Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Comprehensive Income [Abstract]
Net unrealized (loss) income on hedging derivatives, tax	$ (300)	$ (2,600)	$ 1,500
Reclassification adjustment for (gain) loss on settlement of hedging derivatives included in net earnings, tax effect	0	400	5,800
Foreign currency translation (loss) gain tax	0	0	0
Adjustment to early retiree medical plan, tax effect	514	(767)	(1,291)
Reclassification adjustment for gain on early retiree medical plan included in net earnings, tax effect	$ (108)	$ (279)	$ (309)

Statement Of Comprehensive Income [Abstract]

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Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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