IPG Photonics (IPGP) 10-Q 5 Nov 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 04, 2019
Cover page.
Amendment Flag	false
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019
Entity Central Index Key	0001111928
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-33155
Entity Registrant Name	IPG PHOTONICS CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3444218
Entity Address, Address Line One	50 Old Webster Road
Entity Address, City or Town	Oxford
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01540
City Area Code	508
Local Phone Number	373-1100
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	IPGP
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding (in shares)		53,070,044

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 580,329	$ 544,358
Short-term investments	498,508	500,432
Accounts receivable, net	252,926	255,509
Inventories	417,163	403,579
Prepaid income taxes	50,693	43,782
Prepaid expenses and other current assets	65,896	57,764
Total current assets	1,865,515	1,805,424
Deferred income taxes, net	23,415	19,165
Goodwill	109,954	100,722
Intangible assets, net	85,561	87,139
Property, plant and equipment, net	596,138	543,068
Other assets	50,321	18,932
Total assets	2,730,904	2,574,450
Current liabilities:
Current portion of long-term debt	3,722	3,671
Accounts payable	30,466	36,302
Accrued expenses and other current liabilities	151,431	154,640
Income taxes payable	19,944	51,161
Total current liabilities	205,563	245,774
Deferred income taxes and other long-term liabilities	105,772	80,734
Long-term debt, net of current portion	38,909	41,707
Total liabilities	350,244	368,215
Commitments and contingencies (Note 12)
IPG Photonics Corporation equity:
Common stock, $0.0001 par value, 175,000,000 shares authorized; 54,662,933 and 53,035,843 shares issued and outstanding, respectively, at September 30, 2019; 54,371,701 and 52,941,607 shares issued and outstanding, respectively, at December 31, 2018	5	5
Treasury stock, at cost, 1,627,090 and 1,430,094 shares held at September 30, 2019 and December 31, 2018, respectively.	(250,919)	(224,998)
Additional paid-in capital	772,152	744,937
Retained earnings	2,033,184	1,848,500
Accumulated other comprehensive loss	(174,311)	(162,896)
Total IPG Photonics Corporation equity	2,380,111	2,205,548
Non-controlling interests	549	687
Total equity	2,380,660	2,206,235
Total liabilities and equity	$ 2,730,904	$ 2,574,450

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	175,000,000	175,000,000
Common stock, shares issued (in shares)	54,662,933	54,371,701
Common stock, shares outstanding (in shares)	53,035,843	52,941,607
Treasury stock, shares (in shares)	1,627,090	1,430,094

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 329,138	$ 356,346	$ 1,007,954	$ 1,129,823
Cost of sales	176,280	161,162	525,948	496,303
Gross profit	152,858	195,184	482,006	633,520
Operating expenses:
Sales and marketing	18,969	13,479	58,907	41,531
Research and development	32,160	30,909	99,528	91,268
General and administrative	26,776	25,245	82,526	74,857
Loss (gain) on foreign exchange	808	1,688	7,495	(1,489)
Total operating expenses	78,713	71,321	248,456	206,167
Operating income	74,145	123,863	233,550	427,353
Other income, net:
Interest income, net	3,734	3,884	11,737	4,925
Other (expense) income, net	(520)	423	129	1,252
Total other income	3,214	4,307	11,866	6,177
Income before provision for income taxes	77,359	128,170	245,416	433,530
Provision for income taxes	(20,232)	(27,418)	(60,852)	(104,827)
Net income	57,127	100,752	184,564	328,703
Less: net (loss) income attributable to non-controlling interests	(126)	235	(120)	235
Net income attributable to IPG Photonics Corporation	$ 57,253	$ 100,517	$ 184,684	$ 328,468
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ 1.08	$ 1.88	$ 3.48	$ 6.12
Diluted (in dollars per share)	$ 1.07	$ 1.84	$ 3.43	$ 5.97
Weighted average shares outstanding:
Basic (in shares)	52,928	53,571	53,073	53,677
Diluted (in shares)	53,622	54,696	53,864	54,995

Condensed Consolidated Statem_2

Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 57,127	$ 100,752	$ 184,564	$ 328,703
Other comprehensive income, net of tax:
Translation adjustments	(30,371)	(15,047)	(11,413)	(67,072)
Unrealized gain (loss) on derivatives	3	(5)	(2)	(3)
Effect of adopted accounting standards	0	0	0	10
Total other comprehensive loss	(30,368)	(15,052)	(11,415)	(67,065)
Comprehensive income	26,759	85,700	173,149	261,638
Comprehensive (loss) income attributable to non-controlling interests	(165)	196	(138)	196
Comprehensive income attributable to IPG Photonics Corporation	$ 26,924	$ 85,504	$ 173,287	$ 261,442

Condensed Consolidated Statem_3

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 184,564	$ 328,703
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	72,531	58,894
Deferred income taxes	(4,214)	2,954
Stock-based compensation	25,571	21,443
Unrealized loss (gain) on foreign currency transactions	7,033	(1,779)
Other	854	(1,936)
Provisions for inventory, warranty & bad debt	38,748	30,582
Changes in assets and liabilities that (used) provided cash:
Accounts receivable	(7,562)	(26,058)
Inventories	(51,032)	(122,051)
Prepaid expenses and other assets	11,087	(4,925)
Accounts payable	(8,137)	(1,319)
Accrued expenses and other liabilities	(26,113)	(20,095)
Income and other taxes payable	(49,748)	15,838
Net cash provided by operating activities	193,582	280,251
Cash flows from investing activities:
Purchases of and deposits on property, plant and equipment	(107,540)	(133,355)
Proceeds from sales of property, plant and equipment	348	755
Purchases of short-term and long-term investments	(557,674)	(566,498)
Proceeds from short-term investments	568,501	286,346
Acquisitions of businesses, net of cash acquired	(15,115)	(4,423)
Other	243	307
Net cash used in investing activities	(111,237)	(416,868)
Cash flows from financing activities:
Proceeds from line-of-credit facilities	15	255
Payments on line-of-credit facilities	(15)	(255)
Principal payments on long-term borrowings	(2,747)	(2,696)
Proceeds from issuance of common stock under employee stock option and purchase plans less payments for taxes related to net share settlement of equity awards	1,644	12,115
Cash contributed by non-controlling interests	0	378
Purchase of treasury stock, at cost	(25,921)	(111,926)
Net cash used in financing activities	(27,024)	(102,129)
Effect of changes in exchange rates on cash, cash equivalents and restricted cash	(16,561)	(23,548)
Net increase (decrease) in cash, cash equivalents and restricted cash	38,760	(262,294)
Cash and cash equivalents — Beginning of period	544,358	909,900
Cash, cash equivalents and restricted cash — End of period (Note 2)	583,118	647,606
Supplemental disclosure of cash flow information:
Cash paid for interest	1,655	2,402
Cash paid for income taxes	97,172	94,801
Non-cash transactions:
Demonstration units transferred from inventory to other assets	8,892	3,787
Inventory transferred to machinery and equipment	8,250	2,114
Changes in accounts payable related to property, plant and equipment	2,721	(3,337)
Leased assets obtained in exchange for new operating lease liabilities	$ 11,944	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements Of Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Non- controlling Interest
Balance, beginning of year (in shares) at Dec. 31, 2017		53,629,439	378,269
Balance, beginning of period at Dec. 31, 2017	$ 2,022,322	$ 5	$ (48,933)	$ 704,727	$ 1,443,867	$ (77,344)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		342,673
Exercise of stock options and vesting of RSU's and PSU's	9,827	$ 0		9,827
Purchased common stock (in shares)		(585,806)	(585,806)
Purchased common stock	(111,926)	$ 0	$ (111,926)
Stock-based compensation	21,443			21,443
Net income	328,703				328,468		235
Foreign currency translation adjustments	(67,111)					(67,072)	(39)
Unrealized gain (loss) on derivatives	(3)					(3)
Non-controlling interest of acquired company	649						649
Common stock issued under employee stock purchase plan (in shares)		12,198
Common stock issued under employee stock purchase plan	2,288	$ 0		2,288
Balance, end of period (in shares) at Sep. 30, 2018		53,398,504	964,075
Balance, end of period at Sep. 30, 2018	2,206,808	$ 5	$ (160,859)	738,285	1,772,941	(144,409)	845
Balance, beginning of year (in shares) at Jun. 30, 2018		53,724,445	592,847
Balance, beginning of period at Jun. 30, 2018	2,172,157	$ 5	$ (99,997)	729,082	1,672,424	(129,357)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		45,287
Exercise of stock options and vesting of RSU's and PSU's	1,484	$ 0		1,484
Purchased common stock (in shares)		(371,228)	(371,228)
Purchased common stock	(60,862)	$ 0	$ (60,862)
Stock-based compensation	7,719			7,719
Net income	100,752				100,517		235
Foreign currency translation adjustments	(15,086)					(15,047)	(39)
Unrealized gain (loss) on derivatives	(5)					(5)
Non-controlling interest of acquired company	649						649
Balance, end of period (in shares) at Sep. 30, 2018		53,398,504	964,075
Balance, end of period at Sep. 30, 2018	2,206,808	$ 5	$ (160,859)	738,285	1,772,941	(144,409)	845
Balance, beginning of year (in shares) at Dec. 31, 2018		52,941,607	1,430,094
Balance, beginning of period at Dec. 31, 2018	2,206,235	$ 5	$ (224,998)	744,937	1,848,500	(162,896)	687
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		259,749
Exercise of stock options and vesting of RSU's and PSU's	(2,321)	$ 0		(2,321)
Purchased common stock (in shares)		(196,996)	(196,996)
Purchased common stock	(25,921)	$ 0	$ (25,921)
Stock-based compensation	25,571			25,571
Net income	184,564				184,684		(120)
Foreign currency translation adjustments	(11,431)					(11,413)	(18)
Unrealized gain (loss) on derivatives	(2)					(2)
Common stock issued under employee stock purchase plan (in shares)		31,483
Common stock issued under employee stock purchase plan	3,965	$ 0		3,965
Balance, end of period (in shares) at Sep. 30, 2019		53,035,843	1,627,090
Balance, end of period at Sep. 30, 2019	2,380,660	$ 5	$ (250,919)	772,152	2,033,184	(174,311)	549
Balance, beginning of year (in shares) at Jun. 30, 2019		53,182,910	1,446,470
Balance, beginning of period at Jun. 30, 2019	2,367,361	$ 5	$ (227,282)	761,936	1,975,931	(143,943)	714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		33,553
Exercise of stock options and vesting of RSU's and PSU's	1,676	$ 0		1,676
Purchased common stock (in shares)		(180,620)	(180,620)
Purchased common stock	(23,637)	$ 0	$ (23,637)
Stock-based compensation	8,540			8,540
Net income	57,127				57,253		(126)
Foreign currency translation adjustments	(30,410)					(30,371)	(39)
Unrealized gain (loss) on derivatives	3					3
Balance, end of period (in shares) at Sep. 30, 2019		53,035,843	1,627,090
Balance, end of period at Sep. 30, 2019	$ 2,380,660	$ 5	$ (250,919)	$ 772,152	$ 2,033,184	$ (174,311)	$ 549

