Discontinued Operations - Summary of Discontinued Operations included in Condensed Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Non-operating income (expense)
Income (loss) before income taxes		$ 1,062	$ (135)	$ 1,291
Income tax provision (benefit)		(2,519)		(2,511)
Income (loss) from discontinued operations	$ 0	3,581	(135)	3,802
Specialty Papers [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Selling, general and administrative expenses		(2,455)	135	(2,684)
Operating income (loss)		2,455	(135)	2,684
Non-operating income (expense)
Other, net		(1,393)		(1,393)
Income (loss) before income taxes		1,062	(135)	1,291
Income tax provision (benefit)		(2,519)		(2,511)
Income (loss) from discontinued operations		$ 3,581	$ (135)	$ 3,802

Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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+ Details

- Definition

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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+ Details