Long-Term Debt and Short-Term Borrowings - Summary of cumulative effect adjustment upon adoption (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jan. 01, 2021	Dec. 31, 2020
Long-term debt	$ 236,611		$ 193,036
Deferred income taxes	22,061		33,429
Capital in excess of par	143,276		153,529
Retained earnings	$ 282,861		$ 331,897
Accounting Standards Update 2020-06 [Member] \| Cumulative effect period of adoption adjustment
Long-term debt		$ 21,393
Deferred income taxes		(5,584)
Capital in excess of par		(16,511)
Retained earnings		702
Accounting Standards Update 2020-06 [Member] \| Balance at January 1, 2021
Long-term debt		214,429
Deferred income taxes		27,845
Capital in excess of par		137,018
Retained earnings		$ 332,599

Amount of excess of issue price over par or stated value of stock and from other transaction involving stock or stockholder. Includes, but is not limited to, additional paid-in capital (APIC) for common and preferred stock.

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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences with jurisdictional netting.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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