Basis Of Presentation And Signi

Basis Of Presentation And Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared by IPG Photonics Corporation, or "IPG", "its" or the "Company". Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC"). The condensed consolidated financial statements include the Company's accounts and those of its subsidiaries. All intercompany balances have been eliminated in consolidation. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto in the Company's Annual Report on Form 10-K for the year ended December 31, 2018. In the opinion of the Company's management, the financial information for the interim periods presented reflects all adjustments necessary for a fair presentation of the Company's financial position, results of operations and cash flows. The results reported in these condensed consolidated financial statements are not necessarily indicative of results that may be expected for the entire year. In accordance with Accounting Standards Codification ("ASC") 842, "Leases," ("ASC 842" or the "new lease standard"), the following significant accounting policy has been adopted as of January 1, 2019. Leases — The Company determines if an arrangement is a lease at inception. Operating leases are included in other assets, other current liabilities, and other long-term liabilities on our condensed consolidated balance sheets. Right of use ("ROU") assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of the Company's leases do not provide an implicit rate, IPG uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The ROU assets also include any lease payments made and initial direct costs incurred and exclude lease incentives. Lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Leases with an initial term of 12 months or less are not recorded on the balance sheet; the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for as a single lease component. Reclassifications — Certain prior year amounts have been reclassified to conform with current period presentation. These reclassifications had no effect on the reported results of operations.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Adopted Pronouncements — In February 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard related to leases to increase transparency and comparability among organizations by requiring the recognition of ROU assets and lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. The Company adopted ASC 842, as of January 1, 2019, using the modified retrospective approach as of the date of adoption. Under this approach, comparative periods have not been restated. In addition, IPG elected the package of three practical expedients permitted under the transition guidance within the new standard, which among other things, allowed for the carry forward of the historical lease classification. The cumulative effect of the changes made to the Company's condensed consolidated January 1, 2019 balance sheet for the adoption of ASC 842 related to operating leases was as follows: Balance at Adoption of Balance at December 31, 2018 ASC 842 January 1, 2019 Balance Sheet Prepaid expenses and other current assets $ 57,764 $ (324) $ 57,440 Other assets 18,932 19,463 38,395 Accrued expenses and other current liabilities 154,640 5,292 159,932 Deferred income taxes and other long-term liabilities 80,734 13,847 94,581 In the first quarter of 2018, the Company adopted FASB ASU No. 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash" ("ASU 2016-18"), which enhances and clarifies the guidance on the classification and presentation of restricted cash in the statement of cash flows and requires additional disclosure about restricted cash balances. The Company considers cash to be restricted when withdrawal or general use is legally restricted. The Company records restricted cash in other assets on the condensed consolidated balance sheets and determines classification based on the expected duration of the restriction. The reconciliation of the Company's cash and cash equivalents in the condensed consolidated balance sheets to cash, cash equivalents and restricted cash in the condensed consolidated statement of cash flows is as follows: Balance at September 30, 2019 Cash and cash equivalents $ 580,329 Restricted cash included in other assets 2,789 Cash, cash equivalents and restricted cash $ 583,118 Other Pronouncements Currently Under Evaluation — In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments" ("ASU 2016-13"), which adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of expected credit losses, which the FASB believes will result in more timely recognition of such losses. The ASU is also intended to reduce the complexity by decreasing the number of credit impairment models that entities use to account for debt instruments. ASU 2016-03, along with its subsequent clarifications, is effective for fiscal years beginning after December 15, 2019. The Company does not expect this standard will have a material impact to net income.

Revenue From Contracts With Cus

Revenue From Contracts With Customers	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue From Contracts With Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS The following tables represent a disaggregation of revenue from contracts with customers: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Sales by Application Materials processing $ 306,260 $ 334,498 $ 952,936 $ 1,065,712 Other applications 22,878 21,848 55,018 64,111 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Sales by Product High Power Continuous Wave ("CW") Lasers $ 184,924 $ 227,462 $ 577,354 $ 724,111 Medium and Low Power CW Lasers 11,891 19,101 42,904 75,472 Pulsed Lasers 33,850 35,408 106,100 115,243 Quasi-Continuous Wave ("QCW") Lasers 12,479 18,276 42,612 54,568 Laser and Non-Laser Systems 32,929 14,701 104,943 37,600 Other Revenue including Amplifiers, Service, Parts, Accessories and Change in Deferred Revenue 53,065 41,398 134,041 122,829 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Sales by Geography North America $ 71,000 $ 53,762 $ 199,947 $ 140,704 Europe: Germany 17,204 21,714 59,487 86,939 Other including Eastern Europe/CIS 62,196 66,392 192,527 225,717 Asia and Australia: China 121,290 158,853 399,246 511,852 Japan 21,859 21,871 54,879 60,927 Other 28,877 31,953 89,544 99,476 Rest of World 6,712 1,801 12,324 4,208 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Timing of Revenue Recognition Goods and services transferred at a point in time $ 310,324 $ 355,191 $ 944,454 $ 1,126,285 Goods and services transferred over time 18,814 1,155 63,500 3,538 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 One of our customers accounted for 9% and 13% of our net sales for the nine months ended September 30, 2019 and 2018, respectively. The same customer accounted for 29% and 25% of our net accounts receivable as of September 30, 2019 and December 31, 2018, respectively. The Company enters into contracts to sell lasers and spare parts, for which revenue is generally recognized upon shipment or delivery, depending on the terms of the contract. The Company also provides installation services and extended warranties. The Company frequently receives consideration from a customer prior to transferring goods to the customer under the terms of a sales contract. The Company records customer deposits related to these prepayments, which represent a contract liability. The Company also records deferred revenue related to installation services when consideration is received before the services have been performed. The Company recognizes customer deposits and deferred revenue as net sales after control of the goods or services has been transferred to the customer and all revenue recognition criteria are met. The Company bills customers for extended warranties upon entering into the agreement with the customer, resulting in deferred revenue. The timing of customer payments on contracts for the sale of customized robotic systems generally differs from the timing of revenue recognized, resulting in contract assets and liabilities. Contract assets are included within prepaid expense and other current assets on the condensed consolidated balance sheets. Contract liabilities are included within accrued expenses and other current liabilities on the condensed consolidated balance sheets. The following table reflects the changes in the Company's contract assets and liabilities for the nine months ended September 30, 2019 and 2018: September 30, January 1, September 30, January 1, 2019 2019 Change 2018 2018 Change Contract assets Contract assets $ 10,606 $ 10,102 $ 504 $ — $ — $ — Contract liabilities Contract liabilities - current 49,358 52,606 (3,248) 48,274 46,508 1,766 Contract liabilities - long-term 1,677 1,413 264 1,374 182 1,192 During the three months ended September 30, 2019 and September 30, 2018 the Company recognized revenue of $4,534 and $3,355, respectively, that was included in contract liabilities at the beginning of each period. During the nine months ended September 30, 2019 and September 30, 2018, the Company recognized revenue of $40,786 and $38,885, respectively, that was included in contract liabilities at the beginning of each period. The Company has elected the practical expedient in ASC 606-10-50-14, whereby the performance obligations for contracts with an original expected duration of one year or less are not disclosed. The following table represents the Company's remaining performance obligations from contracts that are recognized over time as of September 30, 2019: Remaining Performance Obligations 2019 (a) 2020 2021 2022 2023 2024 and thereafter Total Revenue expected to be recognized for extended warranty agreements $ 1,432 $ 3,395 $ 545 $ 297 $ 120 $ 14 $ 5,803 Revenue to be earned over time from contracts to sell robotic systems 16,061 6,659 — — — — 22,720 Total $ 17,493 $ 10,054 $ 545 $ 297 $ 120 $ 14 $ 28,523 (a) For the three-month period beginning October 1, 2019.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Company's financial instruments consist of cash equivalents, short-term and long-term investments, accounts receivable, auction rate securities, accounts payable, drawings on revolving lines of credit, long-term debt, interest rate swaps and contingent purchase consideration. The valuation techniques used to measure fair value are based upon observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect internal market assumptions. These two types of inputs create the following fair value hierarchy: Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions. The carrying amounts of money market fund deposits, term deposits, accounts receivable, accounts payable and drawings on revolving lines of credit are considered reasonable estimates of their fair market value due to the short maturity of most of these instruments or as a result of the competitive market interest rates which have been negotiated. The Company's bond securities are reported at fair value based upon quoted prices for instruments with identical terms in active markets. The Company's commercial paper securities reported at fair value are based upon model-driven valuations in which all significant inputs are observable or can be derived from or corroborated by observable market data for substantially the full term of the asset or liability, and are therefore classified as Level 2. At September 30, 2019 and December 31, 2018, the Company's long-term notes consisted of a variable rate note and a fixed rate note, and the book value is considered a reasonable estimate of fair market value. The following table presents fair value information related to the Company's assets and liabilities measured at amortized cost on the condensed consolidated balance sheets with the exception of the interest rate swap, which is measured at fair value: Fair Value Measurements at September 30, 2019 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market fund deposits and term deposits $ 123,243 $ 123,243 $ — $ — Commercial paper 56,831 — 56,831 — Short-term investments: U.S. Treasury and agency obligations 20,971 20,971 — — Corporate bonds 270,911 270,911 — — Non-U.S. government bonds 3,000 — 3,000 — Commercial paper 197,453 — 197,453 — Certificate of deposit 6,498 6,498 — — Long-term investments and other assets: Auction rate securities 590 — — 590 Interest rate swap 32 — 32 — Total $ 679,529 $ 421,623 $ 257,316 $ 590 Liabilities Long-term debt $ 42,631 $ — $ 42,631 $ — Contingent purchase consideration 297 — — 297 Total $ 42,928 $ — $ 42,631 $ 297 Fair Value Measurements at December 31, 2018 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market fund deposits and term deposits $ 180,965 $ 180,965 $ — $ — U.S. Treasury and agency obligations 6,495 6,495 — — Commercial paper 78,948 — 78,948 — Short-term investments: U.S. Treasury and agency obligations 116,800 116,800 — — Corporate bonds 227,009 227,009 — — Commercial paper 156,321 — 156,321 — Long-term investments and other assets: Corporate bonds 3,859 3,859 — — Auction rate securities 847 — — 847 Interest rate swaps 31 — 31 — Total $ 771,275 $ 535,128 $ 235,300 $ 847 Liabilities Long-term debt $ 45,378 $ — $ 45,378 $ — Contingent purchase consideration 898 — — 898 Total $ 46,276 $ — $ 45,378 $ 898 The fair value of the short-term investments considered held-to-maturity as of September 30, 2019 and December 31, 2018 was $498,833 and $500,130, respectively, which include an unrealized gain of $325 and unrealized loss of $302, respectively, as compared to the book value recorded on the condensed consolidated balance sheets for the same periods. There were no long-term investments considered held-to-maturity as of September 30, 2019. The fair value of the long-term investments considered held-to-maturity as of December 31, 2018 was $3,859, which represents the book value recorded within other assets on the condensed consolidated balance sheets for the same period. There were no impairments for the investments considered held-to-maturity at September 30, 2019 and December 31, 2018. The Company entered into an interest rate swap that is designated as a cash flow hedge associated with a new long-term note issued during the second quarter of 2016 that will terminate with the long-term note in May 2023. The fair value at September 30, 2019 for the interest rate swap considered pricing models whose inputs are observable for the securities held by the Company. Auction rate securities and contingent consideration are measured at fair value on a recurring basis using significant unobservable inputs (Level 3). The fair value of the auction rate securities was determined using prices observed in inactive markets with limited observable data for the securities held by the Company. The auction rate securities are considered available-for-sale securities. They had a cost basis of $590 and $847 at September 30, 2019 and December 31, 2018, respectively. There were no impairments for the investments considered available-for-sale during the quarters ended September 30, 2019 and 2018. The fair value of contingent consideration was determined using an income approach at the respective business combination date and at the reporting date. That approach is based on significant inputs that are not observable in the market and include key assumptions such as assessing the probability of meeting certain milestones required to earn the contingent consideration. The following table presents information about the Company's movement in Level 3 assets and liabilities measured at fair value: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Auction rate securities Balance, beginning of period $ 852 $ 1,174 $ 847 $ 1,016 Redemptions (264) (207) (264) (207) Change in fair value and accretion 2 — 7 158 Balance, end of period $ 590 $ 967 $ 590 $ 967 Contingent purchase consideration Balance, beginning of period $ 300 $ 902 $ 898 $ 902 Cash payments — — (632) — Foreign exchange adjustment (3) — 31 — Balance, end of period $ 297 $ 902 $ 297 $ 902 The following table presents the effective maturity dates of held-to-maturity and available-for-sale debt investments as of September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 Book Value Fair Value Book Value Fair Value Investment maturity Held-to-maturity: Less than 1 year $ 498,508 $ 498,833 $ 585,875 $ 585,573 1 through 5 years — — 3,859 3,859 Total $ 498,508 $ 498,833 $ 589,734 $ 589,432 Available-for-sale: Greater than 5 years $ 590 $ 590 $ 847 $ 847

