified Supplemental Retirement Plan Knowles provides to certain management employees, through non-qualified plans, supplemental retirement benefits in excess of qualified plan limits imposed by federal tax law. Effective December 31, 2013, the Company's participants no longer accrue benefits. The net amount recognized on the balance sheet at December 31, 2017 is shown in the table below: (in millions) December 31, 2017 Accrued compensation and employee benefits $ (0.2 ) Other liabilities (1.6 ) Total Accumulated Other Comprehensive Loss, net of tax 0.2 Net amount recognized $ (1.6 ) The actuarial loss arising during the year ended December 31, 2017 was $0.1 million ( $0.1 million net of tax). The amortization of prior service cost included in net periodic pension cost (income) during the year ended December 31, 2017 was $0.1 million ( $0.1 million net of tax).

Other Comprehensive (Loss) Earn

Other Comprehensive (Loss) Earnings	12 Months Ended
	Dec. 31, 2017
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive (Loss) Earnings	16. Other Comprehensive Earnings (Loss) The amounts recognized in other comprehensive earnings (loss) were as follows: Year Ended December 31, 2017 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ 27.1 $ — $ 27.1 Employee benefit plans 1.3 — 1.3 Changes in fair value of cash flow hedges 4.4 (0.7 ) 3.7 Total other comprehensive earnings $ 32.8 $ (0.7 ) $ 32.1 Year Ended December 31, 2016 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ 0.8 $ — $ 0.8 Employee benefit plans (5.0 ) (0.1 ) (5.1 ) Changes in fair value of cash flow hedges (2.2 ) 0.6 (1.6 ) Total other comprehensive loss $ (6.4 ) $ 0.5 $ (5.9 ) Year Ended December 31, 2015 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ (71.7 ) $ — $ (71.7 ) Employee benefit plans 0.2 — 0.2 Changes in fair value of cash flow hedges (1.4 ) — (1.4 ) Total other comprehensive loss $ (72.9 ) $ — $ (72.9 ) The following table summarizes the changes in balances of each component of accumulated other comprehensive loss, net of tax during the years ended December 31, 2017 and 2016 . (in millions) Cash flow hedges Employee benefit plans Cumulative foreign currency translation adjustments Total Balance at December 31, 2015 $ (1.6 ) $ (11.5 ) $ (113.1 ) $ (126.2 ) Other comprehensive (loss) earnings, net of tax (1.6 ) (5.1 ) 0.8 (5.9 ) Balance at December 31, 2016 (3.2 ) (16.6 ) (112.3 ) (132.1 ) Other comprehensive earnings, net of tax 3.7 1.3 27.1 32.1 Balance at December 31, 2017 $ 0.5 $ (15.3 ) $ (85.2 ) $ (100.0 ) The amounts amortized from accumulated other comprehensive loss to earnings during the year s ended December 31, 2017 , 2016 , and 2015 were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Pension and post-retirement benefit plans: Amortization or settlement of actuarial losses and prior service costs $ 0.6 $ 0.5 $ 0.8 Tax benefit — — — Net of tax $ 0.6 $ 0.5 $ 0.8 Cash flow hedges: Net losses reclassified into earnings $ 0.5 $ 1.0 $ — Tax benefit (0.2 ) (0.1 ) — Net of tax $ 0.3 $ 0.9 $ — The Company recognizes net periodic pension cost (income), which includes amortization of net actuarial losses and prior service costs, in both Selling and administrative expenses and Cost of goods sold, depending on the functional area of the underlying employees included in the plans.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	17. Segment Information In January 2017, the Company changed its allocation of resources and its internal reporting structure to facilitate delivering growth in its core business. The Company’s operating segments engage in business activities from which they earn revenues and incur expenses, have discrete financial information available, and whose financial results are regularly reviewed and used by the chief operating decision maker to evaluate segment performance, allocate resources, and determine management incentive compensation. The Audio segment aggregates two operating segments into one reportable segment based on similar product applications serving our key end markets. The PD segment has one operating segment, which equals its reportable segment. The realignment did not change the composition of the Company’s reporting units for goodwill impairment testing purposes. Given these changes, beginning in January 2017, the Company's two reportable segments are as follows: • Audio Segment Our Audio group designs and manufactures innovative audio products, including microphones and balanced armature speakers, signal processing technologies, and software and algorithms used in applications that serve the mobile, ear, and IoT markets. Locations include the sales, support, and engineering facilities in North America, Europe, and Asia, as well as the manufacturing facilities in Asia. • PD Segment Our PD group specializes in the design and delivery of highly engineered capacitors and RF devices for technically demanding applications. Our devices are used in applications including power supplies, radar, medical implants, and satellites, serving the industrial, defense, aerospace, medical, and telecommunications markets. Locations include sales, support, engineering, and manufacturing facilities in North America, Europe, and Asia. The Company organizes its reportable segments based on how management analyzes performance, allocates capital, and makes strategic and operational decisions. These segments were determined in accordance with ASC 280, Segment Reporting. The segments are aligned around similar product applications serving our key end markets, to enhance focus on end market growth strategies. Historical financial segment information has been recast to conform to the new segment presentation. Information regarding the Company's reportable segments is as follows: Years Ended December 31, (in millions) 2017 2016 2015 Revenues: Audio $ 637.4 $ 661.9 $ 654.3 Precision Devices 106.8 93.8 99.3 Total consolidated revenues $ 744.2 $ 755.7 $ 753.6 Earnings from continuing operations before interest and income taxes: Audio $ 76.1 $ 88.8 $ 84.7 Precision Devices 19.2 12.4 5.4 Total segments 95.3 101.2 90.1 Corporate expense / other 55.3 52.7 56.8 Interest expense, net 20.6 20.4 12.7 Earnings before income taxes and discontinued operations 19.4 28.1 20.6 Provision for income taxes 12.9 8.3 3.2 Earnings from continuing operations $ 6.5 $ 19.8 $ 17.4 Depreciation and amortization: Audio $ 45.2 $ 61.4 $ 65.1 Precision Devices 5.6 4.3 4.6 Corporate 3.0 3.3 2.7 Total $ 53.8 $ 69.0 $ 72.4 Capital expenditures: Audio $ 43.6 $ 27.8 $ 26.5 Precision Devices 5.4 3.1 4.0 Corporate 0.5 1.3 6.3 Total $ 49.5 $ 32.2 $ 36.8 Research and development: Audio $ 89.0 $ 89.2 $ 79.5 Precision Devices 4.2 2.7 3.7 Corporate 0.2 0.1 — Total $ 93.4 $ 92.0 $ 83.2 Information regarding assets of the Company's reportable segments: Total Assets December 31, (in millions) 2017 2016 Audio $ 1,430.9 $ 1,348.5 Precision Devices 103.4 84.1 Corporate / eliminations 13.8 2.3 Discontinued operations 1.7 80.1 Total $ 1,549.8 $ 1,515.0 The following table details revenues by geographic location. Revenues are attributed to regions based on the location of the Company's direct customer, which in some instances is an intermediary and not necessarily the end user. Long-lived assets are comprised of net property, plant, and equipment. These assets have been classified based on the geographic location of where they reside. The Company's businesses are based primarily in Asia, North America, and Europe. Revenues Long-Lived Assets Years Ended December 31, December 31, (in millions) 2017 2016 2015 2017 2016 Asia $ 560.8 $ 578.7 $ 564.9 $ 144.9 $ 130.4 United States 101.3 93.3 103.1 37.2 41.4 Europe 72.3 75.1 77.1 0.9 1.1 Other Americas 4.4 3.1 3.6 — — Other 5.4 5.5 4.9 — — Total $ 744.2 $ 755.7 $ 753.6 $ 183.0 $ 172.9 For the year ended December 31, 2017 , revenues from two customers of the Audio segment, Apple Inc. and Samsung Electronics Co., Ltd., represented approximately 22% and 12% , respectively, of total segment revenues. For the year ended December 31, 2016 , revenues from two customers of the Audio segment, Apple Inc. and Samsung Electronics Co., Ltd., represented approximately 23% and 13% , respectively, of total segment revenues. For the year ended December 31, 2015 , revenues from two customers of the Audio segment, Apple Inc. and Samsung Electronics Co., Ltd., represented approximately 25% and 12% , respectively, of total segment revenues. For the year ended December 31, 2017 , revenues from St. Jude Medical, Inc. of the PD segment represented approximately 10% of total segment revenues. For the years ended December 31, 2016 and 2015 , no single customer represented 10% or more of PD segment revenues.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings per Share	18. Earnings per Share Basic and diluted earnings per share was computed as follows: Years Ended December 31, (in millions, except share and per share amounts) 2017 (1) 2016 (1) 2015 (1)(2) Earnings from continuing operations $ 6.5 $ 19.8 $ 17.4 Earnings (loss) from discontinued operations, net 61.8 (62.1 ) (251.2 ) Net earnings (loss) $ 68.3 $ (42.3 ) $ (233.8 ) Basic earnings (loss) per common share: Earnings from continuing operations $ 0.07 $ 0.22 $ 0.20 Earnings (loss) from discontinued operations, net $ 0.69 $ (0.70 ) $ (2.89 ) Net earnings (loss) $ 0.76 $ (0.48 ) $ (2.69 ) Weighted-average shares outstanding 89,329,794 88,667,098 86,802,828 Diluted earnings (loss) per common share: Earnings from continuing operations $ 0.07 $ 0.22 $ 0.20 Earnings (loss) from discontinued operations, net $ 0.68 $ (0.69 ) $ (2.89 ) Net earnings (loss) $ 0.75 $ (0.47 ) $ (2.69 ) Diluted weighted-average shares outstanding 90,490,007 89,182,967 86,992,254 (1) For the years ended December 31, 2017 , 2016 , and 2015 , the weighted-average number of anti-dilutive potential common shares excluded from the calculation of diluted earnings per share above was 3,944,160 , 5,080,023 , and 3,357,320 , respectively. (2) On July 1, 2015, the Company issued 3.2 million shares to former holders of Audience shares and for the conversion of vested in-the-money Audience stock options. The Company also converted unvested in-the-money Audience stock options and restricted stock units for an aggregate of 461,371 shares of its common stock.

Quarterly Data (Unaudited)

Quarterly Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Data (Unaudited)	19. Quarterly Data (Unaudited) (in millions, except per share amounts) Continuing Operations Net Earnings (Loss) Quarter Revenues Gross Profit Earnings (Loss) Per Share - Basic Per Share - Diluted Earnings (Loss) Per Share - Basic Per Share - Diluted 2017 First $ 168.3 $ 59.3 $ (5.0 ) $ (0.06 ) $ (0.06 ) $ (3.2 ) $ (0.04 ) $ (0.04 ) Second 164.4 63.2 (30.9 ) (0.35 ) (0.35 ) (29.7 ) (0.33 ) (0.33 ) Third 196.0 74.2 10.5 0.12 0.12 15.7 0.18 0.17 Fourth 215.5 89.6 31.9 0.36 0.35 85.5 0.96 0.94 2016 First $ 161.1 $ 59.6 $ (10.8 ) $ (0.12 ) $ (0.12 ) $ (29.4 ) $ (0.33 ) $ (0.33 ) Second 165.2 64.9 (6.8 ) (0.08 ) (0.08 ) (24.6 ) (0.28 ) (0.28 ) Third 216.5 86.2 21.0 0.24 0.24 (7.6 ) (0.08 ) (0.08 ) Fourth 212.9 85.2 16.4 0.18 0.18 19.3 0.21 0.22

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Account	SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS Years Ended December 31, 2017 , 2016 , and 2015 Allowance for Doubtful Accounts (in millions) Balance at Beginning of Year Charged to Cost and (1) Accounts Written Off Balance at End of Year Year Ended December 31, 2017 Allowance for Doubtful Accounts $ 1.5 0.2 (1.0 ) $ 0.7 Year Ended December 31, 2016 Allowance for Doubtful Accounts $ 1.5 0.1 (0.1 ) $ 1.5 Year Ended December 31, 2015 Allowance for Doubtful Accounts $ 0.4 1.1 — $ 1.5 (1) Net of recoveries on previously reserved or written-off balances. Deferred Tax Valuation Allowance (in millions) Balance at Beginning of Year Additions Reductions Balance at End of Year Year Ended December 31, 2017 Deferred Tax Valuation Allowance $ 161.3 — (61.6 ) $ 99.7 Year Ended December 31, 2016 Deferred Tax Valuation Allowance $ 127.4 33.9 — $ 161.3 Year Ended December 31, 2015 Deferred Tax Valuation Allowance $ 48.9 78.5 — $ 127.4

