Consolidated Statements Of Shareholders' Equity - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Trust for Savings Restoration Plan	Foreign Currency Translation	Gain (Loss) on Derivative Financial Instruments	Pension & Other Post-retirement Benefit Adjust.
Beginning Balance at Dec. 31, 2017	$ 343,780	$ 34,747	$ 487,230	$ (1,528)	$ (86,178)	$ 459	$ (90,950)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,164		18,164
Foreign currency translation adjustment (net of tax of $0)	1,906				1,906
Derivative financial instruments adjustment (net of tax benefit of $144)	(285)					(285)
Amortization of prior service costs and net gains or losses (net of tax of $762)	2,612						2,612
Cash dividends declared ($0.11 per share)	(3,643)		(3,643)
Stock-based compensation expense	612	612
Issued upon exercise of stock options & other	(247)	(247)
Tredegar common stock purchased by trust for savings restoration plan			8	(8)
Ending Balance at Mar. 31, 2018	$ 362,899	$ 35,112	$ 501,759	$ (1,536)	$ (84,272)	$ 174	$ (88,338)