Inventories

Inventories	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventories	INVENTORIES Inventories consist of the following: September 30, December 31, 2019 2018 Components and raw materials $ 235,276 $ 233,594 Work-in-process 49,744 66,498 Finished components and devices 132,143 103,487 Total $ 417,163 $ 403,579 The Company recorded inventory provisions totaling $7,303 and $3,076 for the three months ended September 30, 2019 and 2018, respectively, and $19,952 and $9,930 for the nine months ended September 30, 2019 and 2018, respectively. These provisions relate to the recoverability of the value of inventories due to technological changes and excess quantities. These provisions are reported as a reduction to components and raw materials and finished components and devices.

Goodwill And Intangibles

Goodwill And Intangibles	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	GOODWILL AND INTANGIBLES The following table sets forth the changes in the carrying amount of goodwill for the nine months ended September 30, 2019: Amount Balance at January 1 $ 100,722 Goodwill arising from acquisition 9,426 Adjustment to goodwill during measurement period 448 Foreign exchange adjustment (642) Balance at September 30 $ 109,954 During the fourth quarter of 2018, the Company acquired 100% of the membership units of Genesis Systems Group, LLC ("Genesis"). During the first quarter of 2019, the working capital adjustment to the purchase price was finalized resulting in an increase in the purchase price of $448. The additional purchase price was allocated entirely to goodwill. During the first quarter of 2019, the Company acquired the submarine networks division (SND) of Padtec SA, a communications equipment company based in Brazil. SND is a provider of submarine networking technology and systems. The Company paid $19,560 to acquire SND, which represents the fair value on that date. Of the purchase price, $1,956 ($1,801 at September 30, 2019) was held back for potential post-closing adjustments related to government approval of licenses. This balance is included within accrued expenses and other liabilities on the condensed consolidated balance sheets. In addition, $2,934 ($2,789 at September 30, 2019) was held back in a restricted bank account for potential post-closing adjustments related to indemnities provided by the seller. This balance related to restricted cash is included within other assets, and the liability related to the amount due to the sellers if the indemnities are satisfied is included within deferred income taxes and other long-term liabilities on the condensed consolidated balance sheets. Any excess of the acquisition consideration over the fair value of assets acquired and liabilities assumed is allocated to goodwill, which amounted to $9,426. The Company is assessing the deductibility of the goodwill for tax purposes. As a result of the acquisition, the Company recorded intangible assets of $4,825 related to production know-how with a weighted-average useful life of 6 years and $4,825 related to customer relationships with a weighted-average life of 6 years. The purchase price allocations included in the Company's condensed consolidated financial statements are not complete. They represent the preliminary fair value estimates as of September 30, 2019 and are subject to subsequent adjustment as the Company obtains additional information during the measurement period and finalizes its fair value estimates. Any subsequent adjustments to these fair value estimates occurring during the measurement period will result in changes to the amounts and allocations recorded. Intangible assets, subject to amortization, consisted of the following: September 30, 2019 December 31, 2018 Gross Carrying Accumulated Net Carrying Weighted- Average Lives Gross Carrying Accumulated Net Carrying Weighted- Customer relationships $ 62,241 $ (10,963) $ 51,278 10 years $ 57,849 $ (6,427) $ 51,422 11 years Technology, trademark and tradename 41,350 (14,779) 26,571 7 years 41,184 (10,474) 30,710 7 years Production know-how 13,581 (7,469) 6,112 7 years 9,211 (6,212) 2,999 7 years Patents 8,036 (6,436) 1,600 8 years 8,036 (6,028) 2,008 8 years Total $ 125,208 $ (39,647) $ 85,561 $ 116,280 $ (29,141) $ 87,139 Amortization expense for the three months ended September 30, 2019 and 2018 was $3,617 and $1,982, respectively. Amortization expense for the nine months ended September 30, 2019 and 2018 was $10,581 and $5,821, respectively. The estimated future amortization expense for intangibles for the remainder of 2019 and subsequent years is as follows: 2019 (a) 2020 2021 2022 2023 Thereafter Total $ 3,586 $ 13,562 13,197 $ 12,280 $ 11,350 $ 31,586 $ 85,561 (a) For the three-month period beginning October 1, 2019.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	LEASES The Company leases certain warehouses, office spaces, land, vehicles and equipment under operating lease agreements. The remaining terms of these leases range from less than 1 year to 46 years. The operating lease expense for the three and nine months ended September 30, 2019 was $2,168 and $6,632, respectively. The cash paid for amounts included in the measurement of lease liabilities included in the operating cash flows from operating leases was $1,679 and $5,121 for the three and nine months ended September 30, 2019, respectively. The Company does not have any finance lease arrangements. The Company's operating lease assets and lease liabilities consist of the following as of September 30, 2019: Account Classification Amount Right-of-use assets Other assets $ 26,304 Short-term lease liabilities Accrued expenses and other liabilities 5,315 Long-term lease liabilities Deferred income taxes and other long-term liabilities 21,153 Total lease liabilities $ 26,468 The table below presents the future minimum lease payments to be made under non-cancelable operating leases as of December 31, 2018: Years ending December 31, 2019 $ 6,314 2020 4,603 2021 3,358 2022 2,596 2023 2,078 Thereafter 11,340 Total $ 30,289 The table below presents the maturities of operating lease liabilities as of September 30, 2019: 2019 (a) $ 1,617 2020 5,683 2021 4,562 2022 3,452 2023 2,880 Thereafter 12,472 Total future minimum lease payments 30,666 Less: imputed interest (4,198) Present value of lease liabilities $ 26,468 (a) For the three-month period beginning October 1, 2019. Other information relevant to the Company's operating leases consist of the following as of September 30, 2019: Weighted-average remaining lease term 9 years Weighted-average discount rate 3.61 %

