Other Income (Expense), Net (Details) - USD ($) $ in Thousands		3 Months Ended					12 Months Ended
		Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrealized gain (loss) on investments under fair value method							$ 30,600	$ 33,800	$ 1,600
Other Nonoperating Income (Expense)							30,459	51,713	2,381
Other income (expense), net							45	796	(89)
kaleo [Member]
Unrealized Gain (Loss) on Investments - kaleo							30,600	33,800	1,600
Unrealized gain (loss) on investments under fair value method	[1]						30,600	33,800	1,600
Flexible Packaging Films [Member]
Businesss Combination Settlement of Escrow Account			$ 11,900				0	11,900	0
Aluminum Extrusions [Member]
Cast House Explosion pretax income/loss		$ 5,100	$ 900	$ 400	$ 700	$ (1,700)	0	5,300	1,900
Alleghany and Bath County, Virginia [Member]
Unrealized gain (loss) on investments under fair value method					$ 1,000		$ (186)	$ 0	$ (1,032)

[1] See Notes 1, 3, 4 and 17 for more information on losses associated with plant shutdowns, asset impairments and restructurings, unusual items, gains or losses from sale of assets, gains or losses on an investment accounted for under the fair value method and other items.