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	Background - Knowles Corporation (NYSE:KN) is a market leader and global supplier of advanced micro-acoustic, audio processing, and precision device solutions, serving the mobile consumer electronics, communications, medical, military, aerospace, and industrial markets. The Company uses its leading position in micro-electro-mechanical systems ("MEMS") microphones and strong capabilities in audio processing technologies to optimize audio systems and improve the user experience in mobile, ear, and Internet of Things ("IoT") applications. Knowles is also the leader in acoustics components used in hearing aids and has a strong position in high-end capacitors. The Company's focus on its customers, combined with its unique technology, proprietary manufacturing techniques, rigorous testing, and global scale, enable the Company to deliver innovative solutions that optimize the user experience. References to "Knowles," "the Company," "we," "our," and "us" refer to Knowles Corporation and its consolidated subsidiaries. In January 2017, the Company changed its allocation of resources and its internal reporting structure to facilitate delivering growth in its core business. Given these changes, beginning in January 2017, the Company's two reportable segments are as follows: • Audio Segment Our Audio group designs and manufactures innovative audio products, including microphones and balanced armature speakers, signal processing technologies, and software and algorithms used in applications that serve the mobile, ear, and IoT markets. Locations include the sales, support, and engineering facilities in North America, Europe, and Asia, as well as the manufacturing facilities in Asia. • Precision Devices ("PD") Segment Our PD group specializes in the design and delivery of highly engineered capacitors and radio frequency devices ("RF") for technically demanding applications. Our devices are used in applications including power supplies, radar, medical implants, and satellites, serving the industrial, defense, aerospace, medical, and telecommunications markets. Locations include the sales, support, engineering, and manufacturing facilities in North America, Europe, and Asia. Financial reporting under this new structure is included within this report on Form 10-K and historical financial segment information has been recast to conform to this new presentation within our financial statements. See Note 17. Segment Information for additional information related to the Company’s segments. The Company was spun-off from Dover Corporation ("Dover" or "Former Parent") in 2014 (the "Separation") and our common stock began trading under the ticker symbol “KN” on the New York Stock Exchange (the “NYSE”) on March 3, 2014. On November 28, 2017, the Company completed its sale of the high-end oscillators business ("Timing Device Business"). On July 7, 2016, the Company completed its sale of the speaker and receiver product line (“Speaker and Receiver Product Line”). In accordance with Accounting Standards Codification ("ASC") 205-20, Presentation of Financial Statements - Discontinued Operations, the results of operations and related assets and liabilities for the Timing Device Business and Speaker and Receiver Product Line have been reclassified as discontinued operations for all periods presented. See Note 2. Disposed and Discontinued Operations for additional information related to the transactions. Financial Statement Presentation - The Consolidated Financial Statements included in this Annual Report on Form 10-K are presented in conformity with U.S. generally accepted accounting principles ("U.S. GAAP").
Use of Estimates	Use of Estimates - The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements and disclosures. These estimates may be adjusted due to changes in future economic, industry, or customer financial conditions, as well as changes in technology or demand. Estimates are used in accounting for, among other items, allowances for doubtful accounts receivable, inventory reserves, restructuring reserves, warranty reserves, pension and post-retirement plans, stock-based compensation, corporate allocations, useful lives for depreciation and amortization of long-lived assets, future cash flows associated with impairment testing for goodwill, indefinite-lived intangible assets and other long-lived assets, deferred tax assets, uncertain income tax positions, changes in tax laws, and contingencies. Actual results may ultimately differ from estimates, although management does not believe such differences would materially affect the financial statements in any individual year. Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the Consolidated Financial Statements in the period that they are determined.
Cash and Cash Equivalents	Cash and Cash Equivalents - Cash and cash equivalents include cash on hand, demand deposits, and temporary cash investments with original maturities less than three months.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts – The Company maintains allowances for estimated losses as a result of customers' inability to make required payments. Management evaluates the aging of the accounts receivable balances, the financial condition of its customers, historical trends, and the time outstanding of specific balances to estimate the amount of accounts receivable that may not be collected in the future and records the appropriate provision.
Inventories	Inventories – Inventories are stated at the lower of cost or net realizable value, determined on the first-in, first-out ("FIFO") basis. The value of inventory may decline as a result of surplus inventory, price reductions, or technological obsolescence. It is the Company’s policy to carry reserves against the carrying value of inventory when items have no future demand (obsolete inventory) and additionally, where inventory items on hand have demand, yet have insufficient forecasted activity to consume the entire stock within a reasonable period. It is the Company’s policy to carry reserves against the carrying value of such at-risk inventory items after considering the nature of the risk and any mitigating factors. Prepaid and Other Current Assets – Prepaid and other current assets at December 31, 2017 includes $10.0 million held in escrow that will be received nine months from the completion of the sale of the Timing Device Business. The remaining balance at December 31, 2017 and 2016 is made up of prepaid insurance, supplier prepayments, prepaid licensing fees, and other miscellaneous prepaid assets, none of which are individually significant.
Property, Plant and Equipment	Property, Plant, and Equipment - Property, plant, and equipment includes the historic cost of land, buildings, equipment, and significant improvements to existing plant and equipment or, in the case of acquisitions, a fair market value appraisal of such assets completed at the time of acquisition. Property, plant, and equipment also includes the cost of purchased software. Expenditures for maintenance, repairs, and minor renewals are expensed as incurred. When property or equipment is sold or otherwise disposed of, the related cost and accumulated depreciation is removed from the respective accounts, and the gain or loss realized on disposition is reflected in earnings. The Company historically depreciates its assets on a straight-line basis over their estimated useful lives as follows: buildings and improvements 5 to 31.5 years; machinery and equipment 1.5 to 7 years; furniture and fixtures 3 to 7 years; vehicles 3 years; and software 3 to 7 years.
Derivative Instruments	Derivative Instruments - The Company uses derivative financial instruments to hedge its exposures to various risks, including interest rate and foreign currency exchange rate risk. The Company does not enter into derivative financial instruments for speculative purposes and does not have a material portfolio of derivative financial instruments. Derivative financial instruments used for hedging purposes must be designated and effective as a hedge of the identified risk exposure at inception of the contract. The Company recognizes all derivatives as either assets or liabilities on the Consolidated Balance Sheet and measures those instruments at fair value. For derivatives designated as hedges of the fair value of assets or liabilities, the changes in fair value of both the derivatives and of the hedged items are recorded in current earnings. For derivatives designated as cash flow hedges, the effective portion of changes in the fair value of the derivatives is recorded as a component of other comprehensive earnings and subsequently recognized in net earnings when the hedged items impact earnings.
Goodwill and Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets - Goodwill represents the excess of purchase consideration over the fair value of the net assets of businesses acquired. Goodwill and certain other intangible assets deemed to have indefinite lives (primarily trademarks) are not amortized. Instead, goodwill and indefinite-lived intangible assets are tested for impairment at least annually, or more frequently if indicators of impairment exist. The Company conducts its annual impairment evaluation in the fourth quarter of each year on October 1. Recoverability of goodwill is measured at the reporting unit level. The Company identified four reporting units for its annual goodwill impairment test. Following the sale of the Timing Device Business on November 28, 2017, the Company has three reporting units. The test compares the fair value of each reporting unit using a discounted cash flow method to its carrying value. Impairment is measured as the amount by which the carrying value of a reporting unit exceeds its fair value. This method uses the Company’s market participant assumptions including projections of future cash flows, determinations of appropriate discount rates, and other assumptions which are considered reasonable and inherent in the discounted cash flow analysis. The projections are based on historical performance and future estimated results. These assumptions require significant judgment and actual results may differ from estimated amounts. The fair value of all of the Company’s reporting units exceeded the carrying values by at least 40% , resulting in no goodwill impairment charges. Potential circumstances that could have a negative effect on the fair value of our reporting units include, but are not limited to, lower than forecasted growth rates or profit margins and changes in the weighted average cost of capital. A reduction in the estimated fair value of the reporting units could trigger an impairment in the future. The Company cannot predict the occurrence of certain events or changes in circumstances that might adversely affect the carrying value of goodwill and intangible assets. In testing its other indefinite-lived intangible assets for impairment, the Company uses a relief from royalty method to calculate and compare the fair value of the intangible asset to its carrying value. This method estimates the fair value of trademarks by calculating the present value of royalty income that could hypothetically be earned by licensing the trademark to a third party over the remaining useful life. Any excess of carrying value over the estimated fair value is recognized as an impairment loss. No impairment of indefinite-lived intangibles was indicated for the years ended December 31, 2017 , 2016 , or 2015 . See Note 7. Goodwill and Other Intangible Assets for additional information on goodwill and indefinite-lived intangible assets. Other Intangible and Long-Lived Assets - Other intangible assets with determinable lives consist primarily of customer relationships, unpatented technology, patents, and trademarks and are amortized over their estimated useful lives, historically ranging from 5 to 15 years. The Company relies on patents and proprietary technology, and seeks patent protection for products and production methods. The Company capitalizes external legal costs incurred in the defense of its patents when it believes that a significant, discernible increase in value will result from the defense and a successful outcome of the legal action is probable. These costs are amortized over the remaining estimated useful life of the patent, which is typically 7 to 10 years. The Company’s assessment of future economic benefit and/or the successful outcome of legal action related to patent defense, which involves considerable management judgment and a different outcome could result in material write-offs of the carrying value of these assets. During the years ended December 31, 2017 and 2016 , the Company capitalized no legal costs related to the defense of its patents. For the year ending December 31, 2015 , the Company capitalized $0.5 million in legal costs related to the defense of its patents.
Long-Lived Assets	Long-lived assets (including intangible assets with determinable lives) are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If an indicator of impairment exists for any grouping of assets, an estimate of undiscounted future cash flows is produced and compared to its carrying value. If an asset is determined to be impaired, the loss is measured by the excess of the carrying amount of the asset over its fair value as determined by an estimate of discounted future cash flows. During 2015, Knowles recorded a pre-tax impairment charge of $191.5 million resulting from the carrying value of the Speaker and Receiver Product Line’s net assets being greater than the fair market value. In addition, Knowles identified other asset impairments related to the Speaker and Receiver Product Line of $4.1 million during the year ended December 31, 2015. See Note 2. Disposed and Discontinued Operations for additional details. During the years ended December 31, 2017 , 2016 , and 2015 , the Company recorded impairments and other charges related to its continuing operations of $ 21.3 million , $0.5 million , and $5.6 million , respectively. See Note 4. Impairments for additional details.
Foreign Currency	Foreign Currency - Assets and liabilities of non-U.S. subsidiaries, where the functional currency is not the U.S. dollar, are translated into U.S. dollars at year-end exchange rates. Revenue and expense items are translated using weighted-average yearly exchange rates. Foreign currency translation gains and losses are included as a component of Accumulated other comprehensive loss. Assets and liabilities of an entity that are denominated in currencies other than an entity’s functional currency are re-measured into the functional currency using end of period exchange rates or historical rates where applicable to certain balances. Gains and losses related to these re-measurements are recorded within the Consolidated Statements of Earnings as a component of Other expense (income), net.
Revenue Recognition	Revenue Recognition - Revenue is recognized when all of the following conditions are satisfied: a) persuasive evidence of an arrangement exists, b) price is fixed or determinable, c) collectability is reasonably assured, and d) delivery has occurred or services have been rendered. The majority of the Company’s revenue is generated through the manufacture and sale of a broad range of specialized products and components, with revenue recognized upon transfer of title and risk of loss. The Company recognizes third-party licensing or royalty income as revenue over the related contract term when collection is reasonably assured. The Company does not have significant service revenue or multiple deliverable arrangements. Revenue is recognized net of customer discounts, rebates, and returns. Rebates are recognized over the contract period based on expected revenue levels. Sales discounts and rebates totaled $9.1 million , $8.7 million , and $9.0 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Returns and allowances totaled $8.5 million , $5.1 million , and $6.7 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.
Stock-Based Compensation	Stock-Based Compensation – The principal awards issued under the stock-based compensation plans include stock options, restricted stock units ("RSUs"), and performance share units ("PSUs"). The cost for such awards is measured at the grant date based on the fair value of the award. The value of the portion of the award that is expected to ultimately vest is generally recognized as expense on a straight-line basis, generally over the explicit service period and is included in Cost of goods sold, Research and development expenses, and Selling and administrative expenses in the Consolidated Statements of Earnings, depending on the functional area of the underlying employees. The Company uses the Black-Scholes valuation model to estimate the fair value of stock options granted to employees. The fair value of each RSU granted is equal to the share price at the date of the grant. The fair value of each PSU is determined using a binomial model simulation. At the time of grant, the Company estimates forfeitures, based on historical experience, in order to estimate the portion of the award that will ultimately vest. See Note 13. Equity Incentive Program for additional information related to the Company’s stock-based compensation.
Income Taxes	Income Taxes - The Company records a provision for income taxes for the anticipated tax consequences of the reported results of operations using the asset and liability method. Under this method, the Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. The Company offsets and presents deferred tax liabilities and assets, as well as any related valuation allowance, as a single non-current amount on the Consolidated Balance Sheets on a jurisdictional basis. The Company establishes valuation allowances for its deferred tax assets if, based on all available positive and negative evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. In making such assessments, significant weight is given to evidence that can be objectively verified. The assessment of the need for a valuation allowance requires considerable judgment on the part of management with respect to the benefits that could be realized from future taxable income, as well as other positive and negative factors. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income, and tax-planning strategies in making this assessment. The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Adjustments are made to these reserves when facts and circumstances change, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on the Company's financial condition and operating results. The provision for income taxes includes the effects of any reserves that are believed to be appropriate, as well as the related net interest and penalties. On December 22, 2017, the U.S. bill commonly referred to as the Tax Cuts and Jobs Act (“Tax Reform Act”) was enacted, which significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system, and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. The Tax Reform Act also provided for a one-time deemed repatriation of post-1986 undistributed foreign subsidiary earnings and profits (“E&P”) through the year ended December 31, 2017. The Global Intangible Low-Taxed Income ("GILTI") provisions of the Tax Reform Act require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company expects that it will be subject to incremental U.S. tax on GILTI income beginning in 2018, due to expense allocations required by the U.S. foreign tax credit rules. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its Consolidated Financial Statements for the year ended December 31, 2017. On December 22, 2017, the Securities and Exchange Commission ("SEC") staff issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. The Company has recognized the provisional tax impacts related to deemed repatriated earnings, the change in the beginning of year valuation allowance, and the benefit for the remeasurement of deferred tax assets and liabilities, and included these amounts in its Consolidated Financial Statements for the year ended December 31, 2017. The final impact may differ from these provisional amounts, possibly materially, due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of the Tax Reform Act. In accordance with SAB 118 the financial reporting impact of the Tax Reform Act will be completed in the fourth quarter of 2018.
Research and development expense	Research and Development Costs – Research and development costs, including qualifying engineering costs, are expensed when incurred.
Revision of Prior Period Financial Statements	Reclassifications - Certain amounts in prior years have been reclassified to conform to the current year presentation. Refer to the Recently Issued Accounting Standards section below.

Disposed and Discontinued Ope27

Disposed and Discontinued Operations Discontinued Operations and Disposal Groups (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations	Management and the Board of Directors periodically conduct strategic reviews of the Company's businesses. On November 28, 2017, the Company completed the sale of the Timing Device Business, part of the Precision Devices segment, to Microsemi Corporation for $130.0 million , plus purchase price adjustments for a net amount of $133.3 million . The Company recorded a gain of $62.3 million as a result of the sale, which included $0.4 million of gain amounts reclassified from Accumulated other comprehensive loss into earnings related to currency translation adjustments. The purchase price includes $10.0 million held in escrow that will be received nine months from the completion of the sale and is recorded in the Prepaid and other current assets line on the Consolidated Balance Sheet. On July 7, 2016, the Company completed the sale of its Speaker and Receiver Product Line for $45.0 million in cash, less purchase price adjustments for a net amount received of $40.6 million . The Company recorded a loss of $25.6 million as a result of the sale, which included $26.9 million of loss amounts reclassified from Accumulated other comprehensive loss into earnings related to currency translation adjustments. The results of operations and financial positions of the Timing Device Business and Speaker and Receiver Product Line have been reclassified to discontinued operations for all periods presented as these disposals represent strategic shifts that have a major effect on the Company's results of operations. Summarized results of the Company's discontinued operations are as follows: Years Ended December 31, (in millions) 2017 2016 2015 Revenues $ 92.2 $ 156.4 $ 331.0 Cost of goods sold 61.5 136.1 319.3 Impairment charges (1) 0.4 0.4 50.1 Restructuring charges - cost of goods sold 0.1 8.9 0.9 Gross profit (loss) 30.2 11.0 (39.3 ) Research and development expenses (1) 7.7 15.1 25.7 Selling and administrative expenses 18.5 26.9 58.3 Impairment charges (1) — — 143.3 Restructuring charges 0.2 3.4 3.5 Operating expenses 26.4 45.4 230.8 Other expense (income), net 1.3 (0.9 ) (0.6 ) (Gain) loss on sale of business (62.3 ) 25.6 — Earnings (loss) from discontinued operations before taxes (2) 64.8 (59.1 ) (269.5 ) Provision for (benefit from) income taxes 3.0 3.0 (18.3 ) Earnings (loss) from discontinued operations, net of tax $ 61.8 $ (62.1 ) $ (251.2 ) (1) The Company evaluates long-lived assets for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. During the fourth quarter of 2015, it was determined that the Speaker and Receiver Product Line lacked a future path to profitability, which included a thorough evaluation of key assumptions including selling prices, product margins, as well as future product demand and suggested that the carrying value of the product line’s assets may be impaired. Through the utilization of undiscounted future cash flows to determine the fair value of the assets, the Company concluded that the fair values of the intangible assets and fixed assets associated with the Speaker and Receiver Product Line were less than their respective carrying values at December 31, 2015. As a result, the Speaker and Receiver Product Line's intangible assets and fixed assets were written down to their fair values and Knowles incurred pre-tax impairment charges of $143.3 million and $48.2 million , respectively. In addition, during the year ended December 31, 2015, Knowles incurred other pre-tax impairment charges of $4.1 million . These impairments were recorded within the discontinued operations line items as follows: $50.1 million in Impairment charges within Gross profit (loss), $2.2 million in Research and development expenses, and $143.3 million in Impairment charges within Operating expenses. (2) The Company's policy is to not allocate interest expense to discontinued operations unless it is directly attributable to the operations. The results of operations of the Timing Device Business and Speaker and Receiver Product Line did not have any such interest expense in the periods presented. Assets and liabilities of discontinued operations are summarized below: (in millions) December 31, 2017 December 31, 2016 Assets of discontinued operations: Cash and cash equivalents $ — $ 2.8 Receivables, net of allowances of nil and $0.4, respectively 1.2 19.2 Inventories, net — 17.4 Prepaid and other current assets 0.5 0.6 Total current assets 1.7 40.0 Property, plant, and equipment, net — 13.3 Goodwill — 23.0 Intangible assets, net — 3.7 Other assets and deferred charges — 0.1 Total assets (1) $ 1.7 $ 80.1 Liabilities of discontinued operations: Accounts payable $ 0.1 $ 9.1 Other current liabilities 5.5 13.6 Total current liabilities 5.6 22.7 Deferred income taxes — 0.1 Other liabilities — 0.9 Total liabilities (1) $ 5.6 $ 23.7 (1) In connection with the sale of the Timing Device Business, the Company retained certain obligations related to employees of the Timing Device Business. This arrangement results in maintaining asset and liability balances, which are expected to be settled in the next 12 months. The following table presents the depreciation, amortization, and capital expenditures related to discontinued operations: Years Ended December 31, (in millions) 2017 2016 2015 Depreciation $ 2.3 $ 3.3 $ 39.4 Amortization of intangible assets $ 1.2 $ 1.4 $ 23.9 Capital expenditures $ 2.1 $ 6.5 $ 26.3 There were no capital expenditures in accounts payable at December 31, 2017 . Capital expenditures included in accounts payable at December 31, 2016 and 2015 were $0.1 million and $1.6 million , respectively.

Acquisition Acquisition (Tables

Acquisition Acquisition (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of Purchase Consideration and Asset Allocation		On July 1, 2015, the Company completed its acquisition of all of the outstanding shares of common stock of Audience, Inc. ("Audience") for a consideration per Share of $2.51 in cash and 0.13207 shares of Knowles common stock pursuant to the Agreement and Plan of Merger dated April 29, 2015. The financial results of Audience were included in our Consolidated Financial Statements beginning July 1, 2015. As a result of the acquisition, the Company issued 3.2 million shares and paid $61.6 million in cash to former holders of Shares and for the conversion of vested in-the-money Audience stock options. The Company also converted unvested in-the-money Audience stock options and RSUs for an aggregate of 461,371 shares of its common stock. The fair value of unvested equity awards relating to future services, and not yet earned, are recorded as operating expenses over the remaining service periods. Total consideration was approximately $92.8 million , net of cash and short-term investments acquired of $30.5 million . The revenues and net losses from Audience operations in the six months ending December 31, 2015 were $19.0 million and $31.6 million , respectively. The total purchase consideration of approximately $123.3 million consists of the following: (in millions, except per share amounts) Cash consideration paid to Audience shareholders and equity award holders $ 61.6 Fair value of shares of Knowles common stock issued to Audience shareholders and equity award holders 60.2 Fair value of RSUs assumed 1.5 Fair value of total consideration $ 123.3
Selected Unaudited Pro-forma Combined Statement of Earnings	Impact of Audience Acquisition and Pro-forma Summary The following unaudited pro-forma summary presents consolidated financial information as if Audience had been acquired on January 1, 2014. The unaudited pro-forma financial information is based on historical results of operations and financial position of the Company and Audience. The pro-forma results include: • estimated amortization of a definite-lived developed technology intangible asset, • the estimated cost of the inventory step-up to fair value, • the estimated depreciation expense of the fixed asset step-up to fair value, • interest expense associated with debt that would have been incurred in connection with the acquisition, and • the reclassification of Audience transaction costs from 2015 to the first quarter of 2014. The unaudited pro-forma financial information does not necessarily represent the results that would have occurred had the acquisition occurred on January 1, 2014. In addition, the unaudited pro-forma information should not be deemed to be indicative of future results. Year Ended December 31, (in millions, except share and per share amounts) 2015 Revenues from continuing operations: As reported $ 753.6 Pro-forma 783.6 Earnings (loss) from continuing operations: As reported $ 17.4 Pro-forma (36.5 ) Basic earnings (loss) per share from continuing operations: As reported $ 0.20 Pro-forma (0.41 ) Diluted earnings (loss) per share from continuing operations: As reported $ 0.20 Pro-forma (0.41 )

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory, Net [Abstract]
Components of Inventory	(in millions) December 31, 2017 December 31, 2016 Raw materials $ 65.9 $ 51.1 Work in progress 21.3 13.3 Finished goods 60.8 51.0 Subtotal 148.0 115.4 Less reserves (22.4 ) (24.6 ) Total $ 125.6 $ 90.8

Property, Plant and Equipment30

Property, Plant and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Components of property, plant and equipment, net	(in millions) December 31, 2017 December 31, 2016 Land $ 7.7 $ 7.7 Buildings and improvements 103.2 93.7 Machinery, equipment, and other 441.1 382.5 Subtotal 552.0 483.9 Less accumulated depreciation (369.0 ) (311.0 ) Total $ 183.0 $ 172.9