Accrued Expenses And Other Liab

Accrued Expenses And Other Liabilities	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Expenses And Other Liabilities	ACCRUED EXPENSES AND OTHER LIABILITIES Accrued expenses and other liabilities consist of the following: September 30, December 31, 2019 2018 Accrued compensation $ 57,939 $ 60,107 Contract liabilities 49,358 52,606 Current portion of accrued warranty 23,802 23,106 Short-term lease liabilities 5,315 — Other 15,017 18,821 Total $ 151,431 $ 154,640

Product Warranties

Product Warranties	9 Months Ended
	Sep. 30, 2019
Product Warranties Disclosures [Abstract]
Product Warranties	PRODUCT WARRANTIES The Company typically provides 1 to 3 years parts and service warranties on lasers, laser and non-laser systems, and amplifiers. Most of the Company's sales offices provide support to customers in their respective geographic areas. Warranty reserves have generally been sufficient to cover product warranty repair and replacement costs. The following table summarizes product warranty accrual activity recorded during the nine months ended September 30, 2019 and 2018. 2019 2018 Balance at January 1 $ 51,422 $ 47,517 Provision for warranty accrual 16,916 19,050 Warranty claims (17,399) (13,827) Foreign currency translation (1,077) (1,057) Balance at September 30 $ 49,862 $ 51,683 Accrued warranty reported in the accompanying condensed consolidated financial statements as of September 30, 2019 and December 31, 2018 consisted of $23,802 and $23,106 in accrued expenses and other liabilities, respectively, and $26,060 and $28,316 in other long-term liabilities, respectively.

Financing Arrangements

Financing Arrangements	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Financing Arrangements	FINANCING ARRANGEMENTS The Company's borrowings under existing financing arrangements consist of the following: September 30, December 31, 2019 2018 Long-term notes $ 42,631 $ 45,378 Less: current portion (3,722) (3,671) Total long-term debt $ 38,909 $ 41,707 At September 30, 2019, the Company has an unsecured long-term note with an outstanding principal balance of $19,891, of which, $1,188 is the current portion. The interest on this unsecured long-term note is variable at 1.2% above LIBOR and is fixed using an interest rate swap at 2.9% per annum. The unsecured long-term note matures in May 2023, at which time the outstanding principal balance will be $15,438. Also at September 30, 2019, the Company has another long-term note that is secured by its corporate aircraft with an outstanding principal balance of $22,740, of which, $2,534 is the current portion. The interest on this collateralized long-term note is fixed at 2.7% per annum. The collateralized long-term note matures in July 2022, at which time the outstanding principal balance will be $15,375.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	DERIVATIVE FINANCIAL INSTRUMENTS The Company's only outstanding derivative financial instrument is an interest rate swap that is classified as a cash flow hedge of its variable rate debt. The fair value amounts in the condensed consolidated balance sheets were: Notional Amounts (1) Other Assets September 30, December 31, September 30, December 31, 2019 2018 2019 2018 $ 19,891 $ 20,781 $ 32 $ 31 (1) Notional amounts represent the gross contract/notional amount of the derivatives outstanding. The derivative gains and losses in the condensed consolidated financial statements for the three and nine months ended September 30, 2019 and 2018, related to the Company's current and previous interest rate swap contracts were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Effective portion recognized in other comprehensive income, pretax: Interest rate swap $ 4 $ (5) $ 1 $ (3)

Commitments And Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIESFrom time to time, the Company may be involved in disputes and legal proceedings in the ordinary course of its business. These proceedings may include allegations of infringement of intellectual property, commercial disputes and employment matters. As of September 30, 2019 and through the filing date of these condensed consolidated financial statements, the Company has no legal proceedings ongoing that management estimates could have a material effect on the Company's condensed consolidated financial statements.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The effective tax rates for the three months ended September 30, 2019 and 2018 were 26.2% and 21.4%, respectively. For the nine months ended September 30, 2019 and 2018, the effective tax rates were 24.8% and 24.2%, respectively. There were discrete tax benefits of $5,443 and $660 for the three months ended September 30, 2019 and 2018, respectively. The discrete benefits for the three months ended September 30, 2019 include $229 related to excess equity-based compensation deductions and $5,326 for return to provision adjustments. The discrete benefits for the three months ended September 30, 2018 include $1,026 related to excess equity-based compensation and $4,247 for return to provision adjustments. The benefits for the three months ended September 30, 2018 were offset by discrete detriments of $2,195 related to prepaid income taxes on profit in inventory provided as of December 31, 2017 at a U.S. Federal Tax Rate of 35% that flowed through consolidated earnings in 2018 and $3,046 related to a valuation allowance reflected primarily for state tax credits that exceed state income taxes in specific states . For the nine months ended September 30, 2019 and 2018, the discrete tax benefits were $8,357 and $5,178, respectively. The discrete benefits for the nine months ended September 30, 2019 include $4,271 related to excess equity-based compensation deductions and $5,293 for return to provision adjustments . The discrete benefits for the nine months ended September 30, 2018 include $10,920 related to excess equity-based compensation and $4,001 related to provision to return adjustments. The benefits for the nine months ended September 30, 2018 were offset by discrete detriments of $6,584 related to prepaid income taxes on profit in inventory provided as of December 31, 2017 at a U.S. Federal Tax Rate of 35% that flowed through consolidated earnings in 2018 and $3,046 related to a valuation allowance reflected primarily for state tax credits that exceed state income taxes in specific states. In addition to the discrete items above, the effective tax rate for the three months ended September 30, 2018 benefited from certain tax adjustments made in accordance with SAB 118. SAB 118 provided guidance on accounting for the tax effects of the Tax Cuts and Jobs Act and allowed a measurement period of up to one year from enactment to complete the accounting under ASC 740. The Company reduced its annual effective rate because of changes in the Global Intangible Low Taxed Income ("GILTI") tax calculation resulting from newly proposed regulations issued by the Treasury. The impact reduced the estimated tax expense for the nine months ended September 30, 2018 by $7,939, of which $4,747 had been reflected in tax expense as of June 30, 2018. The Company accounts for its uncertain tax positions in accordance with the accounting standards for income taxes. The Company continues to classify interest and penalties related to unrecognized tax benefits as a component of the provision for income taxes. The following is a summary of the activity of the Company’s unrecognized tax benefits for nine months ended September 30, 2019 and 2018: 2019 2018 Balance at January 1, $ 11,206 $ 10,370 Change in prior period positions — (1,067) Additions for tax positions in current period 3,342 1,012 Foreign currency translation (84) (771) Balance at September 30, $ 14,464 $ 9,544

Net Income Attributable To IPG

Net Income Attributable To IPG Photonics Corporation Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income Attributable To IPG Photonics Corporation Per Share	NET INCOME ATTRIBUTABLE TO IPG PHOTONICS CORPORATION PER SHARE The following table sets forth the computation of diluted net income attributable to IPG Photonics Corporation per share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net income attributable to IPG Photonics Corporation $ 57,253 $ 100,517 $ 184,684 $ 328,468 Net income attributable to common stockholders 57,253 100,517 184,684 328,468 Weighted average shares 52,928 53,571 53,073 53,677 Dilutive effect of common stock equivalents 694 1,125 791 1,318 Diluted weighted average common shares 53,622 54,696 53,864 54,995 Basic net income attributable to IPG Photonics Corporation per share $ 1.08 $ 1.88 $ 3.48 $ 6.12 Basic net income attributable to common stockholders $ 1.08 $ 1.88 $ 3.48 $ 6.12 Diluted net income attributable to IPG Photonics Corporation per share $ 1.07 $ 1.84 $ 3.43 $ 5.97 Diluted net income attributable to common stockholders $ 1.07 $ 1.84 $ 3.43 $ 5.97 For the three months ended September 30, 2019 and 2018, respectively, the computation of diluted weighted average common shares excludes 975,700 and 349,700 common stock equivalents because the effect of including them would be anti-dilutive. The shares excluded for the three months ended September 30, 2019 and 2018, respectively are comprised of 167,200 and 73,600 restricted stock units ("RSUs") and 45,500 and 17,300 performance stock units ("PSUs"), and 763,000 and 258,800 non-qualified stock options, respectively. For the nine months ended September 30, 2019 and 2018, respectively, the computation of diluted weighted average common shares excludes 768,000 and 256,500 common stock equivalents because the effect of including them would be anti-dilutive. The shares excluded for the nine months ended September 30, 2019 and 2018, respectively are comprised of 149,200 and 54,800 restricted stock units ("RSUs") and 40,800 and 14,000 performance stock units ("PSUs"), and 578,000 and 187,700 non-qualified stock options, respectively. On February 12, 2019, the Company announced that its board of directors authorized a new anti-dilutive stock repurchase program (the "2019 Program") following the completion of its $125,000 repurchase program (the "2018 Program") authorized in July 2018. Under the 2019 Program, IPG is authorized to repurchase shares of common stock in an amount not to exceed the lesser of (a) the number of shares issued to employees and directors under the Company's various employee and director equity compensation and employee stock purchase plans from January 1, 2019 through December 31, 2020 and (b) $125,000, exclusive of any fees, commissions or other expenses. Share repurchases will be made periodically in open market transactions using the Company's working capital, and are subject to market conditions, legal requirements and other factors. The 2019 Program authorization does not obligate the Company to repurchase any dollar amount or number of its shares, and repurchases may be commenced or suspended from time to time without prior notice. For the three months ended September 30, 2019, the Company repurchased 180,620 shares of common stock under the 2019 Program with an average price of $130.87 per share in the open market. The impact on the reduction of weighted average shares for the three months ended September 30, 2019 was 125,538 shares. For the nine months ended September 30, 2019, the Company repurchased 196,000 shares of common stock under the 2019 Program with an average price of $132.25 per share in the open market. The impact on the reduction of weighted average shares for the nine months ended September 30, 2019 was 48,080 shares. As of September 30, 2019 the remaining amount authorized under the 2019 Program is up to $99,000, but may be less depending upon the equity compensation and employee stock purchase plan dilution during the 2019 Program. For the three months ended September 30, 2018, the Company repurchased 371,228 shares of its common stock under the 2018 Program with an average price of $163.95 per share in the open market. The impact on the reduction of weighted average shares for the three months ended September 30, 2018 was 119,911 shares. For the nine months ended September 30, 2018, the Company repurchased 585,806 shares of its common stock with an average price of $191.06 per share in the open market. The impact on the reduction of weighted average shares for the nine months ended September 30, 2018 was 177,159 shares.

