Note 7 - Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Deferred income tax assets:
Pension		$ 7,510	$ 9,722
Non-pension post-retirement benefits		12,271	11,712
Other accrued liabilities		22,486	16,477
Receivables		2,544	1,994
Operating lease liabilities		15,068
Net operating loss and charitable contribution carryforwards	[1]	11,333	14,143
Tax credits	[2]	11,432	13,373
Total deferred income tax assets	[3]	82,644	67,421
Valuation allowances		(26,963)	(22,068)
Net deferred income tax assets		55,681	45,353
Deferred income tax liabilities:
Property, plant and equipment		13,213	15,332
Inventories		1,587	1,699
Operating lease right-of-use assets		14,009
Intangibles and other		4,229	4,987
Total deferred income tax liabilities		33,038	22,018
Net deferred income tax asset		$ 22,643	$ 23,335

[1] At December 31, 2019, non-U.S. operating loss carryforwards of $42.0 million expire between 2021 and 2027.

[2] At December 31, 2019, U.S. general business credit carryforwards of $2.2 million expire between 2024 and 2038. U.S. AMT credits of $0.1 million and the foreign credits of $9.1 million do not expire.

[3] In order to fully realize our U.S. deferred tax assets as of December 31, 2019, the Company needs to generate approximately $179.2 million of future taxable income.