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Net Income Attributable to IPG Photonics Corporation Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jul. 31, 2018	Jul. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded from computation of diluted weighted average common shares (in shares)	20,400	8,800	28,100	53,600
Share repurchase amount (no more than)					$ 125	$ 100
Stock repurchased during period (in shares)	371,228	17,328	585,806	215,860
Stock repurchase average price (in dollars per share)	$ 163.95	$ 161.55	$ 191.06	$ 124.67
Decrease in weighted average shares outstanding, treasury stock (in shares)	119,911	9,964	177,159	136,184
Restricted Stock Units, RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded from computation of diluted weighted average common shares (in shares)	10,500	3,800	18,400	14,900
Performance Stock Units, PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded from computation of diluted weighted average common shares (in shares)	5,100	0	5,900	2,800
Stock Options \| Non-qualified Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded from computation of diluted weighted average common shares (in shares)	4,800	5,000	3,800	35,900