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared by IPG Photonics Corporation, or "IPG", "its" or the "Company". Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC"). The condensed consolidated financial statements include the Company's accounts and those of its subsidiaries. All intercompany balances have been eliminated in consolidation. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto in the Company's Annual Report on Form 10-K for the year ended December 31, 2018.
Leases	Leases — The Company determines if an arrangement is a lease at inception. Operating leases are included in other assets, other current liabilities, and other long-term liabilities on our condensed consolidated balance sheets. Right of use ("ROU") assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of the Company's leases do not provide an implicit rate, IPG uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The ROU assets also include any lease payments made and initial direct costs incurred and exclude lease incentives. Lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Leases with an initial term of 12 months or less are not recorded on the balance sheet; the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for as a single lease component.
Reclassifications	Reclassifications — Certain prior year amounts have been reclassified to conform with current period presentation. These reclassifications had no effect on the reported results of operations.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Adopted Pronouncements — In February 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard related to leases to increase transparency and comparability among organizations by requiring the recognition of ROU assets and lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. The Company adopted ASC 842, as of January 1, 2019, using the modified retrospective approach as of the date of adoption. Under this approach, comparative periods have not been restated. In addition, IPG elected the package of three practical expedients permitted under the transition guidance within the new standard, which among other things, allowed for the carry forward of the historical lease classification. The cumulative effect of the changes made to the Company's condensed consolidated January 1, 2019 balance sheet for the adoption of ASC 842 related to operating leases was as follows: Balance at Adoption of Balance at December 31, 2018 ASC 842 January 1, 2019 Balance Sheet Prepaid expenses and other current assets $ 57,764 $ (324) $ 57,440 Other assets 18,932 19,463 38,395 Accrued expenses and other current liabilities 154,640 5,292 159,932 Deferred income taxes and other long-term liabilities 80,734 13,847 94,581 In the first quarter of 2018, the Company adopted FASB ASU No. 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash" ("ASU 2016-18"), which enhances and clarifies the guidance on the classification and presentation of restricted cash in the statement of cash flows and requires additional disclosure about restricted cash balances. The Company considers cash to be restricted when withdrawal or general use is legally restricted. The Company records restricted cash in other assets on the condensed consolidated balance sheets and determines classification based on the expected duration of the restriction. The reconciliation of the Company's cash and cash equivalents in the condensed consolidated balance sheets to cash, cash equivalents and restricted cash in the condensed consolidated statement of cash flows is as follows: Balance at September 30, 2019 Cash and cash equivalents $ 580,329 Restricted cash included in other assets 2,789 Cash, cash equivalents and restricted cash $ 583,118 Other Pronouncements Currently Under Evaluation — In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments" ("ASU 2016-13"), which adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of expected credit losses, which the FASB believes will result in more timely recognition of such losses. The ASU is also intended to reduce the complexity by decreasing the number of credit impairment models that entities use to account for debt instruments. ASU 2016-03, along with its subsequent clarifications, is effective for fiscal years beginning after December 15, 2019. The Company does not expect this standard will have a material impact to net income.

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Cumulative Effect of Change to Balance Sheet	The cumulative effect of the changes made to the Company's condensed consolidated January 1, 2019 balance sheet for the adoption of ASC 842 related to operating leases was as follows: Balance at Adoption of Balance at December 31, 2018 ASC 842 January 1, 2019 Balance Sheet Prepaid expenses and other current assets $ 57,764 $ (324) $ 57,440 Other assets 18,932 19,463 38,395 Accrued expenses and other current liabilities 154,640 5,292 159,932 Deferred income taxes and other long-term liabilities 80,734 13,847 94,581
Schedule of Cash and Cash Equivalents	The reconciliation of the Company's cash and cash equivalents in the condensed consolidated balance sheets to cash, cash equivalents and restricted cash in the condensed consolidated statement of cash flows is as follows: Balance at September 30, 2019 Cash and cash equivalents $ 580,329 Restricted cash included in other assets 2,789 Cash, cash equivalents and restricted cash $ 583,118
Schedule of Restricted Cash	The reconciliation of the Company's cash and cash equivalents in the condensed consolidated balance sheets to cash, cash equivalents and restricted cash in the condensed consolidated statement of cash flows is as follows: Balance at September 30, 2019 Cash and cash equivalents $ 580,329 Restricted cash included in other assets 2,789 Cash, cash equivalents and restricted cash $ 583,118

Revenue From Contracts With C_2

Revenue From Contracts With Customers (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables represent a disaggregation of revenue from contracts with customers: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Sales by Application Materials processing $ 306,260 $ 334,498 $ 952,936 $ 1,065,712 Other applications 22,878 21,848 55,018 64,111 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Sales by Product High Power Continuous Wave ("CW") Lasers $ 184,924 $ 227,462 $ 577,354 $ 724,111 Medium and Low Power CW Lasers 11,891 19,101 42,904 75,472 Pulsed Lasers 33,850 35,408 106,100 115,243 Quasi-Continuous Wave ("QCW") Lasers 12,479 18,276 42,612 54,568 Laser and Non-Laser Systems 32,929 14,701 104,943 37,600 Other Revenue including Amplifiers, Service, Parts, Accessories and Change in Deferred Revenue 53,065 41,398 134,041 122,829 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Sales by Geography North America $ 71,000 $ 53,762 $ 199,947 $ 140,704 Europe: Germany 17,204 21,714 59,487 86,939 Other including Eastern Europe/CIS 62,196 66,392 192,527 225,717 Asia and Australia: China 121,290 158,853 399,246 511,852 Japan 21,859 21,871 54,879 60,927 Other 28,877 31,953 89,544 99,476 Rest of World 6,712 1,801 12,324 4,208 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823 Timing of Revenue Recognition Goods and services transferred at a point in time $ 310,324 $ 355,191 $ 944,454 $ 1,126,285 Goods and services transferred over time 18,814 1,155 63,500 3,538 Total $ 329,138 $ 356,346 $ 1,007,954 $ 1,129,823
Changes in Contract Liabilities	The following table reflects the changes in the Company's contract assets and liabilities for the nine months ended September 30, 2019 and 2018: September 30, January 1, September 30, January 1, 2019 2019 Change 2018 2018 Change Contract assets Contract assets $ 10,606 $ 10,102 $ 504 $ — $ — $ — Contract liabilities Contract liabilities - current 49,358 52,606 (3,248) 48,274 46,508 1,766 Contract liabilities - long-term 1,677 1,413 264 1,374 182 1,192
Schedule of Remaining Performance Obligations	The following table represents the Company's remaining performance obligations from contracts that are recognized over time as of September 30, 2019: Remaining Performance Obligations 2019 (a) 2020 2021 2022 2023 2024 and thereafter Total Revenue expected to be recognized for extended warranty agreements $ 1,432 $ 3,395 $ 545 $ 297 $ 120 $ 14 $ 5,803 Revenue to be earned over time from contracts to sell robotic systems 16,061 6,659 — — — — 22,720 Total $ 17,493 $ 10,054 $ 545 $ 297 $ 120 $ 14 $ 28,523 (a) For the three-month period beginning October 1, 2019.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Assets And Liabilities Measured At Fair Value	The following table presents fair value information related to the Company's assets and liabilities measured at amortized cost on the condensed consolidated balance sheets with the exception of the interest rate swap, which is measured at fair value: Fair Value Measurements at September 30, 2019 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market fund deposits and term deposits $ 123,243 $ 123,243 $ — $ — Commercial paper 56,831 — 56,831 — Short-term investments: U.S. Treasury and agency obligations 20,971 20,971 — — Corporate bonds 270,911 270,911 — — Non-U.S. government bonds 3,000 — 3,000 — Commercial paper 197,453 — 197,453 — Certificate of deposit 6,498 6,498 — — Long-term investments and other assets: Auction rate securities 590 — — 590 Interest rate swap 32 — 32 — Total $ 679,529 $ 421,623 $ 257,316 $ 590 Liabilities Long-term debt $ 42,631 $ — $ 42,631 $ — Contingent purchase consideration 297 — — 297 Total $ 42,928 $ — $ 42,631 $ 297 Fair Value Measurements at December 31, 2018 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market fund deposits and term deposits $ 180,965 $ 180,965 $ — $ — U.S. Treasury and agency obligations 6,495 6,495 — — Commercial paper 78,948 — 78,948 — Short-term investments: U.S. Treasury and agency obligations 116,800 116,800 — — Corporate bonds 227,009 227,009 — — Commercial paper 156,321 — 156,321 — Long-term investments and other assets: Corporate bonds 3,859 3,859 — — Auction rate securities 847 — — 847 Interest rate swaps 31 — 31 — Total $ 771,275 $ 535,128 $ 235,300 $ 847 Liabilities Long-term debt $ 45,378 $ — $ 45,378 $ — Contingent purchase consideration 898 — — 898 Total $ 46,276 $ — $ 45,378 $ 898
Fair Value, Assets Measured on Recurring Basis	The following table presents information about the Company's movement in Level 3 assets and liabilities measured at fair value: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Auction rate securities Balance, beginning of period $ 852 $ 1,174 $ 847 $ 1,016 Redemptions (264) (207) (264) (207) Change in fair value and accretion 2 — 7 158 Balance, end of period $ 590 $ 967 $ 590 $ 967 Contingent purchase consideration Balance, beginning of period $ 300 $ 902 $ 898 $ 902 Cash payments — — (632) — Foreign exchange adjustment (3) — 31 — Balance, end of period $ 297 $ 902 $ 297 $ 902
Fair Value, Liabilities Measured on Recurring Basis	The following table presents information about the Company's movement in Level 3 assets and liabilities measured at fair value: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Auction rate securities Balance, beginning of period $ 852 $ 1,174 $ 847 $ 1,016 Redemptions (264) (207) (264) (207) Change in fair value and accretion 2 — 7 158 Balance, end of period $ 590 $ 967 $ 590 $ 967 Contingent purchase consideration Balance, beginning of period $ 300 $ 902 $ 898 $ 902 Cash payments — — (632) — Foreign exchange adjustment (3) — 31 — Balance, end of period $ 297 $ 902 $ 297 $ 902
Schedule of Effective Maturity Dates of Held To Maturity Investments	The following table presents the effective maturity dates of held-to-maturity and available-for-sale debt investments as of September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 Book Value Fair Value Book Value Fair Value Investment maturity Held-to-maturity: Less than 1 year $ 498,508 $ 498,833 $ 585,875 $ 585,573 1 through 5 years — — 3,859 3,859 Total $ 498,508 $ 498,833 $ 589,734 $ 589,432 Available-for-sale: Greater than 5 years $ 590 $ 590 $ 847 $ 847

