Accumulated Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Summary of cumulative net gain (loss) by component, net of tax, within other comprehensive income

Changes in the components of accumulated other comprehensive income, including amounts reclassified out, for 2017, 2016, and 2015, and the balances in accumulated other comprehensive income as of December 31, 2017, 2016, and 2015 are as follows:

	Gains and Losses On Cash Flow Hedges									Pension and Post- Employment Benefits			Foreign Currency Translation
(Thousands)	Foreign Currency			Precious Metals			Total									Total
Balance at December 31, 2014	$	3,578		$	—		$	3,578		$	(81,662	)	$	(4,153	)	$	(82,237	)
Other comprehensive income (loss) before reclassifications	2,995			—			2,995			2,249			(1,335		)	3,909
Amounts reclassified from accumulated other comprehensive income	(6,169		)	—			(6,169		)	5,580			—			(589		)
Other comprehensive income (loss) before tax	(3,174		)	—			(3,174		)	7,829			(1,335		)	3,320
Deferred taxes on current period activity	(1,175		)	—			(1,175		)	2,963			—			1,788
Other comprehensive income (loss) after tax	(1,999		)	—			(1,999		)	4,866			(1,335		)	1,532
Balance at December 31, 2015	$	1,579		$	—		$	1,579		$	(76,796	)	$	(5,488	)	$	(80,705	)
Balance at December 31, 2015	$	1,579		$	—		$	1,579		$	(76,796	)	$	(5,488	)	$	(80,705	)
Other comprehensive income (loss) before reclassifications	(377		)	—			(377		)	(14,165		)	(172		)	(14,714		)
Amounts reclassified from accumulated other comprehensive income	784			—			784			4,048			—			4,832
Other comprehensive income (loss) before tax	407			—			407			(10,117		)	(172		)	(9,882		)
Deferred taxes on current period activity	149			—			149			(4,555		)	—			(4,406		)
Other comprehensive income (loss) after tax	258			—			258			(5,562		)	(172		)	(5,476		)
Balance at December 31, 2016	$	1,837		$	—		$	1,837		$	(82,358	)	$	(5,660	)	$	(86,181	)
Balance at December 31, 2016	$	1,837		$	—		$	1,837		$	(82,358	)	$	(5,660	)	$	(86,181	)
Other comprehensive income (loss) before reclassifications	(1,180		)	(463		)	(1,643		)	(8,279		)	1,552			(8,370		)
Amounts reclassified from accumulated other comprehensive income	632			208			840			4,865			—			5,705
Other comprehensive income (loss) before tax	(548		)	(255		)	(803		)	(3,414		)	1,552			(2,665		)
Deferred taxes on current period activity	330			(59		)	271			13,820			—			14,091
Other comprehensive income (loss) after tax	(878		)	(196		)	(1,074		)	(17,234		)	1,552			(16,756		)
Balance at December 31, 2017	$	959		$	(196	)	$	763		$	(99,592	)	$	(4,108	)	$	(102,937	)