Financial Instruments - Narrative (Details)			6 Months Ended	12 Months Ended
	May 04, 2020 USD ($)	May 04, 2020 EUR (€)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2020 EUR (€)	Jan. 01, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net change in allowance for credit losses			$ 17,200,000	$ 9,900,000
Retained earnings			$ 452,247,000	451,725,000
Line of credit facility, cost expressed as a percentage of extended amount			0.025%
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member
Marketable securities			$ 22,396,000	$ 0
Investments [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Marketable securities			$ 22,000,000		€ 20,000,000
Interest rate percentage			0.25%		0.25%
RCF | Amended RCF Through March 2022 | Revolving credit facility
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revolving credit facility, maximum borrowing capacity			$ 392,000,000		€ 350,000,000
RCF | Amended RCF To The End Of March 2022 Through March 2023 | Revolving credit facility
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revolving credit facility, maximum borrowing capacity			329,000,000		294,000,000
RCF | Bank Syndicate RCF | Revolving credit facility
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revolving credit facility, maximum borrowing capacity			$ 235,200,000		€ 210,000,000.0
Proceeds from lines of credit	$ 156,800,000	€ 140,000,000
Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings						$ 3,500,000