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Components of Inventories	Inventories consist of the following: September 30, December 31, 2019 2018 Components and raw materials $ 235,276 $ 233,594 Work-in-process 49,744 66,498 Finished components and devices 132,143 103,487 Total $ 417,163 $ 403,579

Goodwill And Intangibles (Table

Goodwill And Intangibles (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table sets forth the changes in the carrying amount of goodwill for the nine months ended September 30, 2019: Amount Balance at January 1 $ 100,722 Goodwill arising from acquisition 9,426 Adjustment to goodwill during measurement period 448 Foreign exchange adjustment (642) Balance at September 30 $ 109,954
Schedule of Intangible Assets	Intangible assets, subject to amortization, consisted of the following: September 30, 2019 December 31, 2018 Gross Carrying Accumulated Net Carrying Weighted- Average Lives Gross Carrying Accumulated Net Carrying Weighted- Customer relationships $ 62,241 $ (10,963) $ 51,278 10 years $ 57,849 $ (6,427) $ 51,422 11 years Technology, trademark and tradename 41,350 (14,779) 26,571 7 years 41,184 (10,474) 30,710 7 years Production know-how 13,581 (7,469) 6,112 7 years 9,211 (6,212) 2,999 7 years Patents 8,036 (6,436) 1,600 8 years 8,036 (6,028) 2,008 8 years Total $ 125,208 $ (39,647) $ 85,561 $ 116,280 $ (29,141) $ 87,139
Estimated Future Amortization Expense For Intangibles	The estimated future amortization expense for intangibles for the remainder of 2019 and subsequent years is as follows: 2019 (a) 2020 2021 2022 2023 Thereafter Total $ 3,586 $ 13,562 13,197 $ 12,280 $ 11,350 $ 31,586 $ 85,561 (a) For the three-month period beginning October 1, 2019.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Summary of Lease Assets and Liabilities	The Company's operating lease assets and lease liabilities consist of the following as of September 30, 2019: Account Classification Amount Right-of-use assets Other assets $ 26,304 Short-term lease liabilities Accrued expenses and other liabilities 5,315 Long-term lease liabilities Deferred income taxes and other long-term liabilities 21,153 Total lease liabilities $ 26,468
Schedule of Operating Lease Maturities	The table below presents the future minimum lease payments to be made under non-cancelable operating leases as of December 31, 2018: Years ending December 31, 2019 $ 6,314 2020 4,603 2021 3,358 2022 2,596 2023 2,078 Thereafter 11,340 Total $ 30,289 The table below presents the maturities of operating lease liabilities as of September 30, 2019: 2019 (a) $ 1,617 2020 5,683 2021 4,562 2022 3,452 2023 2,880 Thereafter 12,472 Total future minimum lease payments 30,666 Less: imputed interest (4,198) Present value of lease liabilities $ 26,468 (a) For the three-month period beginning October 1, 2019.
Schedule of Lease Information	Other information relevant to the Company's operating leases consist of the following as of September 30, 2019: Weighted-average remaining lease term 9 years Weighted-average discount rate 3.61 %

Accrued Expenses And Other Li_2

Accrued Expenses And Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Components of Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consist of the following: September 30, December 31, 2019 2018 Accrued compensation $ 57,939 $ 60,107 Contract liabilities 49,358 52,606 Current portion of accrued warranty 23,802 23,106 Short-term lease liabilities 5,315 — Other 15,017 18,821 Total $ 151,431 $ 154,640

Product Warranties (Tables)

Product Warranties (Tables)	9 Months Ended
	Sep. 30, 2019
Product Warranties Disclosures [Abstract]
Summary of Product Warranty Activity	The following table summarizes product warranty accrual activity recorded during the nine months ended September 30, 2019 and 2018. 2019 2018 Balance at January 1 $ 51,422 $ 47,517 Provision for warranty accrual 16,916 19,050 Warranty claims (17,399) (13,827) Foreign currency translation (1,077) (1,057) Balance at September 30 $ 49,862 $ 51,683

Financing Arrangements (Tables)

Financing Arrangements (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Borrowings Under Existing Financing Arrangements	The Company's borrowings under existing financing arrangements consist of the following: September 30, December 31, 2019 2018 Long-term notes $ 42,631 $ 45,378 Less: current portion (3,722) (3,671) Total long-term debt $ 38,909 $ 41,707

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivatives	The fair value amounts in the condensed consolidated balance sheets were: Notional Amounts (1) Other Assets September 30, December 31, September 30, December 31, 2019 2018 2019 2018 $ 19,891 $ 20,781 $ 32 $ 31 (1) Notional amounts represent the gross contract/notional amount of the derivatives outstanding.
Derivative Gains (Losses) In The Consolidated Statements Of Income Related To Interest Rate Swap Contracts	The derivative gains and losses in the condensed consolidated financial statements for the three and nine months ended September 30, 2019 and 2018, related to the Company's current and previous interest rate swap contracts were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Effective portion recognized in other comprehensive income, pretax: Interest rate swap $ 4 $ (5) $ 1 $ (3)

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Unrecognized Tax Benefits	The following is a summary of the activity of the Company’s unrecognized tax benefits for nine months ended September 30, 2019 and 2018: 2019 2018 Balance at January 1, $ 11,206 $ 10,370 Change in prior period positions — (1,067) Additions for tax positions in current period 3,342 1,012 Foreign currency translation (84) (771) Balance at September 30, $ 14,464 $ 9,544

Net Income Attributable To IP_2

Net Income Attributable To IPG Photonics Corporation Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Computation of Diluted Net Income Per Share	The following table sets forth the computation of diluted net income attributable to IPG Photonics Corporation per share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net income attributable to IPG Photonics Corporation $ 57,253 $ 100,517 $ 184,684 $ 328,468 Net income attributable to common stockholders 57,253 100,517 184,684 328,468 Weighted average shares 52,928 53,571 53,073 53,677 Dilutive effect of common stock equivalents 694 1,125 791 1,318 Diluted weighted average common shares 53,622 54,696 53,864 54,995 Basic net income attributable to IPG Photonics Corporation per share $ 1.08 $ 1.88 $ 3.48 $ 6.12 Basic net income attributable to common stockholders $ 1.08 $ 1.88 $ 3.48 $ 6.12 Diluted net income attributable to IPG Photonics Corporation per share $ 1.07 $ 1.84 $ 3.43 $ 5.97 Diluted net income attributable to common stockholders $ 1.07 $ 1.84 $ 3.43 $ 5.97

Recent Accounting Pronounceme_4

Recent Accounting Pronouncements (Cumulative Effect of Changes to Balance Sheet) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	$ 65,896	$ 57,440	$ 57,764
Other assets	50,321	38,395	18,932
Accrued expenses and other current liabilities	151,431	159,932	154,640
Deferred income taxes and other long-term liabilities	$ 105,772	94,581	$ 80,734
ASC 842
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets		(324)
Other assets		19,463
Accrued expenses and other current liabilities		5,292
Deferred income taxes and other long-term liabilities		$ 13,847

Recent Accounting Pronounceme_5

Recent Accounting Pronouncements (Schedule of Cash, Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 580,329	$ 544,358
Restricted cash included in other assets	2,789
Cash, cash equivalents and restricted cash	$ 583,118	$ 544,358	$ 647,606	$ 909,900

Revenue From Contracts With C_3

Revenue From Contracts With Customers (Disaggregation of Revenue, By Application) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Sales by Application
Total	$ 329,138	$ 356,346	$ 1,007,954	$ 1,129,823
Materials processing
Sales by Application
Total	306,260	334,498	952,936	1,065,712
Other applications
Sales by Application
Total	$ 22,878	$ 21,848	$ 55,018	$ 64,111

Revenue From Contracts With C_4

Revenue From Contracts With Customers (Disaggregation of Revenue, By Product) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total	$ 329,138	$ 356,346	$ 1,007,954	$ 1,129,823
High Power Continuous Wave ("CW") Lasers
Disaggregation of Revenue [Line Items]
Total	184,924	227,462	577,354	724,111
Medium and Low Power CW Lasers
Disaggregation of Revenue [Line Items]
Total	11,891	19,101	42,904	75,472
Pulsed Lasers
Disaggregation of Revenue [Line Items]
Total	33,850	35,408	106,100	115,243
Quasi-Continuous Wave ("QCW") Lasers
Disaggregation of Revenue [Line Items]
Total	12,479	18,276	42,612	54,568
Laser and Non-Laser Systems
Disaggregation of Revenue [Line Items]
Total	32,929	14,701	104,943	37,600
Other Revenue including Amplifiers, Service, Parts, Accessories and Change in Deferred Revenue
Disaggregation of Revenue [Line Items]
Total	$ 53,065	$ 41,398	$ 134,041	$ 122,829

