Condensed Consolidating Financial Information - Condensed Statements of Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Total revenue	$ 247,748	$ 276,839	$ 306,170	$ 300,494	$ 313,133	$ 316,171	$ 305,747	$ 283,105	$ 1,131,251	$ 1,218,156	$ 1,010,466
Cost of goods and services									754,147	801,152	690,398
Gross profit	72,634	92,699	108,760	103,011	106,595	112,327	104,090	93,992	377,104	417,004	320,068
Selling, general and administrative expense									276,014	264,947	221,407
Interest expense, net									39,301	27,648	863
Other expense, net									2,603	3,056	9,443
Income before income taxes									59,186	121,353	88,355
Provision for (benefit from) income taxes									6,226	28,162	(22,164)
Income (loss) before equity in earnings of affiliates									52,960	93,191	110,519
Equity in earnings of affiliates									0	0	0
Net income	(1,574)	11,588	23,008	19,938	23,347	24,015	21,879	23,950	52,960	93,191	110,519
Net income attributable to noncontrolling interest									796	454	930
Net income attributable to Apergy	$ (1,823)	$ 11,394	$ 22,937	$ 19,656	$ 23,187	$ 23,961	$ 21,816	$ 23,773	52,164	92,737	109,589
Comprehensive income attributable to Apergy									51,033	79,983	116,830
Adjustments and eliminations
Condensed Income Statements, Captions [Line Items]
Total revenue									(43,886)	(43,682)	(36,103)
Cost of goods and services									(44,255)	(42,977)	(35,911)
Gross profit									369	(705)	(192)
Selling, general and administrative expense									0	0	0
Interest expense, net									0	0	0
Other expense, net									0	1	0
Income before income taxes									369	(706)	(192)
Provision for (benefit from) income taxes									76	(148)	(67)
Income (loss) before equity in earnings of affiliates									293	(558)	(125)
Equity in earnings of affiliates									(95,809)	(183,557)	(141,218)
Net income									(95,516)	(184,115)	(141,343)
Net income attributable to noncontrolling interest									0	0	0
Net income attributable to Apergy									(95,516)	(184,115)	(141,343)
Comprehensive income attributable to Apergy									(94,373)	(171,359)	(148,585)
Apergy Corporation
Condensed Income Statements, Captions [Line Items]
Total revenue									0	0	0
Cost of goods and services									0	0	0
Gross profit									0	0	0
Selling, general and administrative expense									271	1,614	0
Interest expense, net									38,673	26,973	0
Other expense, net									0	0	0
Income before income taxes									(38,944)	(28,587)	0
Provision for (benefit from) income taxes									(8,906)	(8,727)	0
Income (loss) before equity in earnings of affiliates									(30,038)	(19,860)	0
Equity in earnings of affiliates									82,202	112,597	109,589
Net income									52,164	92,737	109,589
Net income attributable to noncontrolling interest									0	0	0
Net income attributable to Apergy									52,164	92,737	109,589
Comprehensive income attributable to Apergy									51,033	79,983	116,830
Subsidiary Guarantors
Condensed Income Statements, Captions [Line Items]
Total revenue									1,005,032	1,091,565	882,062
Cost of goods and services									654,440	696,874	585,592
Gross profit									350,592	394,691	296,470
Selling, general and administrative expense									251,834	241,796	201,797
Interest expense, net									594	633	834
Other expense, net									937	1,322	10,169
Income before income taxes									97,227	150,940	83,670
Provision for (benefit from) income taxes									13,934	38,395	(10,510)
Income (loss) before equity in earnings of affiliates									83,293	112,545	94,180
Equity in earnings of affiliates									4,313	25,652	21,294
Net income									87,606	138,197	115,474
Net income attributable to noncontrolling interest									0	0	0
Net income attributable to Apergy									87,606	138,197	115,474
Comprehensive income attributable to Apergy									86,077	136,893	118,354
Subsidiary Non-guarantors
Condensed Income Statements, Captions [Line Items]
Total revenue									170,105	170,273	164,507
Cost of goods and services									143,962	147,255	140,717
Gross profit									26,143	23,018	23,790
Selling, general and administrative expense									23,909	21,537	19,610
Interest expense, net									34	42	29
Other expense, net									1,666	1,733	(726)
Income before income taxes									534	(294)	4,877
Provision for (benefit from) income taxes									1,122	(1,358)	(11,587)
Income (loss) before equity in earnings of affiliates									(588)	1,064	16,464
Equity in earnings of affiliates									9,294	45,308	10,335
Net income									8,706	46,372	26,799
Net income attributable to noncontrolling interest									796	454	930
Net income attributable to Apergy									7,910	45,918	25,869
Comprehensive income attributable to Apergy									8,296	34,466	30,231
Product revenue
Condensed Income Statements, Captions [Line Items]
Product and service revenue									1,000,630	1,090,218	922,692
Product revenue | Adjustments and eliminations
Condensed Income Statements, Captions [Line Items]
Product and service revenue									0	0	0
Product revenue | Apergy Corporation
Condensed Income Statements, Captions [Line Items]
Product and service revenue									0	0	0
Product revenue | Subsidiary Guarantors
Condensed Income Statements, Captions [Line Items]
Product and service revenue									884,355	965,057	799,337
Product revenue | Subsidiary Non-guarantors
Condensed Income Statements, Captions [Line Items]
Product and service revenue									116,275	125,161	123,355
Other revenue
Condensed Income Statements, Captions [Line Items]
Product and service revenue									130,621	127,938	87,774
Other revenue | Adjustments and eliminations
Condensed Income Statements, Captions [Line Items]
Product and service revenue									(43,886)	(43,682)	(36,103)
Other revenue | Apergy Corporation
Condensed Income Statements, Captions [Line Items]
Product and service revenue									0	0	0
Other revenue | Subsidiary Guarantors
Condensed Income Statements, Captions [Line Items]
Product and service revenue									120,677	126,508	82,725
Other revenue | Subsidiary Non-guarantors
Condensed Income Statements, Captions [Line Items]
Product and service revenue									$ 53,830	$ 45,112	$ 41,152