Segment Information - Information on Reportable Segments (Details) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segments	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Document Fiscal Year Focus										2019
Number of reportable segments | segments										2
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues		$ 233.9	$ 235.9	$ 205.2	$ 179.8	$ 223.8	$ 236.2	$ 188.4	$ 178.5	$ 854.8	$ 826.9	$ 744.2
Reconciliation of Net Earnings from Segments [Abstract]
Interest expense, net										14.5	16.0	20.6
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	[1]									66.3	61.1	19.4
(Benefit from) provision for income taxes										16.6	(4.5)	12.9
Earnings (Loss)		$ 21.1	$ 25.4	$ 5.9	$ (2.7)	$ 79.4	$ (17.8)	$ 4.4	$ (0.4)	49.7	65.6	6.5
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization										54.4	52.4	53.8
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses										96.8	100.6	93.4
Operating segments
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes	[1]									(137.7)	(133.2)	(95.3)
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures										41.2	80.1	49.5
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses										96.8	100.6	93.4
Operating segments | Audio
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues										682.8	682.2	637.4
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes										(107.3)	(105.7)	(76.1)
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization										41.3	41.5	45.2
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures										24.0	68.2	43.6
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses										90.8	94.5	89.0
Operating segments | Precision Devices
Reconciliation from Segment Totals to Consolidated [Abstract]
Revenues										172.0	144.7	106.8
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes										(30.4)	(27.5)	(19.2)
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization										9.9	7.8	5.6
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures										16.5	10.8	5.4
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses										5.8	5.8	4.2
Corporate, Non-Segment [Member]
Reconciliation of Net Earnings from Segments [Abstract]
(Loss) earnings before interest and income taxes										56.9	56.1	55.3
Reconciliation of Depreciation and Amortization [Abstract]
Depreciation and amortization										3.2	3.1	3.0
Reconciliation of Capital Expenditures [Abstract]
Capital expenditures										0.7	1.1	0.5
Reconciliation of Research and Development Expense [Abstract]
Research and development expenses										$ 0.2	$ 0.3	$ 0.2

[1]   Years Ended December 31, (in millions) 2019   2018   2017 Revenues:           Audio $ 682.8
  $ 682.2
  $ 637.4
Precision Devices 172.0
  144.7
  106.8
Total revenues $ 854.8
  $ 826.9
  $ 744.2
            Earnings from continuing operations before interest and income taxes:           Audio $ 107.3
  $ 105.7
  $ 76.1
Precision Devices 30.4
  27.5
  19.2
Total segments 137.7
  133.2
  95.3
Corporate expense / other 56.9
  56.1
  55.3
Interest expense, net 14.5
  16.0
  20.6
Earnings before income taxes and discontinued operations 66.3
  61.1
  19.4
Provision for (benefit from) income taxes 16.6
  (4.5 )   12.9
Earnings from continuing operations $ 49.7
  $ 65.6
  $ 6.5
            Depreciation and amortization:           Audio $ 41.3
  $ 41.5
  $ 45.2
Precision Devices 9.9
  7.8
  5.6
Corporate 3.2
  3.1
  3.0
Total $ 54.4
  $ 52.4
  $ 53.8
            Capital expenditures:           Audio $ 24.0
  $ 68.2
  $ 43.6
Precision Devices 16.5
  10.8
  5.4
Corporate 0.7
  1.1
  0.5
Total $ 41.2
  $ 80.1
  $ 49.5
            Research and development:           Audio $ 90.8
  $ 94.5
  $ 89.0
Precision Devices 5.8
  5.8
  4.2
Corporate 0.2
  0.3
  0.2
Total $ 96.8
  $ 100.6
  $ 93.4