Discontinued Operations (Summary Of Financial Information That Has Been Segregated From Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Discontinued operations:
Net loss from discontinued operations	$ (2,425)	$ 117	$ (1,608)	$ 48,372	$ 44,456	$ 2,743	$ (9,891)
Assets:
Assets held for sale	0				0	118,470
Discontinued Operations, Held-for-sale | Consumer and Industrial Chemistry Technologies
Discontinued operations:
Revenue					11,031	72,344	73,992
Operating expenses					(11,572)	(65,940)	(63,621)
Depreciation and amortization					0	(2,760)	(2,391)
Research and development					(69)	(590)	(515)
Income (loss) from operations					(610)	3,054	7,465
Other income (expense)					35	341	(284)
Loss on sale of businesses					64,160	0	0
Income (loss) before income taxes					63,585	3,395	7,181
Income tax benefit (expense)					(19,129)	(652)	(2,730)
Net loss from discontinued operations					44,456	2,743	$ 4,451
Assets:
Accounts receivable, net	0				0	10,547
Inventories, net	0				0	52,069
Other current assets	0				0	446
Property and equipment, net	0				0	15,899
Goodwill	0				0	19,480
Other intangible assets, net	0				0	20,029
Assets held for sale	0				0	118,470
Liabilities:
Accounts payable	0				0	8,883
Accrued liabilities	0				0	291
Liabilities held for sale	$ 0				0	9,174
Discontinued Operations, Held-for-sale | Drilling Technologies
Discontinued operations:
Revenue					0	11,534
Cost of revenue					0	(7,309)
Selling, general and administrative					0	(6,963)
Research and development					0	(5)
Gain (loss) on disposal of long-lived assets					0	97
Income (loss) from operations					0	(2,646)
Other income (expense)					0	(96)
Loss on sale of businesses					0	(1,600)
Loss on write-down of assets held for sale					0	(6,831)
Income (loss) before income taxes					0	(11,173)
Income tax benefit (expense)					0	4,138
Net loss from discontinued operations					0	(7,035)
Discontinued Operations, Held-for-sale | Production Technologies
Discontinued operations:
Revenue					0	4,002
Cost of revenue					0	(3,236)
Selling, general and administrative					0	(1,759)
Research and development					0	(364)
Gain (loss) on disposal of long-lived assets					0	0
Income (loss) from operations					0	(1,357)
Other income (expense)					0	(52)
Loss on sale of businesses					0	(479)
Loss on write-down of assets held for sale					0	(9,718)
Income (loss) before income taxes					0	(11,606)
Income tax benefit (expense)					0	4,299
Net loss from discontinued operations					$ 0	$ (7,307)