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	The changes in the carrying value of goodwill by reportable segment for the years ended December 31, 2017 and 2016 are as follows: (in millions) Audio Precision Devices Total Balance at January 1, 2016 $ 859.2 $ 25.0 $ 884.2 Acquisition adjustment (1) 0.2 — 0.2 Foreign currency translation (12.8 ) — (12.8 ) Balance at December 31, 2016 846.6 25.0 871.6 Foreign currency translation 13.3 — 13.3 Balance at December 31, 2017 $ 859.9 $ 25.0 $ 884.9 (1) Represents goodwill related to the Audience acquisition.
Schedule of Finite-Lived Intangible Assets	The gross carrying value and accumulated amortization for each major class of intangible assets are as follows: December 31, 2017 December 31, 2016 (in millions) Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Amortized intangible assets: Trademarks $ 0.3 $ 0.2 $ 0.3 $ 0.2 Patents 40.8 22.2 40.8 17.5 Customer relationships (1) 3.3 0.7 — — Unpatented technologies (1) (2) 2.4 2.2 28.2 9.8 Other (1) — — — — Total 46.8 25.3 69.3 27.5 Unamortized intangible assets: Trademarks 32.0 32.0 Total intangible assets, net $ 53.5 $ 73.8 (1) During the year ended December 31, 2017, the Company identified an error in which $137.0 million , $53.1 million , and $3.1 million in fully amortized customer relationships, unpatented technologies, and other intangible assets, respectively, should have been written-off during the year ended December 31, 2016. The December 31, 2016 table has been revised to correct the presentation for this matter, which did not impact the Consolidated Balance Sheets or Consolidated Statements of Earnings as presented in the 2016 Form 10-K or any of the 2017 Form 10-Q's. (2) During the year ended December 31, 2017, the Company recorded impairment charges of $16.2 million related to unpatented technologies.
Schedule of Intangible Assets	The gross carrying value and accumulated amortization for each major class of intangible assets are as follows: December 31, 2017 December 31, 2016 (in millions) Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Amortized intangible assets: Trademarks $ 0.3 $ 0.2 $ 0.3 $ 0.2 Patents 40.8 22.2 40.8 17.5 Customer relationships (1) 3.3 0.7 — — Unpatented technologies (1) (2) 2.4 2.2 28.2 9.8 Other (1) — — — — Total 46.8 25.3 69.3 27.5 Unamortized intangible assets: Trademarks 32.0 32.0 Total intangible assets, net $ 53.5 $ 73.8 (1) During the year ended December 31, 2017, the Company identified an error in which $137.0 million , $53.1 million , and $3.1 million in fully amortized customer relationships, unpatented technologies, and other intangible assets, respectively, should have been written-off during the year ended December 31, 2016. The December 31, 2016 table has been revised to correct the presentation for this matter, which did not impact the Consolidated Balance Sheets or Consolidated Statements of Earnings as presented in the 2016 Form 10-K or any of the 2017 Form 10-Q's. (2) During the year ended December 31, 2017, the Company recorded impairment charges of $16.2 million related to unpatented technologies.
Goodwill and Other Intangible Assets	7. Goodwill and Other Intangible Assets The changes in the carrying value of goodwill by reportable segment for the years ended December 31, 2017 and 2016 are as follows: (in millions) Audio Precision Devices Total Balance at January 1, 2016 $ 859.2 $ 25.0 $ 884.2 Acquisition adjustment (1) 0.2 — 0.2 Foreign currency translation (12.8 ) — (12.8 ) Balance at December 31, 2016 846.6 25.0 871.6 Foreign currency translation 13.3 — 13.3 Balance at December 31, 2017 $ 859.9 $ 25.0 $ 884.9 (1) Represents goodwill related to the Audience acquisition. The gross carrying value and accumulated amortization for each major class of intangible assets are as follows: December 31, 2017 December 31, 2016 (in millions) Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Amortized intangible assets: Trademarks $ 0.3 $ 0.2 $ 0.3 $ 0.2 Patents 40.8 22.2 40.8 17.5 Customer relationships (1) 3.3 0.7 — — Unpatented technologies (1) (2) 2.4 2.2 28.2 9.8 Other (1) — — — — Total 46.8 25.3 69.3 27.5 Unamortized intangible assets: Trademarks 32.0 32.0 Total intangible assets, net $ 53.5 $ 73.8 (1) During the year ended December 31, 2017, the Company identified an error in which $137.0 million , $53.1 million , and $3.1 million in fully amortized customer relationships, unpatented technologies, and other intangible assets, respectively, should have been written-off during the year ended December 31, 2016. The December 31, 2016 table has been revised to correct the presentation for this matter, which did not impact the Consolidated Balance Sheets or Consolidated Statements of Earnings as presented in the 2016 Form 10-K or any of the 2017 Form 10-Q's. (2) During the year ended December 31, 2017, the Company recorded impairment charges of $16.2 million related to unpatented technologies. As discussed in Note 3. Acquisitions , the Company completed an acquisition of certain assets of a capacitors manufacturer on January 11, 2017. As a result of this acquisition, the Company acquired a customer list for $3.3 million during the year ended December 31, 2017 , which is included in "Customer relationships" in the table above. The Company is using a five year life to amortize the newly acquired customer list. Total amortization expense for the years ended December 31, 2017 , 2016 , and 2015 was $7.3 million , $18.2 million , and $18.2 million , respectively. Amortization expense is primarily recorded in Selling and administrative expenses in the Consolidated Statements of Earnings. Amortization expense for the next five years, based on current intangible balances, is estimated to be as follows: (in millions) 2018 $ 5.5 2019 5.4 2020 5.3 2021 5.3 2022 —
Schedule of Future Amortization Expense	Amortization expense for the next five years, based on current intangible balances, is estimated to be as follows: (in millions) 2018 $ 5.5 2019 5.4 2020 5.3 2021 5.3 2022 —

Accrued Expenses and Other Li32

Accrued Expenses and Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of Accrued Expenses	The following table details the major components of other accrued expenses: (in millions) December 31, 2017 December 31, 2016 Restructuring and exit costs $ 4.8 $ 2.6 Sales volume rebates 4.7 3.2 Accrued short-term capital leases 2.5 2.4 Accrued taxes other than income taxes 2.4 2.1 Warranty 2.1 1.0 Accrued insurance 1.9 1.6 Hedging liability — 3.6 Other (1) 9.8 5.9 Total $ 28.2 $ 22.4 (1) Represents accrued commissions (non-employee) and other miscellaneous accruals, none of which are individually significant.
Schedule of Other Noncurrent Liabilities	The following table details the major components of other liabilities: (in millions) December 31, 2017 December 31, 2016 Transition tax liability (1) 25.9 — Deferred compensation, including defined benefit plans 18.7 18.7 Long-term capital leases 12.3 13.2 Unrecognized tax benefits 6.5 4.9 Restructuring and exit costs 0.3 0.2 Other 4.2 3.6 Total $ 67.9 $ 40.6
Schedule of Product Warranty Liability	The changes in the carrying amount of product warranties were as follows: Years Ended December 31, (in millions) 2017 2016 Beginning balance, January 1 $ 1.0 $ 1.0 Provision for warranties 2.8 2.5 Settlements made (1.3 ) (2.1 ) Other adjustments, including currency translation (0.4 ) (0.4 ) Ending balance, December 31 $ 2.1 $ 1.0

Restructuring and Related Activ

Restructuring and Related Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities	9. Restructuring and Related Activities Restructuring and related activities are designed to better align the Company's operations with current market conditions through targeted facility consolidations, headcount reductions, and other measures to further optimize operations. During the year ended December 31, 2017 , the Company recorded restructuring charges of $4.0 million within Gross profit for actions primarily associated with transferring certain operations of hearing health manufacturing to a lower-cost Asian manufacturing facility. These charges were recorded within the Audio segment. The Company also recorded restructuring charges of $6.2 million within Operating expenses, primarily for actions associated with rationalizing the research and development workforce. During the year ended December 31, 2016 , the Company recorded restructuring charges of $10.1 million , primarily for actions associated with the integration of Audience, which is reported as part of the Audio segment, and actions associated with rationalizing the selling and administrative workforce. These actions were substantially complete as of December 31, 2016 . In addition, the Company recorded residual charges related to the transfer of a portion of the capacitor business into lower-cost Asian manufacturing facilities, which is reported as part of the PD segment. These charges included severance pay and benefits of $7.5 million and contract termination costs of $2.6 million , of which $1.5 million were classified with Gross profit and $8.6 million were classified within Operating expenses. During the year ended December 31, 2015 , the Company recorded restructuring charges of $9.5 million resulting from its acquisition of Audience, which is reported as part of the Audio segment. These charges included severance pay and benefits of $9.0 million and contract termination costs of $0.5 million . All charges were classified as Operating expenses. The Company also recorded restructuring charges during 2015 related to other actions, which included expenses related to previously announced plans to consolidate its manufacturing footprint, reduce headcount, and other measures to further optimize operations. During the year ended December 31, 2015 , the Company recorded restructuring charges of $4.8 million , which included $4.4 million related to severance pay and benefits and $0.4 million related to contract terminations and other costs, of which $2.7 million were classified within Gross profit and $2.1 million were classified as Operating expenses. Total restructuring charges of $2.7 million were classified within Gross profit and $11.6 million were classified as Operating expenses. The following table details restructuring charges incurred by reportable segment for the periods presented: Years Ended December 31, (in millions) 2017 2016 2015 Audio $ 8.1 $ 7.1 $ 13.4 Precision Devices 0.1 1.4 0.3 Corporate 2.0 1.6 0.6 Total $ 10.2 $ 10.1 $ 14.3 The following table details the Company’s severance and other restructuring accrual activity: (in millions) Severance Pay and Benefits Contract Termination and Other Costs Total Balance at January 1, 2015 $ 6.4 $ 0.5 $ 6.9 Restructuring charges 13.4 0.9 14.3 Payments (11.7 ) (0.2 ) (11.9 ) Other, including foreign currency (0.4 ) (0.1 ) (0.5 ) Balance at December 31, 2015 $ 7.7 $ 1.1 $ 8.8 Restructuring charges 7.5 2.6 10.1 Payments (12.8 ) (3.3 ) (16.1 ) Balance at December 31, 2016 $ 2.4 $ 0.4 $ 2.8 Restructuring charges (1) 8.4 1.8 10.2 Payments (6.5 ) (1.8 ) (8.3 ) Other, including foreign currency 0.4 — 0.4 Balance at December 31, 2017 $ 4.7 $ 0.4 $ 5.1 (1) During the year ended December 31, 2017 , the Company reversed $1.2 million of previously recorded restructuring charges due to subsequent developments that impacted the previously estimated amounts. The severance and restructuring accruals are recorded in the following line items on the Consolidated Balance Sheets: (in millions) December 31, 2017 December 31, 2016 Other accrued expenses $ 4.8 $ 2.6 Other liabilities (1) 0.3 0.2 Total $ 5.1 $ 2.8 (1) This line represents the long-term portion of the charges associated with lease obligations, net of reasonably obtainable sublease income.
Schedule of Restructuring and Related Costs	The following table details restructuring charges incurred by reportable segment for the periods presented: Years Ended December 31, (in millions) 2017 2016 2015 Audio $ 8.1 $ 7.1 $ 13.4 Precision Devices 0.1 1.4 0.3 Corporate 2.0 1.6 0.6 Total $ 10.2 $ 10.1 $ 14.3
Schedule of Restructuring Reserve by Type of Cost	The following table details the Company’s severance and other restructuring accrual activity: (in millions) Severance Pay and Benefits Contract Termination and Other Costs Total Balance at January 1, 2015 $ 6.4 $ 0.5 $ 6.9 Restructuring charges 13.4 0.9 14.3 Payments (11.7 ) (0.2 ) (11.9 ) Other, including foreign currency (0.4 ) (0.1 ) (0.5 ) Balance at December 31, 2015 $ 7.7 $ 1.1 $ 8.8 Restructuring charges 7.5 2.6 10.1 Payments (12.8 ) (3.3 ) (16.1 ) Balance at December 31, 2016 $ 2.4 $ 0.4 $ 2.8 Restructuring charges (1) 8.4 1.8 10.2 Payments (6.5 ) (1.8 ) (8.3 ) Other, including foreign currency 0.4 — 0.4 Balance at December 31, 2017 $ 4.7 $ 0.4 $ 5.1 (1) During the year ended December 31, 2017 , the Company reversed $1.2 million of previously recorded restructuring charges due to subsequent developments that impacted the previously estimated amounts.
Schedule of Restructuring Reserve by Balance Sheet Location	The severance and restructuring accruals are recorded in the following line items on the Consolidated Balance Sheets: (in millions) December 31, 2017 December 31, 2016 Other accrued expenses $ 4.8 $ 2.6 Other liabilities (1) 0.3 0.2 Total $ 5.1 $ 2.8 (1) This line represents the long-term portion of the charges associated with lease obligations, net of reasonably obtainable sublease income.

Hedging Transactions and Deri34

Hedging Transactions and Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table sets forth the fair values of derivative instruments held by the Company as of December 31, 2017 and 2016 and the balance sheet lines to which they are recorded: (in millions) Hedge Type Balance Sheet Line Item December 31, 2017 December 31, 2016 Cash flow hedges Prepaid and other current assets $ 0.6 $ — Cash flow hedges Other accrued expenses — 3.6 Cash flow hedges Other liabilities — 0.2
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance	For economic hedges, for which the Company does not apply hedge accounting, the following (gains) losses were recorded for the years ended December 31, 2017 , 2016 , and 2015 : (in millions) Years Ended December 31, Hedge Type Statement of Earnings Line 2017 2016 2015 Economic Hedges Other expense (income), net $ (0.3 ) $ 2.0 $ 0.3 The following table presents the pre-tax impact of changes in the fair values of the designated derivatives, which qualify for hedge accounting during the years ended December 31, 2017 , 2016 , and 2015 . Knowles reclassified these losses out of AOCI into Other expense (income), net as follows: (in millions) Years Ended December 31, Hedge Type Statement of Earnings Line 2017 2016 2015 Cash flow hedges Other expense (income), net $ 0.5 $ 1.0 $ —

