Segment and Geographic Area Information (Schedule of Net Sales and Long-Lived Assets by Geographic Area) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net sales	$ 2,725,169	$ 2,786,558	$ 2,698,419
Long-Lived Assets	884,842	839,756
United States
Segment Reporting Information [Line Items]
Net sales	1,067,306	1,095,881	972,954
Long-Lived Assets	533,286	484,265
Singapore [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	216,768	227,287
Europe, Middle East, Africa, India
Segment Reporting Information [Line Items]
Net sales	818,833	786,764	791,744
Asia Pacific
Segment Reporting Information [Line Items]
Net sales	518,478	573,312	582,971
Other foreign
Segment Reporting Information [Line Items]
Net sales	320,552	330,601	$ 350,750
Long-Lived Assets	$ 134,788	$ 128,204

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

NEWMARKET CORP 10-K