Consolidated statements of comprehensive income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 13,019	$ 24,684
Other comprehensive income, net of tax:
Foreign currency translation (net of tax effect of $0 and $0, respectively)	337	1,255
Retirement related benefit plans (net of tax effect of $0 and $10, respectively)	228	(12)
Total other comprehensive income	565	1,243
Comprehensive income	$ 13,584	$ 25,927

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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