Borrowings and Lines of Credit

Borrowings and Lines of Credit (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Borrowings (net of debt issuance costs, debt discount, and amortization) consist of the following: (in millions) December 31, 2017 December 31, 2016 3.25% Convertible Senior Notes $ 141.9 $ 135.1 Term loan and revolving credit facility 50.7 163.1 Total 192.6 298.2 Less current maturities — 9.7 Total long-term debt $ 192.6 $ 288.5 Total debt principal payments over the next five years are as follows: (in millions) 2018 2019 2020 2021 2022 Debt principal payments (1) $ — $ — $ — $ 172.5 $ 50.7 (1) There are no required principal payments due under the 3.25% Convertible Senior Notes or the revolving credit facility until maturities in November 2021 and October 2022, respectively.
Convertible Debt	3.25% Convertible Senior Notes Due November 1, 2021 In May 2016, the Company issued $172.5 million aggregate principal amount of 3.25% convertible senior notes due November 1, 2021 ("the Notes"), unless earlier repurchased by the Company or converted pursuant to their terms. Interest is payable semiannually in arrears on May 1 and November 1 of each year and commenced on November 1, 2016. The Notes are governed by an Indenture (the "Indenture") between the Company, as issuer, and U.S. Bank National Association as trustee. Upon conversion, the Company will pay or deliver cash, shares of the Company's common stock, or a combination of cash and shares of common stock, at the Company's election. The initial conversion rate is 54.2741 shares of common stock per $1,000 principal amount of Notes. The initial conversion price is $18.4250 per share of common stock. The conversion rate will be subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change (as defined in the Indenture), the Company may be required, in certain circumstances, to increase the conversion rate by a number of additional shares for a holder that elects to convert its Notes in connection with such make-whole fundamental change. Prior to the close of business on the business day immediately preceding August 1, 2021, the Notes will be convertible only under the following circumstances: = during any calendar quarter and only during such calendar quarters, if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; = during the five business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of Notes was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or = upon the occurrence of specified corporate events. On or after August 1, 2021 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their Notes, in multiples of $1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. A s of December 31, 2017 , no event has occurred that would permit the conversion of the Notes. The Notes are the Company’s senior unsecured obligations. In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the face value of the Notes as a whole. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the term of the Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the transaction costs related to the Notes issuance, the Company allocated the total amount incurred to the liability and equity components based on their relative values. Issuance costs attributable to the liability component, totaling $5.0 million , are being amortized to interest expense over the term of the Notes, and issuance costs attributable to the equity component, totaling $1.3 million , were netted with the equity component in stockholders' equity. Additionally, the Company recorded a deferred tax asset of $0.5 million on a portion of the equity component transaction costs which are deductible for tax purposes and immediately recorded a valuation allowance against this deferred tax asset. The Notes consist of the following: (in millions) December 31, 2017 December 31, 2016 Liability component: Principal $ 172.5 $ 172.5 Less debt issuance costs and debt discount, net of amortization (30.6 ) (37.4 ) Total 141.9 135.1 Less current maturities — (0.9 ) Long-term portion $ 141.9 $ 136.0 Equity component (1) $ 29.9 $ 29.9 (1) Recorded in the Consolidated Balance Sheets within additional paid-in capital, inclusive of the $1.3 million of issuance costs in equity. The total estimated fair value of the Notes at December 31, 2017 was $191.4 million . The fair value was determined based on the closing trading price of the Notes as of the last trading day of 2017 . The following table sets forth total interest expense recognized related to the Notes: Years Ended December 31, (in millions) 2017 2016 3.25% coupon $ 5.6 $ 3.7 Amortization of debt issuance costs 0.9 0.6 Amortization of debt discount 5.8 3.6 Total $ 12.3 $ 7.9 Note Hedges To minimize the impact of potential economic dilution upon conversion of the Notes, the Company entered into convertible note hedge transactions (the “Note Hedges”) with respect to its common stock. In the second quarter of 2016, the Company paid an aggregate amount of $44.5 million for the Note Hedges. The Note Hedges will expire upon maturity of the Notes. The Note Hedges are intended to offset the potential dilution upon conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount upon conversion of the Notes in the event that the market value per share of the Company's common stock, as measured under the Note Hedges, is greater than the strike price of the Note Hedges. which initially corresponds to the initial conversion price of the Notes and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of the Notes. The Note Hedges are separate transactions entered into by the Company, and are not part of the Notes or the Warrants, and have been accounted for as part of additional paid-in capital. Holders of the Notes do not have any rights with respect to the Note Hedges. Warrants In addition to the Note Hedges, in the second quarter of 2016, the Company entered into warrant transactions, whereby the Company sold warrants to acquire shares of the Company's common stock at a strike price of $21.1050 per share (the “Warrants”). The Company received aggregate proceeds of $39.1 million from the sale of the Warrants. If the market price per share of the Company's common stock for the reporting period, as measured under the Warrants, exceeds the strike price of the Warrants, the Warrants could have a dilutive effect on the Company's common stock, unless the Company elects, subject to certain conditions, to settle the Warrants in cash. The Warrants are separate transactions entered into by the Company, and are not part of the Notes or the Note Hedges, and have been accounted for as part of additional paid-in capital. Holders of the Notes and Note Hedges do not have any rights with respect to the Warrants.
Schedule of Term Loan and Revolving Credit Facilities	Term Loan and Revolving Credit Facility Term loan and revolving credit facility borrowings consist of the following: (in millions) December 31, 2017 December 31, 2016 Term loan due January 2019 $ — $ 118.5 $300.0 million revolving credit facility due January 2019 — 45.0 $400.0 million revolving credit facility due October 2022 50.7 — Less debt issuance costs, net of amortization — (0.4 ) Total 50.7 163.1 Less current maturities — 10.6 Long-term portion $ 50.7 $ 152.5 On October 11, 2017, Knowles entered into a Revolving Credit Facility Agreement (the "New Credit Facility"). The New Credit Facility contains a five -year senior secured revolving credit facility providing for borrowings in an aggregate principal amount at any time outstanding not to exceed $400.0 million . Up to $100.0 million of the New Credit Facility will be available in Euro, Sterling, and other currencies requested by the Company and agreed to by each Lender and up to $50.0 million of the New Credit Facility will be made available in the form of letters of credit denominated in any currencies agreed by the issuing bank. The New Credit Facility serves as refinancing of indebtedness and terminates the Company's Amended and Restated Credit Agreement dated as of January 27, 2014, as amended and restated as of December 31, 2014 and supplemented from time to time (“Prior Credit Facilities”). At any time during the term of the New Credit Facility, the Company will be permitted to increase the commitments under the New Credit Facility or to establish one or more incremental term loan facilities under the New Credit Facility in an aggregate principal amount not to exceed $200.0 million for all such incremental facilities. Commitments under the New Credit Facility will terminate, and loans outstanding thereunder will mature, on October 11, 2022; provided, that if all the Company’s 3.25% Convertible Senior Notes Due November 1, 2021 have not been repaid, refinanced and/or converted to common stock of the Company by April 30, 2021, then the commitments under the New Credit Facility will terminate, and the loans outstanding thereunder will mature, on such earlier date. The interest rates under the New Credit Facility will be, at the Borrowers’ option (1) LIBOR (or, in the case of borrowings under the New Credit Facility denominated in Euro, EURIBOR) plus the rates per annum determined from time to time based on the total leverage ratio of the Company as of the end of and for the most recent period of four fiscal quarters for which financial statements have been delivered (the “Applicable Rate”); or (2) in the case of borrowings denominated in U.S. dollars, alternate base rate (“ABR”); provided, however, that any swingline borrowings shall bear interest at the rate applicable to ABR borrowings or, prior to the purchase of participations in such borrowings by the Lenders, at such other rate as shall be agreed between the Company and the swingline lender. The interest rate under the New Credit Facility is variable based on LIBOR at the time of the borrowing and the Company’s leverage as measured by a total indebtedness to Consolidated EBITDA ratio. Based upon the Company’s total indebtedness to Consolidated EBITDA ratio, the Company’s borrowing rate could range from LIBOR + 1.25% to LIBOR + 2.25% . In addition, a commitment fee accrues on the average daily unused portion of the New Credit Facility at a rate of 0.20% to 0.35% . The New Credit Facility includes requirements, to be tested quarterly, that the Company maintains (i) a minimum ratio of Consolidated EBITDA to consolidated interest expense of 3.25 to 1.0, (the "Interest Coverage Ratio"), (ii) a maximum ratio of Consolidated total indebtedness to Consolidated EBITDA of 3.75 to 1.0 ("the Leverage Ratio"), and (iii) a maximum ratio of senior secured indebtedness to Consolidated EBITDA of 3.25 to 1.0 (the "Senior Secured Leverage Ratio"). For these ratios, Consolidated EBITDA and consolidated interest expense are calculated using the most recent four consecutive fiscal quarters in a manner defined in the New Credit Facility. At December 31, 2017 , the Company was in compliance with these covenants and it expects to remain in compliance with all of its debt covenants over the next twelve months. On January 27, 2014, the Company entered into a $200.0 million five -year senior secured revolving credit facility as well as a $300.0 million five -year senior secured term loan facility pursuant to the Original Credit Agreement, which are referred to collectively as the "Prior Credit Facilities." On December 31, 2014, the Company amended its Prior Credit Facilities to (i) increase the amount of the revolving credit facility in the Original Credit Agreement to $350.0 million from $200.0 million , (ii) increase the amount of the letter of credit subfacility in the Original Credit Agreement to $50.0 million from $25.0 million , (iii) eliminate the swing line subfacility in the amount of up to $35.0 million in the Original Credit Agreement and (iv) reduce to $100.0 million from $250.0 million the amount of additional incremental revolving or term loans in the Original Credit Agreement. All other terms and conditions of the Prior Credit Facilities remained essentially the same. On February 9, 2016, the Company entered into a third amendment to its Prior Credit Facilities that includes a permanent reduction by the Company of the aggregate revolving commitment under the Prior Credit Facilities from $350.0 million to $300.0 million . On April 27, 2016, the Company entered into a fourth amendment to its Prior Credit Facilities to permit the Company to execute the offering of the Notes and the related transactions. The weighted-average interest rate on the Company's borrowings under the New Credit Facility and Prior Credit Facilities was 3.58% and 3.23% for the years ended December 31, 2017 and 2016 , respectively. The weighted-average interest rate on the Company's borrowings under the New Credit Facility and Prior Credit Facilities for the years ended December 31, 2017 and 2016 includes interest expense related to the monthly interest rate swap settlements. The weighted-average commitment fee on the revolving lines of credit was 0.36% and 0.39% for the years ended December 31, 2017 and 2016 , respectively.
Schedule of Interest Expense and Interest Income	Interest expense and interest income for the years ended December 31, 2017 , 2016 , and 2015 were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Interest expense (1) $ 20.8 $ 20.5 $ 12.8 Interest income (0.2 ) (0.1 ) (0.1 ) Interest expense, net $ 20.6 $ 20.4 $ 12.7 (1) During 2017, the Company wrote off $0.4 million of debt issuance costs related to the Prior Credit Facilities to interest expense upon entering into the New Credit Facility. During 2016, the Company wrote off $0.7 million of debt issuance costs to interest expense in connection with the third amendment to its Prior Credit Facilities.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	The components of earnings before income taxes and discontinued operations were: Years Ended December 31, (in millions) 2017 2016 2015 Domestic $ 402.7 $ (51.1 ) $ (57.9 ) Foreign (383.3 ) 79.2 78.5 Total earnings before income taxes and discontinued operations $ 19.4 $ 28.1 $ 20.6
Schedule of Components of Income Tax Expense (Benefit)	Income tax expense for the years ended December 31, 2017 , 2016 , and 2015 is comprised of the following: Years Ended December 31, (in millions) 2017 2016 2015 Current: U.S. Federal $ 28.9 $ — $ 1.9 State and local 0.1 0.1 — Foreign 11.7 6.8 9.9 Total current tax expense $ 40.7 $ 6.9 $ 11.8 Deferred: U.S. Federal $ (26.8 ) $ 0.8 $ (3.5 ) State and local — 0.2 (0.1 ) Foreign (1.0 ) 0.4 (5.0 ) Total deferred tax (benefit) expense (27.8 ) 1.4 (8.6 ) Total income tax expense $ 12.9 $ 8.3 $ 3.2
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the U.S. Federal income tax rate to the Company’s effective income tax rate was as follows: Years Ended December 31, 2017 2016 2015 U.S. Federal income tax rate 35.0 % 35.0 % 35.0 % State and local taxes, net of Federal income tax benefit (0.2 )% 1.1 % (7.4 )% Foreign operations tax effect 27.0 % (22.5 )% (36.6 )% Research & experimentation tax credits (11.6 )% (6.6 )% (12.4 )% Valuation allowance 60.8 % 69.6 % 97.0 % Tax contingencies 6.6 % (0.6 )% (1.3 )% Tax holiday (78.0 )% (64.2 )% (87.9 )% Foreign taxes (5.0 )% 2.8 % 8.8 % Non-deductible transaction costs — % — % 5.9 % Stock-based compensation 9.3 % 9.6 % 4.7 % Other, principally non-tax deductible items (1) 12.7 % 5.1 % 9.5 % Transition tax 89.7 % — % — % Tax reform (85.3 )% — % — % Prior period items 5.5 % 0.2 % 0.2 % Effective income tax rate 66.5 % 29.5 % 15.5 %
Schedule of Deferred Tax Assets and Liabilities	The components of the Company’s deferred tax assets and liabilities included the following: (in millions) December 31, 2017 December 31, 2016 Deferred tax assets: Accrued compensation, principally post-retirement, and other employee benefits $ 13.7 $ 19.0 Accrued expenses, principally for state income taxes, interest, and warranty 5.9 6.5 Net operating loss and other carryforwards 115.6 148.2 Inventories, principally due to reserves for financial reporting purposes and capitalization for tax purposes 3.6 7.5 Convertible Note Hedges 7.3 14.6 Plant and equipment, principally due to differences in depreciation 9.6 4.5 Total gross deferred tax assets 155.7 200.3 Valuation allowance (99.7 ) (161.3 ) Total deferred tax assets $ 56.0 $ 39.0 Deferred tax liabilities: Intangible assets, principally due to different tax and financial reporting bases and amortization lives $ (10.3 ) $ (27.3 ) Debt discount on convertible notes (5.7 ) (11.6 ) Other liabilities (17.6 ) (6.7 ) Total gross deferred tax liabilities (33.6 ) (45.6 ) Net deferred tax asset (liability) $ 22.4 $ (6.6 ) Classified as follows in the Consolidated Balance Sheets: Other assets and deferred charges (non-current deferred tax assets) $ 22.4 $ 15.0 Deferred income taxes (non-current deferred tax liabilities) — (21.6 ) Net deferred tax asset (liability) $ 22.4 $ (6.6 )
Schedule of Unrecognized Tax Benefits Roll Forward	Unrecognized Tax Benefits The Company records interest and penalties associated with unrecognized tax benefits as a component of income tax expense. During the years ended December 31, 2017 and 2016 , the Company recorded a potential interest benefit of $1.1 million and potential interest expense of $0.3 million , respectively. The Company recorded no potential interest impact during the year ended December 31, 2015 . Total accrued interest at December 31, 2017 , 2016 , and 2015 was $0.4 million , $1.4 million , and $1.3 million , respectively, and was included in other liabilities. During the year ended December 31, 2017, the Company recorded potential penalty expense of $0.2 million , which is also the cumulative penalty amount included in other liabilities. Total accrued penalties at December 31, 2017 was $0.2 million . The Company's tax returns are routinely audited by the tax authorities in the relevant jurisdictions. For tax years before 2014, the Company is no longer subject to U.S. federal income tax examination. For tax years before 2012, the Company’s Malaysian subsidiaries are no longer subject to examination. It is reasonably possible that the gross amount of unrecognized tax benefits will decrease by $2.8 million during the next twelve months. Included in the balance of total unrecognized tax benefits at December 31, 2017 are potential benefits of $6.0 million , which if recognized, would affect the effective rate on earnings from continuing operations. Given the Company's current valuation allowance position, no benefit is expected to result from the reversal of any uncertain tax position associated with the acquired attributes. Unrecognized tax benefits at January 1, 2015 $ 5.0 Reductions for tax positions of prior years (0.4 ) Additions for business combinations 8.4 Foreign exchange fluctuations (0.2 ) Unrecognized tax benefits at December 31, 2015 $ 12.8 Reductions for tax positions due to lapsed statutes of limitations (0.5 ) Foreign exchange fluctuations (0.5 ) Unrecognized tax benefits at December 31, 2016 $ 11.8 Additions based on tax positions related to the current year 2.6 Additions for tax positions of prior years 0.6 Reductions for tax positions due to lapsed statutes of limitations (1.3 ) Tax reform (1.5 ) Foreign exchange fluctuations 0.3 Unrecognized tax benefits at December 31, 2017 $ 12.5

Equity Incentive Program (Table

Equity Incentive Program (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-Based Compensation Recognized Period Costs	The following table summarizes the compensation expense recognized by the Company for the periods presented: Years Ended December 31, (in millions) 2017 2016 2015 Pre-tax stock-based compensation expense $ 24.7 $ 20.9 $ 15.0 Tax benefit — — — Total stock-based compensation expense, net of tax $ 24.7 $ 20.9 $ 15.0
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. 2017 2016 2015 Risk-free interest rate 1.73% to 1.93% 1.04% to 1.25% 1.24% to 1.50% Dividend yield —% —% —% Expected life (years) 4.5 4.5 4.5 Volatility 33.2% to 38.8% 37.0% to 39.6% 39.8% to 42.4% Fair value at date of grant $5.02 to $6.73 $3.76 to $4.83 $5.94 to $6.88
Schedule of SSAR and Stock Options Activity	The following table summarizes the Company's SSAR and stock option activity for the year ended December 31, 2017 . 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, 2016 898,718 $ 21.25 4,684,117 $ 18.03 Granted — — 832,826 19.02 Exercised (31,665 ) 12.33 (229,028 ) 14.33 Forfeited — — (286,907 ) 15.48 Expired (16,537 ) 23.20 (99,269 ) 24.55 Outstanding at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 4,901,739 $ 18.36 $ 5.7 4.7 Exercisable at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 2,224,961 $ 20.52 $ 1.7 4.2
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) 2017 2016 2015 SSARs Fair value of SSARs that are exercisable $ 1.9 $ 1.9 $ 0.6 Aggregate intrinsic value of SSARs exercised $ 0.2 $ 0.1 $ 0.1 Stock Options Cash received by Knowles for exercise of stock options $ 3.3 $ — $ — Aggregate intrinsic value of options exercised $ 1.1 $ — $ —
Schedule of Restricted Stock Units Award Activity	The following table summarizes the Company's RSU balances for the year ended December 31, 2017 : Share units Weighted-average grant date fair value Unvested at December 31, 2016 2,074,998 $ 14.94 Granted 1,375,335 18.55 Vested (821,620 ) 16.11 Forfeited (426,137 ) 15.77 Unvested at December 31, 2017 2,202,576 $ 16.54
Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]	13. Equity Incentive Program The following table summarizes the compensation expense recognized by the Company for the periods presented: Years Ended December 31, (in millions) 2017 2016 2015 Pre-tax stock-based compensation expense $ 24.7 $ 20.9 $ 15.0 Tax benefit — — — Total stock-based compensation expense, net of tax $ 24.7 $ 20.9 $ 15.0 For 2017 , stock-based compensation expense of $16.8 million was classified in Selling and administrative expenses, $6.1 million in Research and development expenses, and $1.8 million in Cost of goods sold. For 2016 , stock-based compensation expense of $14.7 million was classified in Selling and administrative expenses, $4.7 million in Research and development expenses, and $1.5 million in Cost of goods sold. For 2015 , stock-based compensation expense of $11.8 million was classified in Selling and administrative expenses, $1.2 million in Cost of goods sold, and $2.0 million in Research and development expenses. Compensation expense for stock-based awards is measured based on the fair value of the awards as of the date the stock-based awards are granted and adjusted to the estimated number of awards that are expected to vest. Forfeitures are estimated based on historical experience at the time of grant and revised in subsequent periods if actual forfeitures differ from those estimates. Compensation costs for stock-based awards are amortized over their service period. Prior to the Separation, Knowles employees participated in our Former Parent's incentive stock program. Stock-based compensation expense was allocated to Knowles based on the portion of our Former Parent's equity incentive program in which Knowles employees participated. Adopted in connection with the Separation, the Knowles' Corporation 2014 Equity and Cash Incentive Plan (the "Plan") provided for the assumption of certain awards granted under our Former Parent's equity incentive program and authorized the grant of several different forms of benefits, including stock options, RSUs, PSUs, and SSARs. In connection with the Separation, equity awards previously granted by our Former Parent to employees of the Company were converted to Knowles equity awards under the Plan. In general, each award is subject to the same terms and conditions as were in effect prior to the Separation, except that our Former Parent's performance shares converted to time-based RSUs. In addition, the Company made a grant comprised of both stock options and time-based RSUs that vest 50% on the third and fourth anniversaries from the date of the grant. The Company also made grants of both stock options and time-based RSUs that vest evenly over each of the first three years following the date of the grant. Lastly, the independent directors received a grant of Company shares that vested immediately in March 2014 and an annual grant for their service during the year ended December 31, 2014, receipt of which was deferred by some of the recipients. The Company elected to use the straight-line method to attribute the expense over the service period of the awards. In connection with the Audience acquisition, the Company converted unvested in-the-money Audience stock options and RSUs to Knowles equity awards for an aggregate of 461,371 shares of its common stock. The fair value of unvested equity awards relating to future services, and not yet earned, are recorded as operating expenses over the remaining service periods. The Company has elected to use the straight-line method to attribute the expense over the service period of the awards. Stock Option s and SSAR's 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. 2017 2016 2015 Risk-free interest rate 1.73% to 1.93% 1.04% to 1.25% 1.24% to 1.50% Dividend yield —% —% —% Expected life (years) 4.5 4.5 4.5 Volatility 33.2% to 38.8% 37.0% to 39.6% 39.8% to 42.4% Fair value at date of grant $5.02 to $6.73 $3.76 to $4.83 $5.94 to $6.88 The determination of expected volatility is based on a blended peer group volatility for companies in similar industries, stage of life, and with similar market capitalization since there is not sufficient historical volatility data for Knowles common stock over the period commensurate with the expected term of stock options, as well as other relevant factors. The risk-free interest rate is based on U.S. government issues with a remaining term equal to the expected life of the stock options. The expected term is the period over which our employees are expected to hold their options. It is based on the simplified method from the Securities and Exchange Commission’s safe harbor guidelines. The Company does not currently anticipate paying dividends over the expected term. The exercise price per share for the stock options granted by the Company was equal to the closing price of Knowles' stock on the New York Stock Exchange on the date of the grant. The period during which options granted by the Company were exercisable was fixed by Knowles' Compensation Committee of the Board of Directors at the time of grant. Generally, the stock options expire at the end of seven years. The following table summarizes the Company's SSAR and stock option activity for the year ended December 31, 2017 . 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, 2016 898,718 $ 21.25 4,684,117 $ 18.03 Granted — — 832,826 19.02 Exercised (31,665 ) 12.33 (229,028 ) 14.33 Forfeited — — (286,907 ) 15.48 Expired (16,537 ) 23.20 (99,269 ) 24.55 Outstanding at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 4,901,739 $ 18.36 $ 5.7 4.7 Exercisable at December 31, 2017 850,516 $ 21.54 $ 0.1 4.0 2,224,961 $ 20.52 $ 1.7 4.2 The aggregate intrinsic value in the table above represents the difference between the Company's closing stock price on December 31, 2017 and the exercise price of each SSAR and stock option, multiplied by the number of in-the-money awards. Unrecognized compensation expense related to stock options not yet exercisable at December 31, 2017 was $7.3 million . This cost is expected to be recognized over a weighted-average period of 1.2 years. There was no unrecognized compensation expense related to SSARs at December 31, 2017 . Other information regarding the exercise of SSARs and stock options is listed below: Years Ended December 31, (in millions) 2017 2016 2015 SSARs Fair value of SSARs that are exercisable $ 1.9 $ 1.9 $ 0.6 Aggregate intrinsic value of SSARs exercised $ 0.2 $ 0.1 $ 0.1 Stock Options Cash received by Knowles for exercise of stock options $ 3.3 $ — $ — Aggregate intrinsic value of options exercised $ 1.1 $ — $ — RSUs The following table summarizes the Company's RSU balances for the year ended December 31, 2017 : Share units Weighted-average grant date fair value Unvested at December 31, 2016 2,074,998 $ 14.94 Granted 1,375,335 18.55 Vested (821,620 ) 16.11 Forfeited (426,137 ) 15.77 Unvested at December 31, 2017 2,202,576 $ 16.54 At December 31, 2017 , $23.1 million of unrecognized compensation expense related to RSUs is expected to be recognized over a weighted-average period of 1.4 years. PSUs In February 2017, the Company granted PSUs to senior management. The PSUs are awards that are subject to both performance and market conditions and provide the recipient with Knowles stock upon vesting. The awards vest three years subsequent to the initial grant date. The performance condition of the award is based on the Company's financial performance while the award's market condition relates to the Company's stock performance. Given the conditional nature of the PSU awards, the recipients can receive an award of the Company's common stock that can range from 0% to 225% of the initial grant value and is based on the level of achievement of the specified conditions. The Company will ratably recognize the expense over the requisite service period of the PSU and adjust the expense as appropriate. The fair value of the PSUs is determined by using a binomial model simulation. The following table summarizes the Company's PSU balances for the year ended December 31, 2017 : Share units Weighted-average grant date fair value Unvested at December 31, 2016 — $ — Granted 176,000 15.32 Vested — — Forfeited — — Unvested at December 31, 2017 176,000 $ 15.32 At December 31, 2017 , $2.0 million of unrecognized compensation expense related to PSUs is expected to be recognized over a weighted-average period of 2.1 years .

