Significant Accounting Policies (Details) $ / shares in Units, shares in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020 USD ($) plan	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) plan	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 11, 2020 USD ($)	Jan. 01, 2019 USD ($)	Nov. 06, 2017 USD ($)
Disaggregation of Revenue
Shares authorized for repurchase													$ 75,000,000
Shares repurchased during the period (shares) | shares					760
Weighted average share price of shares repurchased (per share) | $ / shares					$ 25.40
Total purchase price	[1]									$ (19,300,000)
Shares available for repurchase		$ 55,700,000								55,700,000
Sales		$ 312,400,000	$ 273,200,000	$ 289,600,000	$ 301,900,000	$ 321,400,000	$ 338,000,000.0	$ 287,100,000	$ 269,000,000.0	1,177,100,000	$ 1,215,500,000	$ 1,003,900,000
Cost of sales										845,000,000.0	918,000,000.0	744,800,000
Advertising costs										2,700,000	4,000,000.0	3,700,000
Research and development expense										$ 9,100,000	9,200,000	8,700,000
Number of pension plans (plans) | plan		2								2
Right of use assets		$ 29,000,000.0				34,000,000.0				$ 29,000,000.0	34,000,000.0			$ 34,800,000
Operating lease liability		28,700,000				34,100,000				28,700,000	34,100,000			$ 34,800,000
Convertible Notes, due 2024 | Convertible Debt
Disaggregation of Revenue
Principal amount		$ 258,800,000				$ 258,800,000				258,800,000	258,800,000				$ 258,800,000
Shipping
Disaggregation of Revenue
Sales										10,600,000	11,300,000	10,600,000
Cost of sales										$ 15,000,000.0	$ 15,800,000	$ 15,200,000
Minimum
Disaggregation of Revenue
Finite lived intangible asset useful life										2 years
Maximum
Disaggregation of Revenue
Finite lived intangible asset useful life										15 years

[1] Includes $19.3 in shares repurchased through our share repurchase program. Refer to Note 2, “Significant Accounting Policies,” for further information.