Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Fair value measurements
Cash and cash equivalents	$ 86,800	$ 105,840	$ 136,291
Fair value measured on a recurring basis
Fair value measurements
Cash and cash equivalents	86,800	105,840	136,291
Available for sale securities	250,845	241,407	207,874
Trading securities	84,662	89,736	78,271
Total assets measured at fair value	422,949	437,533	423,861
Fair value measured on a recurring basis \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	400	426	755
Fair value measured on a recurring basis \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	242	124	670
Fair value measured on a recurring basis \| Level 1
Fair value measurements
Cash and cash equivalents	86,800	105,840	136,291
Available for sale securities	1,264	1,282	3,144
Trading securities	69,076	76,196	65,532
Total assets measured at fair value	157,382	183,442	205,637
Fair value measured on a recurring basis \| Level 1 \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	242	124	670
Fair value measured on a recurring basis \| Level 2
Fair value measurements
Available for sale securities	249,581	240,125	204,730
Trading securities	15,586	13,540	12,739
Total assets measured at fair value	265,567	254,091	218,224
Fair value measured on a recurring basis \| Level 2 \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	$ 400	$ 426	$ 755

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Fair value of asset after deduction of liability.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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