Revenue From Contracts With C_5

Revenue From Contracts With Customers (Disaggregation of Revenue, By Geography) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Sales by Geography
Total	$ 329,138	$ 356,346	$ 1,007,954	$ 1,129,823
North America
Sales by Geography
Total	71,000	53,762	199,947	140,704
Germany
Sales by Geography
Total	17,204	21,714	59,487	86,939
Other including Eastern Europe/CIS
Sales by Geography
Total	62,196	66,392	192,527	225,717
China
Sales by Geography
Total	121,290	158,853	399,246	511,852
Japan
Sales by Geography
Total	21,859	21,871	54,879	60,927
Other
Sales by Geography
Total	28,877	31,953	89,544	99,476
Rest of World
Sales by Geography
Total	$ 6,712	$ 1,801	$ 12,324	$ 4,208

Revenue From Contracts With C_6

Revenue From Contracts With Customers (Disaggregation of Revenue, By Timing) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Timing of Revenue Recognition
Total	$ 329,138	$ 356,346	$ 1,007,954	$ 1,129,823
Goods and services transferred at a point in time
Timing of Revenue Recognition
Total	310,324	355,191	944,454	1,126,285
Goods and services transferred over time
Timing of Revenue Recognition
Total	$ 18,814	$ 1,155	$ 63,500	$ 3,538

Revenue From Contracts With C_7

Revenue From Contracts With Customers (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Concentration Risk [Line Items]
Revenue recognized that was included in the contract liability balance at the beginning of the period	$ 4,534	$ 3,355	$ 40,786	$ 38,885
One Customer | Customer Concentration Risk | Revenue from Contract with Customer
Concentration Risk [Line Items]
Concentration risk, percentage			9.00%	13.00%
One Customer | Customer Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage			29.00%		25.00%

Revenue From Contracts With C_8

Revenue From Contracts With Customers (Changes in Contract Assets and Contract Liabilities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Contract assets
Contract assets	$ 10,606	$ 0	$ 10,102	$ 0
Contract assets, change	504	0
Contract liabilities
Contract liabilities - current	49,358	48,274	52,606	46,508
Contract liabilities - current, change	(3,248)	1,766
Contract liabilities - long-term	1,677	1,374	$ 1,413	$ 182
Contract liabilities - long-term, change	$ 264	$ 1,192

Revenue From Contracts With C_9

Revenue From Contracts With Customers (Schedule of Remaining Performance Obligations) (Details) $ in Thousands	Sep. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 17,493
Remaining performance obligations, expected timing	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 1,432
Remaining performance obligations, expected timing	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 16,061
Remaining performance obligations, expected timing	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 10,054
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 3,395
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 6,659
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 545
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 545
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 0
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 297
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 297
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 0
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 120
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 120
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 0
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 14
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 14
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 0
Remaining performance obligations, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 28,523
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Revenue expected to be recognized for extended warranty agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	5,803
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Revenue to be earned over time from contracts to sell robotic systems
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 22,720

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilities Measured At Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Total	$ 679,529	$ 771,275
Liabilities
Long-term debt	42,631	45,378
Contingent purchase consideration	297	898
Total	42,928	46,276
Level 1
Assets
Total	421,623	535,128
Liabilities
Long-term debt	0	0
Contingent purchase consideration	0	0
Total	0	0
Level 2
Assets
Total	257,316	235,300
Liabilities
Long-term debt	42,631	45,378
Contingent purchase consideration	0	0
Total	42,631	45,378
Level 3
Assets
Total	590	847
Liabilities
Long-term debt	0	0
Contingent purchase consideration	297	898
Total	297	898
Money market fund deposits and term deposits
Assets
Cash equivalents	123,243	180,965
Money market fund deposits and term deposits | Level 1
Assets
Cash equivalents	123,243	180,965
Money market fund deposits and term deposits | Level 2
Assets
Cash equivalents	0	0
Money market fund deposits and term deposits | Level 3
Assets
Cash equivalents	0	0
Commercial paper
Assets
Cash equivalents	56,831	78,948
Commercial paper | Level 1
Assets
Cash equivalents	0	0
Commercial paper | Level 2
Assets
Cash equivalents	56,831	78,948
Commercial paper | Level 3
Assets
Cash equivalents	0	0
U.S. Treasury and agency obligations
Assets
Cash equivalents		6,495
Short-term investments	20,971	116,800
U.S. Treasury and agency obligations | Level 1
Assets
Cash equivalents		6,495
Short-term investments	20,971	116,800
U.S. Treasury and agency obligations | Level 2
Assets
Cash equivalents		0
Short-term investments	0	0
U.S. Treasury and agency obligations | Level 3
Assets
Cash equivalents		0
Short-term investments	0	0
Corporate bonds
Assets
Short-term investments	270,911	227,009
Long-term investments and other assets		3,859
Corporate bonds | Level 1
Assets
Short-term investments	270,911	227,009
Long-term investments and other assets		3,859
Corporate bonds | Level 2
Assets
Short-term investments	0	0
Long-term investments and other assets		0
Corporate bonds | Level 3
Assets
Short-term investments	0	0
Long-term investments and other assets		0
Non-U.S. government bonds
Assets
Short-term investments	3,000
Non-U.S. government bonds | Level 1
Assets
Short-term investments	0
Non-U.S. government bonds | Level 2
Assets
Short-term investments	3,000
Non-U.S. government bonds | Level 3
Assets
Short-term investments	0
Commercial paper, not included in cash equivalents
Assets
Short-term investments	197,453	156,321
Commercial paper, not included in cash equivalents | Level 1
Assets
Short-term investments	0	0
Commercial paper, not included in cash equivalents | Level 2
Assets
Short-term investments	197,453	156,321
Commercial paper, not included in cash equivalents | Level 3
Assets
Short-term investments	0	0
Certificate of deposit
Assets
Short-term investments	6,498
Certificate of deposit | Level 1
Assets
Short-term investments	6,498
Certificate of deposit | Level 2
Assets
Short-term investments	0
Certificate of deposit | Level 3
Assets
Short-term investments	0
Auction rate securities
Assets
Long-term investments and other assets	590	847
Auction rate securities | Level 1
Assets
Long-term investments and other assets	0	0
Auction rate securities | Level 2
Assets
Long-term investments and other assets	0	0
Auction rate securities | Level 3
Assets
Long-term investments and other assets	590	847
Interest rate swap
Assets
Long-term investments and other assets	32	31
Interest rate swap | Level 1
Assets
Long-term investments and other assets	0	0
Interest rate swap | Level 2
Assets
Long-term investments and other assets	32	31
Interest rate swap | Level 3
Assets
Long-term investments and other assets	$ 0	$ 0

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value	$ 679,529,000	$ 771,275,000
Held-to-maturity Securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value	498,833,000	500,130,000
Unrealized gain (loss)	325,000	(302,000)
Held-to-maturity Securities | Long-Term Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value	0	3,859,000
Available-for-sale Securities | Auction rate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, cost basis	$ 590,000	$ 847,000

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Auction Rate Securities and Contingent Purchase Consideration) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Auction rate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 852	$ 1,174	$ 847	$ 1,016
Redemptions	(264)	(207)	(264)	(207)
Change in fair value and accretion	2	0	7	158
Balance, end of period	590	967	590	967
Contingent purchase consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	300	902	898	902
Cash payments	0	0	(632)	0
Foreign exchange adjustment	(3)	0	31	0
Balance, end of period	$ 297	$ 902	$ 297	$ 902

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Effective Maturity Dates of Held To Maturity Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investment maturity
Held-to-maturity maturities, Less than 1 year, Book Value	$ 498,508	$ 585,875
Held-to-maturity maturities, 1 through 5 years, Book Value	0	3,859
Held-to-maturity maturities, Total Book Value	498,508	589,734
Held-to-maturity maturities, Less than 1 year, Fair Value	498,833	585,573
Held-to-maturity maturities, 1 through 5 years, Fair Value	0	3,859
Held-to-maturity maturities, Total Fair Value	498,833	589,432
Available-for-sale maturity, Greater than 5 years, Book Value	590	847
Available-for-sale maturity, Greater than 5 years, Fair Value	$ 590	$ 847

Inventories (Components Of Inve

Inventories (Components Of Inventories) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Components and raw materials	$ 235,276	$ 233,594
Work-in-process	49,744	66,498
Finished components and devices	132,143	103,487
Total	$ 417,163	$ 403,579

Inventories (Narrative) (Detail

Inventories (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventory provisions	$ 7,303	$ 3,076	$ 19,952	$ 9,930

Goodwill And Intangibles (Sched

Goodwill And Intangibles (Schedule of Changes) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Goodwill [Roll Forward]
Balance at January 1	$ 100,722
Goodwill arising from acquisition	9,426
Adjustment to goodwill during measurement period	448
Foreign exchange adjustment	(642)
Balance at September 30	$ 109,954

