CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income		$ 52,960	$ 93,191	$ 110,519
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	[1]	936	(14,210)	4,385
Pension and other post-retirement benefit plans:
Net actuarial gain (loss) arising during period		(2,521)	856	2,598
Prior service cost arising during period		(190)	0	0
Reclassification adjustment for net actuarial loss included in net income		272	247	257
Reclassification adjustment for prior service costs included in net income		1	0	1
Reclassification adjustment for settlement losses included in net income		371	353	0
Total pension and other post-retirement benefit plans	[2]	(2,067)	1,456	2,856
Other comprehensive income (loss)		(1,131)	(12,754)	7,241
Comprehensive income		51,829	80,437	117,760
Comprehensive income attributable to noncontrolling interest		796	454	930
Comprehensive income attributable to Apergy		$ 51,033	$ 79,983	$ 116,830

[1] Net of income tax (expense) benefit of nil for the years ended December 31, 2019, 2018 and 2017, respectively.

[2] Net of income tax (expense) benefit of $347, $352 and $971 for the years ended December 31, 2019, 2018 and 2017, respectively.