Debt - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2012 USD ($) tranche
Line of Credit Facility [Line Items]
Long-term debt, gross	$ 255,700,000	$ 258,000,000.0
Less: current portion of long-term debt	2,300,000	2,300,000
Long-term debt, net	252,900,000	255,000,000.0
Number Tranches | tranche				3
Unamortized debt issuance costs remaining	500,000	700,000
Interest expense	9,600,000	9,400,000	$ 9,300,000
Aggregate annual maturities of long-term debt [Abstract]
2021	2,300,000
2022	44,200,000
2023	2,200,000
2024	134,000,000.0
2025	0.0
Thereafter	73,000,000.0
Series A notes, due July 5, 2022 (3.67%)
Line of Credit Facility [Line Items]
Debt instrument, maturity date				Jul. 05, 2022
Series B notes, due July 5, 2024 (3.82%)
Line of Credit Facility [Line Items]
Debt instrument, maturity date				Jul. 05, 2024
Series C notes, due July 5, 2027 (4.02%)
Line of Credit Facility [Line Items]
Debt instrument, maturity date				Jul. 05, 2027
Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	300,000,000.0
Credit available for the issuance of letters of credit	30,000,000.0
Line of credit facility, additional borrowing capacity	350,000,000.0
Debt issuance costs	400,000	1,100,000
Line of credit, noncurrent	0
Line of credit facility, unused commitment level	297,500,000
Term Loan, due December 31, 2024 (1.13%)
Line of Credit Facility [Line Items]
Debt issuance costs	100,000
Debt instrument, face amount		90,000,000.0
Long-term debt, gross	87,700,000	90,000,000.0
Less: current portion of long-term debt	2,300,000
Long-term debt, net	$ 85,400,000
Debt instrument, stated interest rate	1.13%
Senior Notes
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 168,000,000.0
Weighted average of the coupon interest rate				3.87%
Unamortized debt issuance costs remaining	$ 400,000	$ 500,000
Senior Notes | Series A notes, due July 5, 2022 (3.67%)
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 42,000,000.0
Debt instrument, stated interest rate				3.67%
Senior Notes | Series B notes, due July 5, 2024 (3.82%)
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 53,000,000.0
Debt instrument, stated interest rate				3.82%
Senior Notes | Series C notes, due July 5, 2027 (4.02%)
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 73,000,000.0
Debt instrument, stated interest rate				4.02%
Domestic Line of Credit | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Credit facility is available for swing-line loans	30,000,000.0
Foreign Line of Credit | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Credit facility is available for swing-line loans	$ 20,000,000.0
Fed Funds Effective Rate Overnight Index Swap Rate | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	50.00%
London Interbank Offered Rate (LIBOR) | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.00%
London Interbank Offered Rate (LIBOR) | Term Loan, due December 31, 2024 (1.13%)
Line of Credit Facility [Line Items]
Basis spread on variable interest rate		87.50%
Letter of Credit | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Outstanding amount	$ 2,500,000
Minimum | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Ratio of debt to EBITDA	3.5
Minimum | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.00%
Minimum | London Interbank Offered Rate (LIBOR) | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.875%
Maximum | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Ratio of debt to EBITDA	4.0
Maximum | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.375%
Maximum | London Interbank Offered Rate (LIBOR) | Revolving credit facility, due 2024
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.375%