Commitments and Contingent Li38

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments and Rental Commitments	The aggregate future minimum lease payments for capital leases, operating leases, and rental commitments as of December 31, 2017 are as follows: (in millions) Capital Leases Operating Leases 2018 $ 2.4 $ 9.2 2019 2.4 8.8 2020 2.4 8.2 2021 2.4 8.0 2022 2.4 7.2 2023 and thereafter 5.3 18.5 Total minimum lease payments 17.3 59.9 Less sublease rental income — (10.5 ) Net minimum lease payments 17.3 $ 49.4 Less imputed interest (2.5 ) Present value of capital lease obligations $ 14.8

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Schedule of Plan Obligations and Funded Status	The following tables summarize the balance sheet impact, including the benefit obligations, assets, and funded status associated with the Company's three defined benefit plans for non-U.S. participants at December 31, 2017 and 2016 . December 31, (in millions) 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 52.4 $ 51.0 Service cost 0.3 0.2 Interest cost 1.5 1.6 Benefits paid (1.5 ) (1.7 ) Actuarial loss 0.5 10.1 Plan amendments 0.3 — Settlements and curtailments — (0.2 ) Currency translation and other 4.4 (8.6 ) Benefit obligation at end of year 57.9 52.4 Change in plan assets: Fair value of plan assets at beginning of year 43.8 45.1 Actual return on plan assets 4.4 6.7 Company contributions 1.5 1.7 Benefits paid (1.5 ) (1.7 ) Settlements and curtailments — (0.2 ) Currency translation and other 3.6 (7.8 ) Fair value of plan assets at end of year 51.8 43.8 Funded status $ (6.1 ) $ (8.6 ) Amounts recognized in the Consolidated Balance Sheets consist of: Other assets and deferred charges $ 0.4 $ — Other liabilities (6.5 ) (8.6 ) Funded status $ (6.1 ) $ (8.6 ) Accumulated Other Comprehensive Loss: Net actuarial losses $ 18.4 $ 20.1 Prior service cost 0.3 — Deferred taxes (3.6 ) (3.6 ) Total Accumulated Other Comprehensive Loss, net of tax 15.1 16.5 Net amount recognized $ 9.0 $ 7.9 Accumulated benefit obligation $ 57.0 $ 51.3
Schedule of Accumulated Benefit Obligations in Excess of Plan Assets	Pension plans with accumulated benefit obligations in excess of plan assets consisted of the following at December 31, 2017 and 2016 : December 31, (in millions) 2017 2016 Projected benefit obligation $ 35.3 $ 32.6 Accumulated benefit obligation 34.8 31.9 Fair value of plan assets 28.8 24.2
Schedule of Net Periodic Benefit Costs	Components of the net periodic benefit cost (income) were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Service cost $ 0.3 $ 0.2 $ 0.2 Interest cost 1.5 1.6 2.0 Expected return on plan assets (2.7 ) (2.4 ) (2.9 ) Amortization of recognized actuarial loss 0.5 0.3 0.4 Settlement and curtailment loss — — 0.1 Total net periodic benefit income $ (0.4 ) $ (0.3 ) $ (0.2 )
Schedule of Assumptions Used	The assumptions used in determining the benefit obligations were as follows: December 31, 2017 2016 Discount rate Taiwan 1.25 % 1.50 % United Kingdom 2.44 % 2.65 % Weighted-average 2.40 % 2.60 % Average wage increase Taiwan 4.00 % 4.00 % United Kingdom 4.50 % 4.60 % Weighted-average 4.46 % 4.55 % The assumptions used in determining the net periodic benefit cost (income) were as follows: Years Ended December 31, 2017 2016 2015 Discount rate Taiwan 1.50 % 1.10 % 2.00 % United Kingdom 2.64 % 3.90 % 3.75 % Weighted-average 2.60 % 3.72 % 3.66 % Average wage increase Taiwan 4.00 % 4.00 % 4.00 % United Kingdom 4.60 % 4.25 % 4.25 % Weighted-average 4.55 % 4.16 % 4.23 % Expected return on plan assets Taiwan 1.75 % 1.50 % 1.50 % United Kingdom 5.90 % 6.50 % 6.53 % Weighted-average 5.80 % 6.42 % 6.38 %
Fair Value of Plan Assets by Asset Category	The fair values of plan assets by asset category within the ASC 820 hierarchy were as follows at December 31, 2017 and 2016 : December 31, 2017 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Asset category: Fixed income investments $ 2.3 $ 12.7 $ — $ 15.0 $ 2.5 $ 10.5 $ — $ 13.0 Common stock funds — 21.9 — 21.9 — 18.7 — 18.7 Real estate funds — 3.5 — 3.5 — — — — Cash and equivalents 0.1 0.9 — 1.0 0.2 3.3 — 3.5 Other 6.8 3.6 — 10.4 5.1 3.5 — 8.6 Total $ 9.2 $ 42.6 $ — $ 51.8 $ 7.8 $ 36.0 $ — $ 43.8
Schedule of Expected Benefit Payments	Estimated future benefit payments to retirees, which reflect expected future service, are as follows: (in millions) 2018 $ 1.7 2019 1.6 2020 1.7 2021 1.7 2022 1.8 2023-2027 10.9
Non-Qualified Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Schedule of Amounts Recognized in Balance Sheet	Non-qualified Supplemental Retirement Plan Knowles provides to certain management employees, through non-qualified plans, supplemental retirement benefits in excess of qualified plan limits imposed by federal tax law. Effective December 31, 2013, the Company's participants no longer accrue benefits. The net amount recognized on the balance sheet at December 31, 2017 is shown in the table below: (in millions) December 31, 2017 Accrued compensation and employee benefits $ (0.2 ) Other liabilities (1.6 ) Total Accumulated Other Comprehensive Loss, net of tax 0.2 Net amount recognized $ (1.6 )

Other Comprehensive (Loss) Ea40

Other Comprehensive (Loss) Earnings (Tables)	12 Months Ended
	Dec. 31, 2017
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Amounts Recognized in Other Comprehensive Income	The amounts recognized in other comprehensive earnings (loss) were as follows: Year Ended December 31, 2017 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ 27.1 $ — $ 27.1 Employee benefit plans 1.3 — 1.3 Changes in fair value of cash flow hedges 4.4 (0.7 ) 3.7 Total other comprehensive earnings $ 32.8 $ (0.7 ) $ 32.1 Year Ended December 31, 2016 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ 0.8 $ — $ 0.8 Employee benefit plans (5.0 ) (0.1 ) (5.1 ) Changes in fair value of cash flow hedges (2.2 ) 0.6 (1.6 ) Total other comprehensive loss $ (6.4 ) $ 0.5 $ (5.9 ) Year Ended December 31, 2015 (in millions) Pre-tax Tax Net of tax Foreign currency translation $ (71.7 ) $ — $ (71.7 ) Employee benefit plans 0.2 — 0.2 Changes in fair value of cash flow hedges (1.4 ) — (1.4 ) Total other comprehensive loss $ (72.9 ) $ — $ (72.9 )
Schedule of Components of Accumulated Other Comprehensive Income (Loss)	The amounts amortized from accumulated other comprehensive loss to earnings during the year s ended December 31, 2017 , 2016 , and 2015 were as follows: Years Ended December 31, (in millions) 2017 2016 2015 Pension and post-retirement benefit plans: Amortization or settlement of actuarial losses and prior service costs $ 0.6 $ 0.5 $ 0.8 Tax benefit — — — Net of tax $ 0.6 $ 0.5 $ 0.8 Cash flow hedges: Net losses reclassified into earnings $ 0.5 $ 1.0 $ — Tax benefit (0.2 ) (0.1 ) — Net of tax $ 0.3 $ 0.9 $ — The Company recognizes net periodic pension cost (income), which includes amortization of net actuarial losses and prior service costs, in both Selling and administrative expenses and Cost of goods sold, depending on the functional area of the underlying employees included in the plans. The following table summarizes the changes in balances of each component of accumulated other comprehensive loss, net of tax during the years ended December 31, 2017 and 2016 . (in millions) Cash flow hedges Employee benefit plans Cumulative foreign currency translation adjustments Total Balance at December 31, 2015 $ (1.6 ) $ (11.5 ) $ (113.1 ) $ (126.2 ) Other comprehensive (loss) earnings, net of tax (1.6 ) (5.1 ) 0.8 (5.9 ) Balance at December 31, 2016 (3.2 ) (16.6 ) (112.3 ) (132.1 ) Other comprehensive earnings, net of tax 3.7 1.3 27.1 32.1 Balance at December 31, 2017 $ 0.5 $ (15.3 ) $ (85.2 ) $ (100.0 )

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Revenue and Earnings from continuing operations by market segment	Information regarding the Company's reportable segments is as follows: Years Ended December 31, (in millions) 2017 2016 2015 Revenues: Audio $ 637.4 $ 661.9 $ 654.3 Precision Devices 106.8 93.8 99.3 Total consolidated revenues $ 744.2 $ 755.7 $ 753.6 Earnings from continuing operations before interest and income taxes: Audio $ 76.1 $ 88.8 $ 84.7 Precision Devices 19.2 12.4 5.4 Total segments 95.3 101.2 90.1 Corporate expense / other 55.3 52.7 56.8 Interest expense, net 20.6 20.4 12.7 Earnings before income taxes and discontinued operations 19.4 28.1 20.6 Provision for income taxes 12.9 8.3 3.2 Earnings from continuing operations $ 6.5 $ 19.8 $ 17.4 Depreciation and amortization: Audio $ 45.2 $ 61.4 $ 65.1 Precision Devices 5.6 4.3 4.6 Corporate 3.0 3.3 2.7 Total $ 53.8 $ 69.0 $ 72.4 Capital expenditures: Audio $ 43.6 $ 27.8 $ 26.5 Precision Devices 5.4 3.1 4.0 Corporate 0.5 1.3 6.3 Total $ 49.5 $ 32.2 $ 36.8 Research and development: Audio $ 89.0 $ 89.2 $ 79.5 Precision Devices 4.2 2.7 3.7 Corporate 0.2 0.1 — Total $ 93.4 $ 92.0 $ 83.2 Information regarding assets of the Company's reportable segments: Total Assets December 31, (in millions) 2017 2016 Audio $ 1,430.9 $ 1,348.5 Precision Devices 103.4 84.1 Corporate / eliminations 13.8 2.3 Discontinued operations 1.7 80.1 Total $ 1,549.8 $ 1,515.0
Revenue from External Customers by Geographic Areas	The following table details revenues by geographic location. Revenues are attributed to regions based on the location of the Company's direct customer, which in some instances is an intermediary and not necessarily the end user. Long-lived assets are comprised of net property, plant, and equipment. These assets have been classified based on the geographic location of where they reside. The Company's businesses are based primarily in Asia, North America, and Europe. Revenues Long-Lived Assets Years Ended December 31, December 31, (in millions) 2017 2016 2015 2017 2016 Asia $ 560.8 $ 578.7 $ 564.9 $ 144.9 $ 130.4 United States 101.3 93.3 103.1 37.2 41.4 Europe 72.3 75.1 77.1 0.9 1.1 Other Americas 4.4 3.1 3.6 — — Other 5.4 5.5 4.9 — — Total $ 744.2 $ 755.7 $ 753.6 $ 183.0 $ 172.9

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of information used in computing basic and diluted earnings per share	Basic and diluted earnings per share was computed as follows: Years Ended December 31, (in millions, except share and per share amounts) 2017 (1) 2016 (1) 2015 (1)(2) Earnings from continuing operations $ 6.5 $ 19.8 $ 17.4 Earnings (loss) from discontinued operations, net 61.8 (62.1 ) (251.2 ) Net earnings (loss) $ 68.3 $ (42.3 ) $ (233.8 ) Basic earnings (loss) per common share: Earnings from continuing operations $ 0.07 $ 0.22 $ 0.20 Earnings (loss) from discontinued operations, net $ 0.69 $ (0.70 ) $ (2.89 ) Net earnings (loss) $ 0.76 $ (0.48 ) $ (2.69 ) Weighted-average shares outstanding 89,329,794 88,667,098 86,802,828 Diluted earnings (loss) per common share: Earnings from continuing operations $ 0.07 $ 0.22 $ 0.20 Earnings (loss) from discontinued operations, net $ 0.68 $ (0.69 ) $ (2.89 ) Net earnings (loss) $ 0.75 $ (0.47 ) $ (2.69 ) Diluted weighted-average shares outstanding 90,490,007 89,182,967 86,992,254

Quarterly Data (Tables)

Quarterly Data (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	(in millions, except per share amounts) Continuing Operations Net Earnings (Loss) Quarter Revenues Gross Profit Earnings (Loss) Per Share - Basic Per Share - Diluted Earnings (Loss) Per Share - Basic Per Share - Diluted 2017 First $ 168.3 $ 59.3 $ (5.0 ) $ (0.06 ) $ (0.06 ) $ (3.2 ) $ (0.04 ) $ (0.04 ) Second 164.4 63.2 (30.9 ) (0.35 ) (0.35 ) (29.7 ) (0.33 ) (0.33 ) Third 196.0 74.2 10.5 0.12 0.12 15.7 0.18 0.17 Fourth 215.5 89.6 31.9 0.36 0.35 85.5 0.96 0.94 2016 First $ 161.1 $ 59.6 $ (10.8 ) $ (0.12 ) $ (0.12 ) $ (29.4 ) $ (0.33 ) $ (0.33 ) Second 165.2 64.9 (6.8 ) (0.08 ) (0.08 ) (24.6 ) (0.28 ) (0.28 ) Third 216.5 86.2 21.0 0.24 0.24 (7.6 ) (0.08 ) (0.08 ) Fourth 212.9 85.2 16.4 0.18 0.18 19.3 0.21 0.22

Summary of Significant Accoun44

Summary of Significant Accounting Policies (Details) $ in Millions	Jul. 07, 2016USD ($)	Dec. 31, 2017reporting_unit	Sep. 30, 2017reporting_unit	Dec. 31, 2017	Dec. 31, 2017segment	Dec. 31, 2017USD ($)	Dec. 31, 2017segments	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2015USD ($)
Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses						$ 123.1		$ 40.6	$ 0
Goodwill and Intangible Assets [Abstract]
Number of Reporting Units | reporting_unit		3	4
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)						0
Property, Plant and Equipment [Abstract]
Total impairment charges						19.9		0.2	2.3
Revenue Recognition [Abstract]
Sales Discounts, Goods						9.1		8.7	9
Sales Returns and Allowances, Goods						8.5		5.1	6.7
Number of reportable segments					2		2
Noncash Investing and Financing Items [Abstract]
Purchases of property and equipment included in accounts payable						$ 8.5		1.5	2.1
Capital lease obligation										$ 13.6
Maximum
Goodwill and Intangible Assets [Abstract]
Finite-Lived Intangible Asset, Useful Life				15 years
Minimum
Goodwill and Intangible Assets [Abstract]
Finite-Lived Intangible Asset, Useful Life				5 years
Percentage of fair value in excess of carrying amount		40.00%		40.00%	40.00%	40.00%	40.00%
Buildings and improvements | Maximum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				31 years 6 months
Buildings and improvements | Minimum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				5 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				7 years
Machinery and equipment | Minimum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				1 year 6 months
Furniture and fixtures | Maximum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				7 years
Furniture and fixtures | Minimum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				3 years
Vehicles
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				3 years
Software and software development costs | Maximum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				7 years
Software and software development costs | Minimum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life				3 years
Speaker and Receiver Product Line | Discontinued Operations, Disposed of by Sale [Member]
Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses	$ 40.6
Property, Plant and Equipment [Abstract]
Total impairment charges									191.5
Other asset impairment charges									4.1
Patents
Goodwill and Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Period Increase (Decrease)						$ 0			0.5
Patents | Maximum
Goodwill and Intangible Assets [Abstract]
Finite-Lived Intangible Asset, Useful Life				10 years
Patents | Minimum
Goodwill and Intangible Assets [Abstract]
Finite-Lived Intangible Asset, Useful Life				7 years
Impairment of Fixed and Other Assets
Property, Plant and Equipment [Abstract]
Total impairment charges									5.6
Precision Devices
Property, Plant and Equipment [Abstract]
Total impairment charges									2.1
Precision Devices | Timing Device Business [Member] | Discontinued Operations, Disposed of by Sale [Member]
Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses						133.3
Audio
Property, Plant and Equipment [Abstract]
Total impairment charges						21.3		0.5	$ 3.5
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-16 [Member] | Accumulated Deficit
Revenue Recognition [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption								$ (0.1)
Prepaid Expenses and Other Current Assets [Member] | Precision Devices | Timing Device Business [Member]
Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses						$ 10

