CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock, Par Value	Common Stock, Capital in excess of par value	Retained Earnings	Net Parent Investment in Apergy	Accum. Other Comp. Loss	Non- controlling Interest
Beginning Balance at Dec. 31, 2016	$ 1,548,504	$ 0	$ 0	$ 0	$ 1,577,130	$ (33,657)	$ 5,031
Net income	110,519				109,589		930
Other comprehensive income (loss)	7,241					7,241
Distributions to noncontrolling interest	(1,212)						(1,212)
Net transfers to/from Dover	(29,543)				(29,543)
Ending Balance at Dec. 31, 2017	1,635,509	0	0	0	1,657,176	(26,416)	4,749
Net income	93,191			54,884	37,853		454
Other comprehensive income (loss)	(12,754)					(12,754)
Distributions to noncontrolling interest	(2,720)						(2,720)
Net transfers to/from Dover	(742,054)				(739,633)	(2,421)
Reclassification of net parent investment in Apergy	0		956,711		(956,711)
Issuance of common stock	0	773	(773)
Stock-based compensation	4,836	1	4,835
Other	(25)						(25)
Ending Balance at Dec. 31, 2018	975,983	774	960,773	54,884	0	(42,906)	2,458
Net income	52,960			52,164			796
Other comprehensive income (loss)	(1,131)					(1,131)
Stock-based compensation	10,250	1	10,249
Taxes withheld on issuance of stock-based awards	(1,848)		(1,848)
Ending Balance at Dec. 31, 2019	$ 1,036,214	$ 775	$ 969,174	$ 107,048	$ 0	$ (44,037)	$ 3,254