Goodwill And Intangibles (Narra

Goodwill And Intangibles (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Restricted cash	$ 2,789			$ 2,789
Goodwill arising from acquisition				9,426
Amortization expense	3,617		$ 1,982	10,581	$ 5,821
Genesis Systems Group
Business Acquisition [Line Items]
Percentage of business acquired						100.00%
Working capital adjustment		$ 448
Padtec SA, Submarine Networks Division
Business Acquisition [Line Items]
Purchase price		19,560
Restricted cash	2,789	2,934		2,789
Goodwill arising from acquisition		9,426
Licenses | Padtec SA, Submarine Networks Division
Business Acquisition [Line Items]
Restricted cash	$ 1,801	1,956		$ 1,801
Production know-how | Padtec SA, Submarine Networks Division
Business Acquisition [Line Items]
Acquired finite-lived intangible assets		$ 4,825
Weighted average useful life of acquired intangible assets		6 years
Customer relationships | Padtec SA, Submarine Networks Division
Business Acquisition [Line Items]
Acquired finite-lived intangible assets		$ 4,825
Weighted average useful life of acquired intangible assets		6 years

Goodwill And Intangibles (Intan

Goodwill And Intangibles (Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 125,208	$ 116,280
Accumulated Amortization	(39,647)	(29,141)
Net  Carrying Amount	85,561	87,139
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	62,241	57,849
Accumulated Amortization	(10,963)	(6,427)
Net  Carrying Amount	$ 51,278	$ 51,422
Weighted- Average  Lives	10 years	11 years
Technology, trademark and tradename
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 41,350	$ 41,184
Accumulated Amortization	(14,779)	(10,474)
Net  Carrying Amount	$ 26,571	$ 30,710
Weighted- Average  Lives	7 years	7 years
Production know-how
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 13,581	$ 9,211
Accumulated Amortization	(7,469)	(6,212)
Net  Carrying Amount	$ 6,112	$ 2,999
Weighted- Average  Lives	7 years	7 years
Patents
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 8,036	$ 8,036
Accumulated Amortization	(6,436)	(6,028)
Net  Carrying Amount	$ 1,600	$ 2,008
Weighted- Average  Lives	8 years	8 years

Goodwill And Intangibles (Estim

Goodwill And Intangibles (Estimated Future Amortization Expense For Intangibles) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
2019	$ 3,586
2020	13,562
2021	13,197
2022	12,280
2023	11,350
Thereafter	31,586
Net  Carrying Amount	$ 85,561	$ 87,139

Leases (Narrative) (Details)

Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 2,168	$ 6,632
Operating lease payments	$ (1,679)	$ (5,121)
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term		1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term		46 years

Leases (Lease Assets and Lease

Leases (Lease Assets and Lease Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets	$ 26,304
Short-term lease liabilities	5,315	$ 0
Long-term lease liabilities	21,153
Total lease liabilities	$ 26,468

Leases (Operating Lease Maturit

Leases (Operating Lease Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019		$ 6,314
2020		4,603
2021		3,358
2022		2,596
2023		2,078
Thereafter		11,340
Total		$ 30,289
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 1,617
2020	5,683
2021	4,562
2022	3,452
2023	2,880
Thereafter	12,472
Total future minimum lease payments	30,666
Less: imputed interest	(4,198)
Present value of lease liabilities	$ 26,468

Leases (Lease Term and Discount

Leases (Lease Term and Discount Rate) (Details)	Sep. 30, 2019
Leases [Abstract]
Weighted-average remaining lease term	9 years
Weighted-average discount rate	3.61%

Accrued Expenses And Other Li_3

Accrued Expenses And Other Liabilities (Components Of Accrued Expenses And Other Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued compensation	$ 57,939		$ 60,107
Contract liabilities	49,358		52,606	$ 48,274	$ 46,508
Current portion of accrued warranty	23,802		23,106
Short-term lease liabilities	5,315		0
Other	15,017		18,821
Total	$ 151,431	$ 159,932	$ 154,640

Product Warranties (Narrative)

Product Warranties (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Accrued warranty reported in accrued expenses and other liabilities	$ 23,802	$ 23,106
Accrued warranty reported in other long-term liabilities	$ 26,060	$ 28,316
Minimum
Product Warranty Liability [Line Items]
Service warranties on lasers and amplifiers	1 year
Maximum
Product Warranty Liability [Line Items]
Service warranties on lasers and amplifiers	3 years

Product Warranties (Summary Of

Product Warranties (Summary Of Product Warranty Activity) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at January 1	$ 51,422	$ 47,517
Provision for warranty accrual	16,916	19,050
Warranty claims	(17,399)	(13,827)
Foreign currency translation	(1,077)	(1,057)
Balance at September 30	$ 49,862	$ 51,683

Financing Arrangements (Borrowi

Financing Arrangements (Borrowings Under Existing Financing Arrangements) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Less: current portion	$ (3,722)	$ (3,671)
Total long-term debt	38,909	41,707
Long-term notes
Debt Instrument [Line Items]
Long-term notes	$ 42,631	$ 45,378

Financing Arrangements (Narrati

Financing Arrangements (Narrative) (Details) € in Thousands	9 Months Ended
	Sep. 30, 2019EUR (€)	May 31, 2023USD ($)	Jul. 31, 2022USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Total unused credit lines and overdraft facilities				$ 104,069,000
Unsecured Debt | Scenario, Forecast
Debt Instrument [Line Items]
Amount due on long-term note		$ 15,438,000
Unsecured Debt | Interest rate swap
Debt Instrument [Line Items]
Fixed interest rate swap	2.90%			2.90%
Unsecured Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	1.20%
Secured Debt
Debt Instrument [Line Items]
Amount due on long-term note				$ 22,740,000
Current portion of long-term note				$ 2,534,000
Fixed interest rate swap	2.70%			2.70%
Secured Debt | Scenario, Forecast
Debt Instrument [Line Items]
Amount due on long-term note			$ 15,375,000
Long-term notes | Unsecured Debt
Debt Instrument [Line Items]
Amount due on long-term note				$ 19,891,000
Current portion of long-term note				1,188,000
U.S. line-of-credit
Debt Instrument [Line Items]
Line of credit				0	$ 0
Guarantees issued				1,116,000	930,000
Euro line-of-credit
Debt Instrument [Line Items]
Line of credit				0	0
Guarantees issued				1,579,000	1,166,000
Euro overdraft facility
Debt Instrument [Line Items]
Line of credit				0	$ 0
Letter of Credit | U.S. line-of-credit
Debt Instrument [Line Items]
Borrowing capacity				50,000,000
Letter of Credit | Euro line-of-credit
Debt Instrument [Line Items]
Borrowing capacity	€ 50,000			54,581,000
Letter of Credit | Euro overdraft facility
Debt Instrument [Line Items]
Borrowing capacity	€ 2,000			$ 2,183,000

Derivative Financial Instrume_3

Derivative Financial Instruments (Fair Value) (Details) - Derivative designated as a cash flow hedge - Interest rate swap - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 19,891,000	$ 20,781,000
Other Assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 32,000	$ 31,000

Derivative Financial Instrume_4

Derivative Financial Instruments (Derivative Gains (Losses) In The Consolidated Statements Of Income Related To Interest Rate Swap Contracts) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion recognized in other comprehensive income, pretax	$ 4	$ (5)	$ 1	$ (3)

Commitments And Contingencies (

Commitments And Contingencies (Narrative) (Details)	Sep. 30, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Legal proceedings	$ 0

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	26.20%	21.40%		24.80%	24.20%
Discrete tax benefit	$ 5,443	$ 660		$ 8,357	$ 5,178
Discrete tax benefit, equity based compensation	229	1,026		4,271	10,920
Discrete tax benefit, provision adjustment	$ 5,326	4,247		$ 5,293	4,001
Discrete tax rate adjustment, inventory		2,195			6,584
Discrete tax rate adjustment, valuation allowance		$ 3,046			3,046
Increase in tax expense related to Global Intangible Low Taxed Income					$ 7,939
Tax Cuts and Jobs Act of 2017, income tax expense			$ 4,747

Income Taxes (Schedule of Unrec

Income Taxes (Schedule of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1,	$ 11,206	$ 10,370
Change in prior period positions	0	(1,067)
Additions for tax positions in current period	3,342	1,012
Foreign currency translation	(84)	(771)
Balance at September 30	$ 14,464	$ 9,544

Net Income Attributable To IP_3

Net Income Attributable To IPG Photonics Corporation Per Share (Computation of Diluted Net Income) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to IPG Photonics Corporation	$ 57,253	$ 100,517	$ 184,684	$ 328,468
Net income attributable to common stockholders	$ 57,253	$ 100,517	$ 184,684	$ 328,468
Weighted average shares (in shares)	52,928	53,571	53,073	53,677
Dilutive effect of common stock equivalents (in shares)	694	1,125	791	1,318
Diluted weighted average common shares (in shares)	53,622	54,696	53,864	54,995
Basic net income attributable to IPG Photonics Corporation per share (in dollars per share)	$ 1.08	$ 1.88	$ 3.48	$ 6.12
Basic net income attributable to common stockholders (in dollars per share)	1.08	1.88	3.48	6.12
Diluted net income attributable to IPG Photonics Corporation per share (in dollars per share)	1.07	1.84	3.43	5.97
Diluted net income attributable to common stockholders (in dollars per share)	$ 1.07	$ 1.84	$ 3.43	$ 5.97

Net Income Attributable to IP_4

Net Income Attributable to IPG Photonics Corporation Per Share (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Feb. 12, 2019	Jul. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded from computation of diluted weighted average common shares (in shares)	975,700	349,700	768,000	256,500
Decrease in weighted average shares outstanding, treasury stock (in shares)	125,538	119,911	48,080	177,159
2018 Program
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share repurchase authorized amount						$ 125,000,000
Stock repurchased during period (in shares)		371,228		585,806
Stock repurchase average price (in dollars per share)		$ 163.95		$ 191.06
2019 Program
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share repurchase authorized amount					$ 125,000,000
Stock repurchased during period (in shares)	180,620		196,000
Stock repurchase average price (in dollars per share)	$ 130.87		$ 132.25
Remaining repurchase amount	$ 99,000,000		$ 99,000,000
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)	167,200	73,600	149,200	54,800
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)	45,500	17,300	40,800	14,000
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)	763,000	258,800	578,000	187,700

Uncategorized Items - ipgp-2019

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 616,000
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	10,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 606,000