Disposed and Discontinued Ope45

Disposed and Discontinued Operations (Details) - USD ($) $ in Millions	Jul. 07, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 28, 2017	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from the sale of business		$ 123.1	$ 40.6	$ 0
Gain (Loss) on Disposition of Business		(62.3)	25.6	0
Impairment of intangible assets		16.2
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents		0	2.8	2		$ 2.5
Disposal Group, Including Discontinued Operation, Assets		1.7	80.1
Disposal Group, Including Discontinued Operation, Liabilities		5.6	23.7
Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue		92.2	156.4	331
Disposal Group, Including Discontinued Operation, Costs of Goods Sold		61.5	136.1	319.3
Disposal Group, Including Discontinued Operation, Impairment of Long-Lived Assets		0.4	0.4	50.1
Disposal Group, Including Discontinued Operation, Cost of Goods Sold, Restructuring Charges		0.1	8.9	0.9
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)		30.2	11	(39.3)
Disposal Group, Including Discontinued Operation, Research and Development Expense		7.7	15.1	25.7
Disposal Group, Including Discontinued Operation, General and Administrative Expense		18.5	26.9	58.3
Disposal Group, Including Discontinued Operation, Impairment of Intangible Assets, Finite-lived		0	0	143.3
Disposal Group, Including Discontinued Operation, Restructuring Charges		0.2	3.4	3.5
Disposal Group, Including Discontinued Operation, Operating Expense		26.4	45.4	230.8
Disposal Group, Including Discontinued Operation, Other Expense		1.3
Disposal Group, Including Discontinued Operation, Other Income			(0.9)	(0.6)
Gain (Loss) on Disposition of Business		(62.3)	25.6	0
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax		64.8	(59.1)	(269.5)
Discontinued Operation, Tax Effect of Discontinued Operation		3	3	(18.3)
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax		61.8	(62.1)	(251.2)
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents		0	2.8
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net		1.2	19.2
Disposal Group, Including Discontinued Operation, Inventory, Current		0	17.4
Disposal Group, Including Discontinued Operation, Prepaid and Other Assets, Current		0.5	0.6
Disposal Group, Including Discontinued Operation, Assets, Current		1.7	40
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Noncurrent		0	13.3
Disposal Group, Including Discontinued Operation, Goodwill, Noncurrent		0	23
Disposal Group, Including Discontinued Operation, Intangible Assets, Noncurrent		0	3.7
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent		0	0.1
Disposal Group, Including Discontinued Operation, Assets		1.7	80.1
Disposal Group, Including Discontinued Operation, Accounts Payable, Current		0.1	9.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		5.5	13.6
Disposal Group, Including Discontinued Operation, Liabilities, Current		5.6	22.7
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Noncurrent		0	0.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent		0	0.9
Disposal Group, Including Discontinued Operation, Liabilities		5.6	23.7
Depreciation, Discontinued Operations		2.3	3.3	39.4
Amortization of intangible Assets, Discontinued Operations		1.2	1.4	23.9
Capital Expenditure, Discontinued Operations		2.1	6.5	26.3
Timing Device Business [Member] | Precision Devices | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax		0.4
Proceeds from the sale of business		133.3
Disposal Group, Including Discontinued Operation, Consideration					$ 130
Speaker and Receiver Product Line | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax			26.9
Proceeds from the sale of business	$ 40.6
Disposal Group, Including Discontinued Operation, Consideration	$ 45
Gain (Loss) on Disposition of Business			25.6
Impairment of intangible assets				143.3
Impairment of Long-Lived Assets to be Disposed of				48.2
Other asset impairment charges				4.1
Speaker and Receiver Product Line | Discontinued Operations, Disposed of by Sale [Member] | Impairment of Fixed and Other Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of				50.1
Speaker and Receiver Product Line | Discontinued Operations, Disposed of by Sale [Member] | Research and Development Expense [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of				2.2
Prepaid Expenses and Other Current Assets [Member] | Timing Device Business [Member] | Precision Devices
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from the sale of business		10
Accounts Payable [Member] | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capital Expenditure, Discontinued Operations		$ 0	$ 0.1	$ 1.6

Acquisition Acquisition (Detail

Acquisition Acquisition (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 11, 2017	Jul. 01, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2019
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross														$ 61.6
Revenues			$ 215.5	$ 196	$ 164.4	$ 168.3	$ 212.9	$ 216.5	$ 165.2	$ 161.1		$ 744.2	$ 755.7	753.6
Net earnings (loss)			$ 85.5	$ 15.7	$ (29.7)	$ (3.2)	$ 19.3	$ (7.6)	$ (24.6)	$ (29.4)		68.3	$ (42.3)	$ (233.8)
17Q1 Capacitor Acquisition [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 3.7											$ 2.5
Audience, Inc.
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 61.6
Cash equivalent price (usd per share)		$ 2.51
Consideration transfer, number of shares for each share of acquired entity's shares (in shares)		0.13207
Number of shares issued (in shares)		3,200,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Number of Shares for Unvested Equity Awards Assumed		461,371
Consideration transferred, enterprise value, net of cash and short-term investments		$ 92.8
Cash and short-term investments		30.5
Revenues											$ 19
Net earnings (loss)											$ 31.6
Fair value of total consideration		$ 123.3
Scenario, Forecast [Member] | 17Q1 Capacitor Acquisition [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross															$ 1.2

Acquisition Acquisition - Sched

Acquisition Acquisition - Schedule of Purchase Consideration and Net Asset Allocation (Details) - USD ($) $ in Millions	Jan. 11, 2017	Jul. 01, 2015	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2019
Consideration Transferred [Abstract]
Cash consideration paid to Audience shareholders and equity award holders				$ 61.6
17Q1 Capacitor Acquisition [Member]
Consideration Transferred [Abstract]
Cash consideration paid to Audience shareholders and equity award holders	$ 3.7		$ 2.5
Audience, Inc.
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Number of Shares for Unvested Equity Awards Assumed		461,371
Consideration transferred, enterprise value, net of cash and short-term investments		$ 92.8
Consideration Transferred [Abstract]
Cash consideration paid to Audience shareholders and equity award holders		61.6
Fair value of shares of Knowles common stock issued to Audience shareholders and equity award holders		60.2
Fair value of restricted stock units assumed		1.5
Fair value of total consideration		$ 123.3
Scenario, Forecast [Member] | 17Q1 Capacitor Acquisition [Member]
Consideration Transferred [Abstract]
Cash consideration paid to Audience shareholders and equity award holders					$ 1.2

Acquisition Acquisition - Selec

Acquisition Acquisition - Selected Unaudited Pro-forma Combined Statement of Earnings (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information [Abstract]
Revenues	$ 215.5	$ 196	$ 164.4	$ 168.3	$ 212.9	$ 216.5	$ 165.2	$ 161.1		$ 744.2	$ 755.7	$ 753.6
Earnings (Loss)	$ 31.9	$ 10.5	$ (30.9)	$ (5)	$ 16.4	$ 21	$ (6.8)	$ (10.8)		$ 6.5	$ 19.8	$ 17.4
Per Share - Basic	$ 0.36	$ 0.12	$ (0.35)	$ (0.06)	$ 0.18	$ 0.24	$ (0.08)	$ (0.12)		$ 0.07	$ 0.22	$ 0.20
Per Share - Diluted	$ 0.35	$ 0.12	$ (0.35)	$ (0.06)	$ 0.18	$ 0.24	$ (0.08)	$ (0.12)		$ 0.07	$ 0.22	$ 0.20
Audience, Inc.
Business Acquisition, Pro Forma Information [Abstract]
Revenues									$ 19
Pro-forma											$ 783.6
Pro-forma											$ (36.5)
Pro-forma											$ (0.41)
Pro-forma											$ (0.41)

Impairments (Details)

Impairments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impairment charges on fixed and other assets	$ 5.5	$ 0.9	$ 56.5
Impairment of intangible assets	16.2
Total impairment charges	19.9	0.2	2.3
Impairment of Fixed and Other Assets
Impairment charges on fixed and other assets	5.1	0.5	4.2
Total impairment charges			5.6
Cost of goods
Total impairment charges	1.4	0.3	3.3
Operating Expense
Impairment of intangible assets			1.4
Total impairment charges	19.9	0.2	0.9
Audio
Total impairment charges	$ 21.3	$ 0.5	3.5
Precision Devices
Total impairment charges			$ 2.1

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory, Net [Abstract]
Raw materials	$ 65.9	$ 51.1
Work in progress	21.3	13.3
Finished goods	60.8	51
Subtotal	148	115.4
Less reserves	(22.4)	(24.6)
Total	$ 125.6	$ 90.8

Property, Plant and Equipment51

Property, Plant and Equipment, net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 552	$ 483.9
Less Accumulated depreciation	(369)	(311)
Property, plant and equipment, net	183	172.9
Depreciation	46.5	50.8	$ 54.2
Impairment of Long-Lived Assets Held-for-use	5.5	0.9	56.5
Land
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	7.7	7.7
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	103.2	93.7
Machinery, equipment, and other
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	441.1	382.5
Impairment of Fixed and Other Assets
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 5.1	$ 0.5	$ 4.2

Goodwill and Other Intangible52

Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning balance	$ 871.6	$ 884.2
Acquisitions		0.2
Foreign currency translation	13.3	(12.8)
Ending balance	884.9	871.6
Audio
Goodwill [Roll Forward]
Beginning balance	846.6	859.2
Acquisitions		0.2
Foreign currency translation	13.3	(12.8)
Ending balance	859.9	846.6
Precision Devices
Goodwill [Roll Forward]
Beginning balance	25	25
Acquisitions		0
Foreign currency translation	0	0
Ending balance	$ 25	$ 25

Goodwill and Other Intangible53

Goodwill and Other Intangible Assets - Intangible Assets and Amortization Expense (Details) - USD ($) $ in Millions	Jan. 11, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		$ 46.8	$ 69.3
Accumulated Amortization		25.3	27.5
Intangible Assets, Net		53.5	73.8
Impairment of intangible assets		16.2
Selling and Administrative Expenses
Finite-Lived Intangible Assets [Line Items]
Amortization Expense		7.3	18.2	$ 18.2
Trademarks
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		0.3	0.3
Accumulated Amortization		0.2	0.2
Patents
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		40.8	40.8
Accumulated Amortization		22.2	17.5
Customer relationships (1)
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		3.3	0
Accumulated Amortization		0.7	0
Write off of fully amortized intangibles		137
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 3.3
Finite-Lived Intangible Asset, Useful Life	5 years
Unpatented technologies (1) (2)
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		2.4	28.2
Accumulated Amortization		2.2	9.8
Write off of fully amortized intangibles			53.1
Other (1)
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross		0	0
Accumulated Amortization		0	0
Write off of fully amortized intangibles				$ 3.1
Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		$ 32	$ 32

Goodwill and Other Intangible54

Goodwill and Other Intangible Assets - Indefinite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trademarks
Unamortized intangible assets:
Gross Carrying Amount	$ 32	$ 32

Goodwill and Other Intangible55

Goodwill and Other Intangible Assets - Future Amortization Expense (Details) $ in Millions	Dec. 31, 2017USD ($)
Future Amortization Expense [Abstract]
2,018	$ 5.5
2,019	5.4
2,020	5.3
2,021	5.3
2,022	$ 0

Accrued Expenses and Other Li56

Accrued Expenses and Other Liabilities - Schedule of Accrued Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities and Other Liabilities [Abstract]
Restructuring and exit costs	$ 4.8	$ 2.6
Sales volume rebates	4.7	3.2
Warranty	2.5	2.4
Accrued taxes other than income taxes	2.4	2.1
Warranty	2.1	1
Accrued Insurance	1.9	1.6
Hedging liability	0	3.6
Other	9.8	5.9
Other accrued expenses	$ 28.2	$ 22.4

Accrued Expenses and Other Li57

Accrued Expenses and Other Liabilities - Schedule of Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities and Other Liabilities [Abstract]
Transition tax liability	$ 25.9	$ 0
Deferred compensation, including defined benefit plans	18.7	18.7
Long-term capital leases	12.3	13.2
Unrecognized tax benefits	6.5	4.9
Restructuring and exit costs	0.3	0.2
Other	4.2	3.6
Total	$ 67.9	$ 40.6

Accrued Expenses and Other Li58

Accrued Expenses and Other Liabilities Accrued Expenses and Other Liabilities - Product Warrant Accrual Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Warranty Accrual [Roll Forward]
Beginning balance, January 1	$ 1	$ 1
Provision for warranties	2.8	2.5
Settlements made	(1.3)	(2.1)
Other adjustments, including currency translation	(0.4)	(0.4)
Ending balance, December 31	$ 2.1	$ 1

Restructuring and Related Act59

Restructuring and Related Activities - Costs Recognized and Remaining Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 10.2	$ 10.1	$ 14.3
Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6.2	8.6
Cost of Goods Sold, Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4	1.5
Severance Pay and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8.4	7.5	13.4
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1.8	$ 2.6	0.9
Audience, Inc. | Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			9.5
Audience, Inc. | Severance Pay and Benefits | Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			9
Audience, Inc. | Facility Closing [Member] | Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			0.5
2015 Other Restructuring Actions Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			4.8
2015 Other Restructuring Actions Plan [Member] | Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2.1
2015 Other Restructuring Actions Plan [Member] | Cost of Goods Sold, Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2.7
2015 Other Restructuring Actions Plan [Member] | Severance Pay and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			4.4
2015 Other Restructuring Actions Plan [Member] | Contract Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 0.4

Restructuring and Related Act60

Restructuring and Related Activities - Restructuring Activities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 10.2	$ 10.1	$ 14.3
Restructuring Reserve, Accrual Adjustment	1.2
Restructuring Reserve [Roll Forward]
Beginning balance	2.8	8.8	6.9
Restructuring charges	10.2	10.1	14.3
Payments	(8.3)	(16.1)	(11.9)
Other, including foreign currency	0.4		(0.5)
Ending balance	5.1	2.8	8.8
Severance Pay and Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	2.4	7.7	6.4
Restructuring charges	8.4	7.5	13.4
Payments	(6.5)	(12.8)	(11.7)
Other, including foreign currency	0.4		(0.4)
Ending balance	4.7	2.4	7.7
Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Beginning balance	0.4	1.1	0.5
Restructuring charges	1.8	2.6	0.9
Payments	(1.8)	(3.3)	(0.2)
Other, including foreign currency	0		(0.1)
Ending balance	0.4	0.4	1.1
Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	2	1.6	0.6
Audio
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	8.1	7.1	13.4
Precision Devices
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.1	1.4	0.3
Restructuring Charges [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	6.2	8.6
Cost of Goods Sold, Restructuring Charges [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	$ 4	$ 1.5
2015 Other Restructuring Actions Plan [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges			4.8
2015 Other Restructuring Actions Plan [Member] | Severance Pay and Benefits
Restructuring Reserve [Roll Forward]
Restructuring charges			4.4
2015 Other Restructuring Actions Plan [Member] | Restructuring Charges [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges			2.1
2015 Other Restructuring Actions Plan [Member] | Cost of Goods Sold, Restructuring Charges [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges			$ 2.7

Restructuring and Related Act61

Restructuring and Related Activities - Balance Sheet Location (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 5.1	$ 2.8	$ 8.8	$ 6.9
Other accrued expenses
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	4.8	2.6
Other liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 0.3	$ 0.2

Hedging Transactions and Deri62

Hedging Transactions and Derivative Instruments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 14, 2017	Nov. 12, 2014
Derivative [Line Items]
Unrealized net gains (losses) arising during period	$ 3.4	$ (2.5)	$ (1.4)
Not Designated as Hedging Instrument, Economic Hedge [Member] | Foreign Currency Economic Hedge | Not Designated as Hedging Instrument | Other expense (income), net
Derivative [Line Items]
Gain (loss) on derivatives	(0.3)	(2)	0.3
Cash Flow Hedging | Designated as Hedging Instrument | Other expense (income), net
Derivative [Line Items]
Gain (loss) on derivatives	(0.5)	(1)	$ 0
Cash Flow Hedging | Foreign Exchange Forward and Interest Rate Swap [Member] | Designated as Hedging Instrument
Derivative [Line Items]
Unrealized net gains (losses) arising during period	0.5	3.2
Cash Flow Hedging | Foreign Exchange Forward | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	$ 17.9	$ 75.4
Cash Flow Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount				$ 50	$ 100

Hedging Transactions and Deri63

Hedging Transactions and Derivative Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Fair value	$ 0	$ 3.6
Unrealized net gains (losses) arising during period	3.4	(2.5)	$ (1.4)
Cash Flow Hedging | Designated as Hedging Instrument | Foreign Exchange Forward and Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Unrealized net gains (losses) arising during period	0.5	3.2
Cash Flow Hedging | Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value	0.6	0
Cash Flow Hedging | Designated as Hedging Instrument | Other accrued expenses
Derivatives, Fair Value [Line Items]
Fair value	0	3.6
Cash Flow Hedging | Designated as Hedging Instrument | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value	0	0.2
Not Designated as Hedging Instrument, Economic Hedge [Member] | Not Designated as Hedging Instrument | Foreign Currency Gain (Loss) [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 6.4	$ 0

Hedging Transaction and Derivat

Hedging Transaction and Derivative Instruments - Fair Value of Derivatives Qualifying as Hedging Instrument (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gains (losses) arising during period	$ 3.4	$ (2.5)	$ (1.4)
Designated as Hedging Instrument | Cash Flow Hedging | Other expense (income), net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	0.5	1	0
Foreign Currency Economic Hedge | Not Designated as Hedging Instrument | Not Designated as Hedging Instrument, Economic Hedge [Member] | Other expense (income), net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	0.3	2	$ (0.3)
Foreign Exchange Forward and Interest Rate Swap [Member] | Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gains (losses) arising during period	$ 0.5	$ 3.2

Borrowings and Lines of Credi65

Borrowings and Lines of Credit - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	May 04, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 0
Long-term Debt, Maturities, Repayments of Principal in Year Two	0
Long-term Debt, Maturities, Repayments of Principal in Year Three	0
Long-term borrowings [Abstract]
Long-term debt	192.6	$ 298.2
Less: current maturities	0	9.7
Long-term debt (noncurrent)	192.6	288.5
Term Loan and Revolving Credit Facility Due January 2019 [Member]
Long-term borrowings [Abstract]
Long-term debt	50.7	163.1
Less: current maturities	0	10.6
Long-term debt (noncurrent)	$ 50.7	152.5
Convertible Debt | Convertible Notes Due Twenty Twenty One [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	17250000000.00%		3.25%
Long-term Debt, Maturities, Repayments of Principal in Year Four	$ 172.5
Long-term borrowings [Abstract]
Convertible Debt	141.9	135.1
Line of Credit | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Year Five	50.7
Long-term borrowings [Abstract]
Long-term Line of Credit	$ 50.7
Line of Credit | Term Loan and Revolving Credit Facility Due January 2019 [Member]
Long-term borrowings [Abstract]
Long-term Line of Credit		$ 163.1

Borrowings and Lines of Credi66

Borrowings and Lines of Credit - Schedule of Interest Expense and Interest Income (Details) - USD ($) $ in Millions	Feb. 09, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Interest expense(1)		$ 20.8	$ 20.5	$ 12.8
Interest income		(0.2)	(0.1)	(0.1)
Interest Revenue (Expense), Net		(20.6)	(20.4)	$ (12.7)
Write off of Deferred Debt Issuance Cost	$ 0.7	0.4
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Year Two		0
Long-term Debt, Maturities, Repayments of Principal in Year Three		0
Convertible Debt | Convertible Notes Due Twenty Twenty One [Member]
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization		5.6	3.7
Interest Expense, Debt		12.3	$ 7.9
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Year Four		$ 172.5

Borrowings and Lines of Credi67

Borrowings and Lines of Credit Borrowings and Lines of Credit - Narrative (Details)	Oct. 11, 2017USD ($)	Jan. 27, 2014USD ($)	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / shares	May 04, 2016$ / shares	Feb. 09, 2016USD ($)	Feb. 08, 2016USD ($)	Dec. 30, 2014USD ($)
Debt Instrument [Line Items]
Long-term debt			$ 192,600,000	$ 298,200,000
Long-term Debt, Current Maturities			$ 0	$ 9,700,000
Debt Instrument, Convertible, Conversion Ratio			54.2741
Debt Instrument, Convertible, Conversion Price | $ / shares			$ 18.4250
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share | $ / shares			$ 0.69	$ (0.70)	$ (2.89)
Long-term debt			$ 192,600,000	$ 288,500,000
Net deferred tax asset			$ 22,400,000
Document Fiscal Year Focus			2,017
Payments for Hedge, Financing Activities			$ 0	44,500,000	$ 0
Proceeds from issuance of warrants			$ 0	39,100,000	0
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 200,000,000			350,000,000				$ 200,000,000
Debt term (in years)		5 years
Line of Credit Facility, Additional Incremental Borrowing Capacity					100,000,000				250,000,000
Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					50,000,000				$ 25,000,000
Bridge Loan | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					$ 35,000,000
Convertible Notes Due Twenty Twenty One [Member] | Convertible Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			17250000000.00%			3.25%
Debt instrument, face amount			$ 172,500,000	172,500,000
Debt instrument, convertible, carrying amount of equity component			29,900,000	29,900,000
Debt Issuance Costs Attributable to the Equity Component			1,300,000
Interest Expense, Debt, Excluding Amortization			5,600,000	3,700,000
Amortization of Debt Issuance Costs			900,000	600,000
Amortization of Debt Discount (Premium)			5,800,000	3,600,000
Debt Issuance Costs, Net			5,000,000
Net deferred tax asset			500,000
Debt Instrument, Unamortized Discount			(30,600,000)	(37,400,000)
Convertible Notes Payable			141,900,000	135,100,000
Convertible Notes Payable, Current			0	(900,000)
Convertible Notes Payable, Noncurrent			141,900,000	136,000,000
Debt Instrument, Fair Value Disclosure			191,400,000
Payments for Hedge, Financing Activities			44,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares						$ 21.1050
Proceeds from issuance of warrants			39,100,000
Interest Expense, Debt			$ 12,300,000	7,900,000
Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Debt covenant, EBITDA to interest ratio			3.25
Debt Instrument, Covenant, Debt to EBITDA, Maximum			3.75
Debt Instrument, Covenant, Senior Secured Leverage Ratio, Maximum			3.25
Line of credit facility, maximum borrowing capacity	$ 400,000,000
Credit Facility Due October 11, 2022 [Member] | Line of Credit
Debt Instrument [Line Items]
Long-term Line of Credit			$ 50,700,000
Credit Facility Due October 11, 2022 [Member] | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 100,000,000
Debt term (in years)	5 years
Credit Facility Due October 11, 2022 [Member] | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Long-term debt			50,700,000	0
Credit Facility Due October 11, 2022 [Member] | Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000,000
Term Loan and Revolving Credit Facility Due January 2019 [Member]
Debt Instrument [Line Items]
Long-term debt			50,700,000	163,100,000
Long-term Debt, Current Maturities			0	10,600,000
Long-term debt			50,700,000	152,500,000
Term Loan and Revolving Credit Facility Due January 2019 [Member] | Line of Credit
Debt Instrument [Line Items]
Long-term Line of Credit				163,100,000
Term Loan Due January 2019 [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net			0	400,000
Term Loan Due January 2019 [Member] | Senior Notes
Debt Instrument [Line Items]
Long-term debt			0	118,500,000
Senior Secured Note Issued January 2014 | Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		$ 300,000,000
Debt term (in years)		5 years
Credit Agreement Amendment February 2016 | Line of Credit
Debt Instrument [Line Items]
Long-term debt							$ 300,000,000
Credit Agreement Amendment February 2016 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity								$ 350,000,000
Revolving Credit Facility due January 2019 [Member] | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Long-term debt			$ 0	$ 45,000,000
London Interbank Offered Rate (LIBOR) | Credit Facilities
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time			3.58%	3.23%
Minimum | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.20%
Minimum | London Interbank Offered Rate (LIBOR) | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.25%
Maximum | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.35%
Maximum | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Line of credit facility, accordion feature, increase limit	$ 200,000,000
Maximum | London Interbank Offered Rate (LIBOR) | Credit Facility Due October 11, 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			2.25%
Weighted Average | Credit Facilities
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.36%	0.39%

Income Taxes - Income before Ta

Income Taxes - Income before Tax, Domestic and Foreign (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Earnings before Income Tax [Abstract]
Domestic	$ 402.7	$ (51.1)	$ (57.9)
Foreign	(383.3)	79.2	78.5
(Loss) earnings before income taxes	$ 19.4	$ 28.1	$ 20.6

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
U.S. Federal	$ 28.9	$ 0	$ 1.9
State and local	0.1	0.1	0
Foreign	11.7	6.8	9.9
Total current tax expense	40.7	6.9	11.8
Deferred:
U.S. Federal	(26.8)	0.8	(3.5)
State and local	0	0.2	(0.1)
Foreign	(1)	0.4	(5)
Total deferred tax (benefit) expense	(27.8)	1.4	(8.6)
Total income tax expense	$ 12.9	$ 8.3	$ 3.2

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation [Abstract]
U.S. Federal income tax rate	35.00%	35.00%	35.00%
State and local taxes, net of Federal income tax benefit	(0.20%)	1.10%	(7.40%)
Foreign operations tax effect	27.00%	(22.50%)	(36.60%)
Research & experimentation tax credits	(11.60%)	(6.60%)	(12.40%)
Valuation allowance	60.80%	69.60%	97.00%
Tax contingencies	6.60%	(0.60%)	(1.30%)
Tax holiday	(78.00%)	(64.20%)	(87.90%)
Foreign taxes	(5.00%)	2.80%	8.80%
Other, principally non-tax deductible items (1)	0.00%	0.00%	5.90%
Stock-based compensation	9.30%	9.60%	4.70%
Other, principally non-tax deductible items (1)	12.70%	5.10%	9.50%
Transition tax	89.70%	0.00%	0.00%
Tax reform	(85.30%)	0.00%	0.00%
Prior period items	5.50%	0.20%	0.20%
Effective income tax rate	66.50%	29.50%	15.50%
Foreign Tax Authority
Effective Income Tax Rate Reconciliation [Abstract]
Tax holiday	(7.20%)
Effective income tax rate reconciliation, tax holiday	$ 13.8	$ 16.3	$ 17.7
Income tax holiday benefit (usd per share)	$ 0.15	$ 0.18	$ 0.20
Inland Revenue, Singapore (IRAS) | Foreign Tax Authority
Effective Income Tax Rate Reconciliation [Abstract]
Foreign statutory income tax rate	24.00%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Line Items]
Deferred tax assets, valuation allowance, judgment regarding the realizability of the beginning of the year deferred tax asset	$ 99.7	$ 161.3
Deferred tax assets:
Accrued compensation, principally post-retirement, and other employee benefits	13.7	19
Accrued expenses, principally for state income taxes, interest, and warranty	5.9	6.5
Net operating loss and other carryforwards	115.6	148.2
Inventories, principally due to reserves for financial reporting purposes and capitalization for tax purposes	3.6	7.5
Convertible Note Hedges	7.3	14.6
Plant and equipment, principally due to differences in depreciation	9.6	4.5
Total gross deferred tax assets	155.7	200.3
Valuation allowance	(99.7)	(161.3)
Total deferred tax assets	56	39
Deferred tax liabilities:
Intangible assets, principally due to different tax and financial reporting bases and amortization lives	(10.3)	(27.3)
Debt discount on convertible notes	(5.7)	(11.6)
Other liabilities	(17.6)	(6.7)
Total gross deferred tax liabilities	(33.6)	(45.6)
Net deferred tax liability		6.6
Classified as follows in the Consolidated Balance Sheets:
Other assets and deferred charges (non-current deferred tax assets)	22.4	15
Deferred income taxes (non-current deferred tax liabilities)	0	(21.6)
Net deferred tax liability		$ 6.6
Net deferred tax asset	$ 22.4

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Abstract]
Deferred tax assets, valuation allowance, judgment regarding the realizability of the beginning of the year deferred tax asset	$ 99.7	$ 161.3
Amount of change in deferred tax assets valuation allowance	11.7
Income Tax Credits [Abstract]
Undistributed earnings of foreign subsidiaries	1,700
State and Local Jurisdiction
Net Operating Loss Carryforwards [Abstract]
Operating loss carryforwards, subject to expiration	96.9
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Subject to Expiration in 1-5 years	3.1
Net Operating Loss Carryforwards [Abstract]
Operating loss carryforwards	314.2
Operating Loss Carryforwards, Subject to Expiration in 5-10 years	0.8
Operating Loss Carryforwards, Not Subject to Expiration	310.3
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Subject to Expiration in 1-5 years	0
Net Operating Loss Carryforwards [Abstract]
Operating loss carryforwards	34.2
Operating Loss Carryforwards, Subject to Expiration in 5-10 years	12.2
Operating Loss Carryforwards, Subject to Expiration in 10-20 years	22
Research Tax Credit Carryforward
Income Tax Credits [Abstract]
Tax credit carryforward amount	7.7
Foreign Tax Credit Carryforward
Income Tax Credits [Abstract]
Tax credit carryforward amount	3.3
State Tax Credit Carryforward
Income Tax Credits [Abstract]
Tax credit carryforward amount	13.8
Tax Year 2019 Through Tax Year 2033 | State Tax Credit Carryforward
Income Tax Credits [Abstract]
Tax credit carryforward amount	1.4
After Tax Year 2033 | State Tax Credit Carryforward
Income Tax Credits [Abstract]
Tax credit carryforward amount	$ 12.4

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Interest expense on income taxes	$ (1.1)	$ 0.3	$ 0
Accrued interest on income taxes	0.4	1.4	1.3
Potential penalty expense	0.2
Total accrued liabilities	0.2
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	(2.8)
Potential benefit on the effective tax rate	6
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits beginning balance	11.8	12.8	5
Reductions for tax positions due to lapsed statutes of limitations			(0.4)
Additions for business combinations			8.4
Foreign exchange fluctuations		(0.5)	(0.2)
Additions based on tax positions related to the current year	2.6
Additions for tax positions of prior years	0.6
Reductions for tax positions due to lapsed statutes of limitations	1.3	0.5
Tax reform	(1.5)
Foreign exchange fluctuations	0.3
Unrecognized tax benefits ending balance	12.5	11.8	$ 12.8
Deferred tax liability, provisional income tax benefit	(5.6)
Amount of change in deferred tax assets valuation allowance	11.7
Provisional tax benefit	(18)
Transition tax liability	25.9	$ 0
Deferred tax asset, provisional income tax expense	$ 7.9

Equity Incentive Program - Shar

Equity Incentive Program - Share Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Pre-tax compensation expense	$ 24.7	$ 20.9	$ 15
Tax benefit	0	0	0
Total stock-based compensation expense, net of tax	24.7	20.9	15
Selling and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Pre-tax compensation expense	16.8	14.7	11.8
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Pre-tax compensation expense	6.1	4.7	2
Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Pre-tax compensation expense	$ 1.8	$ 1.5	$ 1.2

Equity Incentive Program - Stoc

Equity Incentive Program - Stock Options and SSARs (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SSARs, Number of Shares (in shares):
Forfeited	0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Dividend yield	0.00%	0.00%
Expected life (years)	4 years 6 months	4 years 6 months	4 years 6 months
SSARs, Weighted-average grant date fair value (in dollars per share):
Granted	$ 19.02
Stock Options, Number of Shares (in share):
Beginning balance	4,684,117
Granted	832,826
Exercised	(229,028)
Forfeited	(286,907)
Expired	(99,269)
Ending balance	4,901,739	4,684,117
Exercisable	2,224,961
Stock Options, Weighted Average Exercise Price (in dollars per share):
Beginning balance	$ 18.03
Granted	19.02
Exercised	14.33
Forfeited	15.48
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price	24.55
Ending balance	18.36	$ 18.03
Exercisable	$ 20.52
SARS and Options, Additional Disclosures
Options, aggregate intrinsic value, outstanding	$ 5,700
Options, aggregate intrinsic value, exercisable	$ 1,700
Options, weighted average remaining contractual term, outstanding	4 years 8 months
Options, weighted average remaining contractual term, exercisable	4 years 2 months
Unrecognized compensation expense	$ 7,300
Weighted average period for compensation expense to be recognized	1 year 2 months
SSARs and Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Dividend yield			0.00%
SSARs
SSARs, Number of Shares (in shares):
Beginning balance	898,718
Granted	0
Exercised	(31,665)
Expired	(16,537)
Ending balance	850,516	898,718
Exercisable	850,516
SSARs, Weighted-average grant date fair value (in dollars per share):
Beginning balance	$ 21.25
Granted	0
Exercised	12.33
Forfeited	0
Expired	23.20
Ending balance	21.54	$ 21.25
Exercisable	21.54
Stock Options, Weighted Average Exercise Price (in dollars per share):
Granted	$ 0
SARS and Options, Additional Disclosures
SSARs, aggregate intrinsic value, outstanding	$ 100
SSARs, aggregate intrinsic value, exercisable	$ 100
SSARs, weighted average remaining contractual terms, outstanding	4 years
SSARs, weighted average remaining contractual term, exercisable	4 years
Unrecognized compensation expense	$ 0
Minimum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	1.73%	1.04%	1.24%
Volatility	33.20%	37.00%	39.80%
Fair value at date of grant	$ 5.02	$ 3.76	$ 5.94
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	1.93%	1.25%	1.50%
Volatility	38.80%	39.60%	42.40%
Fair value at date of grant	$ 6.73	$ 4.83	$ 6.88

Equity Incentive Program - RSUs

Equity Incentive Program - RSUs (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Stock Options
Weighted Average Grant Date Fair Value (in dollars per share):
Unrecognized compensation expense | $	$ 7.3
Weighted average period for compensation expense to be recognized	1 year 2 months
Restricted Stock Units (RSUs)
Number of Shares (in shares):
Beginning balance | shares	2,074,998
Granted | shares	1,375,335
Vested | shares	(821,620)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period | shares	(426,137)
Ending balance | shares	2,202,576
Weighted Average Grant Date Fair Value (in dollars per share):
Beginning balance | $ / shares	$ 14.94
Granted | $ / shares	18.55
Vested | $ / shares	16.11
Forfeited | $ / shares	15.77
Ending balance | $ / shares	$ 16.54
Unrecognized compensation expense | $	$ 23.1
Weighted average period for compensation expense to be recognized	1 year 4 months 15 days
February 28, award 1 | Share-based Compensation Award, Tranche Two [Member] | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%
February 28, award 1 | Share-based Compensation Award, Tranche Two [Member] | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%
February 28, award 1 | Third Anniversary of Grant Date | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%
February 28, award 1 | Third Anniversary of Grant Date | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%

Equity Incentive Program - Addi

Equity Incentive Program - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2017	Jul. 01, 2015
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	7 years
February 28, award 1 | Third Anniversary of Grant Date | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%
February 28, award 1 | Third Anniversary of Grant Date | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	50.00%
February 28, award 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Audience, Inc.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Number of Shares for Unvested Equity Awards Assumed		461,371

Equity Incentive Program Equity

Equity Incentive Program Equity Incentive Program - Other Information Regarding SSARs and Stock Options (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Fiscal Year Focus	2,017
Cash received by Knowles for exercise of stock options	$ 3.3	$ 0	$ 0
SSARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of SSARs that are exercisable	1.9	1.9	0.6
Aggregate intrinsic value of SSARs exercised	0.2	0.1	0.1
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash received by Knowles for exercise of stock options	3.3	0	0
Aggregate intrinsic value of options exercised	$ 1.1	$ 0	$ 0

Equity Incentive Program Equi79

Equity Incentive Program Equity Incentive Program - PSUs (Details) - Performance Shares [Member] - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2017	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		176,000	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		176,000
Vested		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 15.32	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		15.32
Vested		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 0
Unrecognized compensation expense		$ 2
Weighted average period for compensation expense to be recognized		2 years 1 month
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Incremental Increase of Initial Grant Value, Percentage	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Incremental Increase of Initial Grant Value, Percentage	225.00%

Commitments and Contingent Li80

Commitments and Contingent Liabilities - Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rent expense net of sublease rental income	$ 6.8	$ 7.8	$ 10.2
Operating Leases, Rent Expense, Sublease Rentals	2.2	$ 1.3	$ 0
Capital Leases [Abstract]
2,018	2.4
2,019	2.4
2,020	2.4
2,021	2.4
2,022	2.4
2023 and thereafter	5.3
Total minimum lease payments	17.3
Capital Leases, Future Minimum Sublease Rentals	0
Capital Leases, Future Minimum Payments, Net Minimum Payments	17.3
Capital Leases, Future Minimum Payments, Interest Included in Payments	(2.5)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	14.8
Operating Lease Future Minimum Payments [Abstract]
2,018	9.2
2,019	8.8
2,020	8.2
2,021	8
2,022	7.2
2023 and thereafter	18.5
Total minimum lease payments	59.9
Future operating lease payments	59.9
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	(10.5)
Operating Leases, Future Minimum Payments, Net Minimum Payments	$ 49.4

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)pension_plan	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expense	$ 6.4	$ 6.1	$ 5
Number of defined benefit pension plans | pension_plan	3
Actuarial losses arising during period, net of tax	$ (0.7)	5.6	0.6
Non-Qualified Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Actuarial losses arising during period, before tax	0.1
Actuarial losses arising during period, net of tax	0.1
Amortization of recognized actuarial loss	0.1
Amortization of gains (losses), net of tax	0.1
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected future amortization of gain (loss)	0.5
Amortization of recognized actuarial loss	$ 0.5	$ 0.3	$ 0.4

Employee Benefit Plans - Change

Employee Benefit Plans - Change in Benefit Obligation and Funded Status (Details) - Foreign Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 52.4	$ 51
Service cost	0.3	0.2	$ 0.2
Interest cost	1.5	1.6	2
Defined Benefit Plan, Benefit Obligation, Benefits Paid	1.5	1.7
Actuarial loss	0.5	10.1
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	0.3	0
Settlements and curtailments	0	(0.2)
Currency translation and other	4.4	(8.6)
Benefit obligation at end of year	57.9	52.4	51
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	43.8	45.1
Actual return on plan assets	4.4	6.7
Company contributions	1.5	1.7
Defined Benefit Plan, Plan Assets, Benefits Paid	1.5	1.7
Settlements and curtailments	0	(0.2)
Currency translation and other	3.6	(7.8)
Fair value of plan assets at end of year	51.8	43.8	$ 45.1
Funded status	(6.1)	(8.6)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Other assets and deferred charges	0.4	0
Other liabilities	(6.5)	(8.6)
Funded status	(6.1)	(8.6)
Accumulated Other Comprehensive Loss (Earnings) [Abstract]
Net actuarial losses	18.4	20.1
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax	0.3	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), Tax	(3.6)	(3.6)
Total Accumulated Other Comprehensive Loss, net of tax	15.1	16.5
Amounts recognized on the balance sheet including accumulated other comprehensive income (loss)	9	7.9
Accumulated benefit obligation	$ 57	$ 51.3

Employee Benefit Plans - Accumu

Employee Benefit Plans - Accumulated Benefit Obligations in Excess of Plan Assets (Details) - Foreign Plan [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets [Abstract]
Projected benefit obligation	$ 35.3	$ 32.6
Accumulated benefit obligation	34.8	31.9
Fair value of plan assets	$ 28.8	$ 24.2

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of the Net Periodic Benefit Cost (Details) - Foreign Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 0.3	$ 0.2	$ 0.2
Interest cost	1.5	1.6	2
Expected return on plan assets	(2.7)	(2.4)	(2.9)
Amortization of recognized actuarial loss	0.5	0.3	0.4
Settlement and curtailment loss	0	0	0.1
Total net periodic benefit income	$ (0.4)	$ (0.3)	$ (0.2)

Employee Benefit Plans - Actuar

Employee Benefit Plans - Actuarial Assumptions (Details) - Foreign Plan [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	2.40%	2.60%
Average wage increase	4.46%	4.55%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	2.60%	3.72%	3.66%
Average wage increase	4.55%	4.16%	4.23%
Expected return on plan assets	5.80%	6.42%	6.38%
Taiwan
Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	1.25%	1.50%
Average wage increase	4.00%	4.00%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	1.50%	1.10%	2.00%
Average wage increase	4.00%	4.00%	4.00%
Expected return on plan assets	1.75%	1.50%	1.50%
United Kingdom
Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	2.44%	2.65%
Average wage increase	4.50%	4.60%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	2.64%	3.90%	3.75%
Average wage increase	4.60%	4.25%	4.25%
Expected return on plan assets	5.90%	6.50%	6.53%

Employee Benefit Plans - Fair V

Employee Benefit Plans - Fair Value of Plan Assets by Category (Details) - Foreign Plan [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 51.8	$ 43.8	$ 45.1
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9.2	7.8
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42.6	36
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	13
Fixed income investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.3	2.5
Fixed income investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.7	10.5
Fixed income investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common stock funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21.9	18.7
Common stock funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common stock funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21.9	18.7
Common stock funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.5	0
Real Estate Funds [Member] | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Real Estate Funds [Member] | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.5	0
Real Estate Funds [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	3.5
Cash and equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.1	0.2
Cash and equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.9	3.3
Cash and equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.4	8.6
Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.8	5.1
Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.6	3.5
Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

Employee Benefit Plans - Future

Employee Benefit Plans - Future Estimates (Details) - Foreign Plan [Member] $ in Millions	Dec. 31, 2017USD ($)
Expected Future Benefit Payments [Abstract]
2,018	$ 1.7
2,019	1.6
2,020	1.7
2,021	1.7
2,022	1.8
2023 - 2027	10.9
Estimated Future Employer Contributions [Abstract]
Estimated 2018 employer contribution	$ 1.8

Employee Benefit Plans - Supple

Employee Benefit Plans - Supplemental Retirement Plan (Details) - Non-Qualified Supplemental Retirement Plan $ in Millions	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Other liabilities	$ (0.2)
Pension and Other Postretirement Defined Benefit Plans, Other LIabilities	(1.6)
Total Accumulated Other Comprehensive Loss, net of tax	0.2
Amounts recognized on the balance sheet including accumulated other comprehensive income (loss)	$ (1.6)

Other Comprehensive (Loss) Ea89

Other Comprehensive (Loss) Earnings - Amounts Recognized in OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign currency translation:
Foreign currency translation, before tax	$ 27.1	$ 0.8	$ (71.7)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Parent	0	0	0
Foreign currency translation, net of tax	27.1	0.8	(71.7)
Employee benefit plans:
Employee benefit plans, before Tax	1.3	(5)	0.2
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent	0	(0.1)	0
Net change in employee benefit plans	1.3	(5.1)	0.2
Changes in fair value of cash flow hedges:
Change in fair value of cash flow hedges, before tax	4.4	(2.2)	(1.4)
Change in fair value of cash flow hedges, tax	(0.7)	0.6	0
Total cash flow hedges	3.7	(1.6)	(1.4)
Total:
Other Comprehensive Income (Loss), before tax	32.8	(6.4)	(72.9)
Other Comprehensive Income (Loss), tax	(0.7)	0.5	0
Other comprehensive earnings (loss), net of tax	$ 32.1	$ (5.9)	$ (72.9)

Other Comprehensive (Loss) Ea90

Other Comprehensive (Loss) Earnings - Componets of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of AOCI [Abstract]
Beginning balance	$ (132.1)	$ (126.2)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	32.1	(5.9)	$ (72.9)
Ending balance	(100)	(132.1)	(126.2)
Cash flow hedges
Components of AOCI [Abstract]
Beginning balance	(3.2)	(1.6)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	3.7	(1.6)
Ending balance	0.5	(3.2)	(1.6)
Employee benefit plans
Components of AOCI [Abstract]
Beginning balance	(16.6)	(11.5)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1.3	(5.1)
Ending balance	(15.3)	(16.6)	(11.5)
Cumulative foreign currency translation adjustments
Components of AOCI [Abstract]
Beginning balance	(112.3)	(113.1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	27.1	0.8
Ending balance	$ (85.2)	$ (112.3)	$ (113.1)

Other Comprehensive (Loss) Ea91

Other Comprehensive (Loss) Earnings - Changes in Components of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Postretirement Benefit Plans [Abstract]
Amortization or settlement of actuarial losses and prior service costs	$ 0.6	$ 0.5	$ 0.8
Tax benefit	0	0	0
Net of tax	0.6	0.5	0.8
Cash Flow Hedges [Abstract]
Net losses reclassified into earnings	0.5	1	0
Tax benefit	(0.2)	(0.1)	0
Net of tax	$ 0.3	$ 0.9	$ 0

Segment Information - Informati

Segment Information - Information on Reportable Segments (Details) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017segment	Dec. 31, 2017USD ($)	Dec. 31, 2017segments	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments										2		2
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues		$ 215.5	$ 196	$ 164.4	$ 168.3	$ 212.9	$ 216.5	$ 165.2	$ 161.1		$ 744.2		$ 755.7	$ 753.6
Reconciliation of Net Earnings from Segments [Abstract]
Interest expense, net											20.6		20.4	12.7
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	[1]										19.4		28.1	20.6
Provision for income taxes											12.9		8.3	3.2
Earnings (Loss)		$ 31.9	$ 10.5	$ (30.9)	$ (5)	$ 16.4	$ 21	$ (6.8)	$ (10.8)		6.5		19.8	17.4
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization											53.8		69	72.4
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses											93.4		92	83.2
Operating segments
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes	[1]										(95.3)		(101.2)	(90.1)
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures											49.5		32.2	36.8
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses											93.4		92	83.2
Operating segments | Audio
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues											637.4		661.9	654.3
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes											(76.1)		(88.8)	(84.7)
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization											45.2		61.4	65.1
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures											43.6		27.8	26.5
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses											89		89.2	79.5
Operating segments | Precision Devices
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues											106.8		93.8	99.3
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes											(19.2)		(12.4)	(5.4)
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization											5.6		4.3	4.6
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures											5.4		3.1	4
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses											4.2		2.7	3.7
Corporate, Non-Segment [Member]
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes											55.3		52.7	56.8
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization											3		3.3	2.7
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures											0.5		1.3	6.3
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses											$ 0.2		$ 0.1	$ 0
[1]	Years Ended December 31,(in millions)2017 2016 2015Revenues: Audio$637.4 $661.9 $654.3Precision Devices106.8 93.8 99.3Total consolidated revenues$744.2 $755.7 $753.6 Earnings from continuing operations before interest and income taxes: Audio$76.1 $88.8 $84.7Precision Devices19.2 12.4 5.4Total segments95.3 101.2 90.1Corporate expense / other55.3 52.7 56.8Interest expense, net20.6 20.4 12.7Earnings before income taxes and discontinued operations19.4 28.1 20.6Provision for income taxes12.9 8.3 3.2Earnings from continuing operations$6.5 $19.8 $17.4 Depreciation and amortization: Audio$45.2 $61.4 $65.1Precision Devices5.6 4.3 4.6Corporate3.0 3.3 2.7Total$53.8 $69.0 $72.4 Capital expenditures: Audio$43.6 $27.8 $26.5Precision Devices5.4 3.1 4.0Corporate0.5 1.3 6.3Total$49.5 $32.2 $36.8 Research and development: Audio$89.0 $89.2 $79.5Precision Devices4.2 2.7 3.7Corporate0.2 0.1 —Total$93.4 $92.0 $83.2

Segment Information - Reportabl

Segment Information - Reportable Segments Adjusted Working Capital and Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 744.2	$ 755.7	$ 753.6
Total assets	1,549.8	1,515
Disposal Group, Including Discontinued Operation, Assets	1.7	80.1
Operating segments | Audio
Segment Reporting Information [Line Items]
Total assets	1,430.9	1,348.5
Operating segments | Precision Devices
Segment Reporting Information [Line Items]
Total assets	103.4	84.1
Intra-segment eliminations
Segment Reporting Information [Line Items]
Total assets	$ 13.8	$ 2.3

Segment Information - Revenue

Segment Information - Revenue by Geographic Location (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 744.2	$ 755.7	$ 753.6
Long-lived assets	183	172.9
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	560.8	578.7	564.9
Long-lived assets	144.9	130.4
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	101.3	93.3	103.1
Long-lived assets	37.2	41.4
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	72.3	75.1	77.1
Long-lived assets	0.9	1.1
Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	4.4	3.1	3.6
Long-lived assets	0	0
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	5.4	5.5	$ 4.9
Long-lived assets	$ 0	$ 0

Segment Information Segment Inf

Segment Information Segment Information - Concentration of Credit Risk (Details) - Customer Concentration Risk [Member] - Sales Revenue, Segment [Member] - customer	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Audio
Concentration Risk [Line Items]
Concentration risk, number of customers	2	2	2
Audio | Customer A
Concentration Risk [Line Items]
Concentration Risk, Percentage	22.00%	23.00%	25.00%
Audio | Customer B
Concentration Risk [Line Items]
Concentration Risk, Percentage	12.00%	13.00%	12.00%
Precision Devices
Concentration Risk [Line Items]
Concentration Risk, Percentage			10.00%
Concentration risk, number of customers		0	0
Precision Devices | Customer C
Concentration Risk [Line Items]
Concentration Risk, Percentage	10.00%

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions		Jul. 01, 2015	Feb. 28, 2014	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Earnings (Loss)				$ 31.9	$ 10.5	$ (30.9)	$ (5)	$ 16.4	$ 21	$ (6.8)	$ (10.8)		$ 6.5	$ 19.8	$ 17.4
Earnings (loss) from discontinued operations, net													61.8	(62.1)	(251.2)
Net earnings (loss)				$ 85.5	$ 15.7	$ (29.7)	$ (3.2)	$ 19.3	$ (7.6)	$ (24.6)	$ (29.4)		$ 68.3	$ (42.3)	$ (233.8)
Basic earnings (loss) per common share:
Per Share - Basic				$ 0.36	$ 0.12	$ (0.35)	$ (0.06)	$ 0.18	$ 0.24	$ (0.08)	$ (0.12)		$ 0.07	$ 0.22	$ 0.20
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share													0.69	(0.70)	(2.89)
Per Share - Basic				0.96	0.18	(0.33)	(0.04)	0.21	(0.08)	(0.28)	(0.33)		$ 0.76	$ (0.48)	$ (2.69)
Basic weighted average shares outstanding (in shares)	[1]												89,329,794	88,667,098	86,802,828
Diluted earnings (loss) per common share:
Per Share - Diluted				0.35	0.12	(0.35)	(0.06)	0.18	0.24	(0.08)	(0.12)		$ 0.07	$ 0.22	$ 0.20
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share													0.68	(0.69)	(2.89)
Per Share - Diluted				$ 0.94	$ 0.17	$ (0.33)	$ (0.04)	$ 0.22	$ (0.08)	$ (0.28)	$ (0.33)		$ 0.75	$ (0.47)	$ (2.69)
Dilutive weighted average shares outstanding (in shares)	[1]												90,490,007	89,182,967	86,992,254
Stock issued during period (in shares)			0.5
Weighted average number of anti-dilutive shares excluded from the calculation (in shares)													3,944,160	5,080,023	3,357,320
Audience, Inc.
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Net earnings (loss)												$ 31.6
Business Combination, Separately Recognized Transactions [Line Items]
Number of shares issued (in shares)		3,200,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Number of Shares for Unvested Equity Awards Assumed		461,371
[1]	Years Ended December 31, 2017 2016 2015Revenues$744.2 $755.7 $753.6Cost of goods sold452.5 458.0 465.8Impairment charges1.4 0.3 3.3Restructuring charges - cost of goods sold4.0 1.5 2.7Gross profit286.3 295.9 281.8Research and development expenses93.4 92.0 83.2Selling and administrative expenses126.3 149.9 149.7Impairment charges19.9 0.2 2.3Restructuring charges6.2 8.6 11.6Operating expenses245.8 250.7 246.8Operating earnings40.5 45.2 35.0Interest expense, net20.6 20.4 12.7Other expense (income), net0.5 (3.3) 1.7Earnings before income taxes and discontinued operations19.4 28.1 20.6Provision for income taxes12.9 8.3 3.2Earnings from continuing operations6.519.8 17.4Earnings (loss) from discontinued operations, net61.8 (62.1) (251.2)Net earnings (loss)$68.3 $(42.3) $(233.8) Earnings per share from continuing operations: Basic$0.07 $0.22 $0.20Diluted$0.07 $0.22 $0.20 Earnings (loss) per share from discontinued operations: Basic$0.69 $(0.70) $(2.89)Diluted$0.68 $(0.69) $(2.89) Net earnings (loss) per share: Basic$0.76 $(0.48) $(2.69)Diluted$0.75 $(0.47) $(2.69) Weighted-average common shares outstanding: Basic89,329,79488,667,098 86,802,828Diluted90,490,00789,182,967 86,992,254

Quarterly Data (Details)

Quarterly Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 215.5	$ 196	$ 164.4	$ 168.3	$ 212.9	$ 216.5	$ 165.2	$ 161.1	$ 744.2	$ 755.7	$ 753.6
Gross Profit	89.6	74.2	63.2	59.3	85.2	86.2	64.9	59.6	286.3	295.9	281.8
Earnings (Loss)	$ 31.9	$ 10.5	$ (30.9)	$ (5)	$ 16.4	$ 21	$ (6.8)	$ (10.8)	$ 6.5	$ 19.8	$ 17.4
Per Share - Basic	$ 0.36	$ 0.12	$ (0.35)	$ (0.06)	$ 0.18	$ 0.24	$ (0.08)	$ (0.12)	$ 0.07	$ 0.22	$ 0.20
Per Share - Diluted	$ 0.35	$ 0.12	$ (0.35)	$ (0.06)	$ 0.18	$ 0.24	$ (0.08)	$ (0.12)	$ 0.07	$ 0.22	$ 0.20
Net earnings (loss)	$ 85.5	$ 15.7	$ (29.7)	$ (3.2)	$ 19.3	$ (7.6)	$ (24.6)	$ (29.4)	$ 68.3	$ (42.3)	$ (233.8)
Per Share - Basic	$ 0.96	$ 0.18	$ (0.33)	$ (0.04)	$ 0.21	$ (0.08)	$ (0.28)	$ (0.33)	$ 0.76	$ (0.48)	$ (2.69)
Per Share - Diluted	$ 0.94	$ 0.17	$ (0.33)	$ (0.04)	$ 0.22	$ (0.08)	$ (0.28)	$ (0.33)	$ 0.75	$ (0.47)	$ (2.69)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Millions	Jan. 19, 2018	Dec. 31, 2015
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross		$ 61.6
Subsequent Event
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross	$ 16

Schedule II - Valuation and Q99

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 1.5	$ 1.5	$ 0.4
Charged to Cost and Expense	0.2	0.1	1.1
Accounts Written off / Reductions	(1)	(0.1)	0
Balance at End of Year	0.7	1.5	1.5
Deferred Tax Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	161.3	127.4	48.9
Additions	0	33.9	78.5
Accounts Written off / Reductions	(61.6)	0	0
Balance at End of Year	$ 99.7	$ 161.3	$ 127.4