Advanced Energy Industries (AEIS) 10-K 15 Feb 18 2017 Q4 Annual report Financial data

DEI Parenthetical

DEI Parenthetical - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 13, 2018
Document Information [Line Items]
Entity Registrant Name	ADVANCED ENERGY INDUSTRIES INC
Entity Central Index Key	927,003
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q4
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float	$ 2,568,911,641
Entity Common Stock, Shares Outstanding		39,629,120

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 407,283	$ 281,953
Marketable securities	3,104	4,737
Accounts receivable, net of allowances of $1,748 and $1,943 respectively	87,429	75,667
Inventories	78,450	55,770
Income taxes receivable	1,295	1,482
Other current assets	8,129	9,324
Current assets from discontinued operations	9,535	9,401
Total current assets	595,225	438,334
Property and equipment, net	17,795	13,337
OTHER ASSETS:
Deposits and other	3,051	1,835
Goodwill	53,812	42,125
Finite-Lived Intangible Assets, Net	33,499	28,071
Deferred income tax assets	18,841	32,197
Non-current assets from discontinued operations	11,085	15,630
TOTAL ASSETS	733,308	571,529
CURRENT LIABILITIES:
Accounts payable	48,177	46,255
Income taxes payable	5,365	1,778
Accrued payroll and employee benefits	18,412	13,230
Other accrued expenses	19,913	14,590
Customer deposits	6,402	5,774
Current liabilities from discontinued operations	7,850	13,419
Total current liabilities	106,119	95,046
LONG-TERM LIABILITIES:
Deferred income tax liabilities	4,556	1,008
Uncertain tax positions	17,031	2,538
Long-term deferred revenue	33,402	39,170
Other long-term liabilities	36,282	20,536
Non-current liabilities from discontinued operations	15,277	21,157
Total liabilities	212,667	179,455
STOCKHOLDERS' EQUITY:
Preferred stock, $0.001 par value, 1,000 shares authorized, none issued and outstanding	0	0
Common stock, $0.001 par value, 70,000 shares authorized; 39,604 and 39,712 issued and outstanding, respectively	40	40
Additional paid-in capital	184,843	203,603
Retained earnings	333,225	195,364
Accumulated other comprehensive income (loss)	2,533	(6,933)
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	520,641	392,074
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 733,308	$ 571,529

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets Parenthetical - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable, Current	$ 1,748	$ 1,943
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,000	1,000
Preferred stock, $0.001 par value, 1,000 shares authorized, none issued and outstanding	$ 0	$ 0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	70,000,000	70,000,000
Common stock, shares issued (in shares)	39,604,000	39,712,000
Common stock, shares outstanding (in shares)	39,604,000	39,712,000

Consolidated Statement of Opera

Consolidated Statement of Operations Statement - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sales Revenue, Goods, Net	$ 578,650	$ 410,580	$ 350,834
Sales Revenue, Services, Net	92,362	73,124	63,977
Total sales	671,012	483,704	414,811
Cost of Goods Sold	267,587	192,694	164,889
Cost of Services	47,044	37,863	33,052
Total cost of sales	314,631	230,557	197,941
Gross profit	356,381	253,147	216,870
Research and development	57,999	44,445	39,551
Selling, general and administrative	93,262	77,678	66,097
Amortization of intangible assets	4,350	4,167	4,368
Restructuring expense	0	0	198
Total operating expenses	155,611	126,290	110,214
Operating income	200,770	126,857	106,656
Other income (expense), net	(2,579)	1,219	(1,214)
Income from continuing operations before income taxes	198,191	128,076	105,442
Provision for income taxes	62,090	11,128	21,960
Income from continuing operations	136,101	116,948	83,482
Income (loss) from discontinued operations, net of income taxes	1,760	10,506	(241,968)
Net income (loss)	$ 137,861	$ 127,454	$ (158,486)
Basic weighted-average common shares outstanding	39,754	39,720	40,746
Diluted weighted-average common shares outstanding	40,176	40,031	41,077
Income (Loss) from Continuing Operations, Per Basic Share	$ 3.42	$ 2.94	$ 2.05
Income (Loss) from Continuing Operations, Per Diluted Share	3.39	2.92	2.03
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0.04	0.26	(5.94)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.04	0.26	(5.94)
Basic earnings (loss) per share	3.47	3.21	(3.89)
Diluted earnings (loss) per share	$ 3.43	$ 3.18	$ (3.89)

Condensed Consolidated Statemen

Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net income (loss)	$ (29,590)	$ 83,864	$ 46,052	$ 37,535	$ 44,281	$ 30,361	$ 30,531	$ 22,281	$ 137,861	$ 127,454	$ (158,486)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									8,305	(3,631)	(10,228)
Unrealized (losses) gains on marketable securities									(2)	5	(3)
Minimum retirement benefit liability adjustment									1,163	(3,841)	(11)
Comprehensive income (loss)									$ 147,327	$ 119,987	$ (168,728)

Statement of Stockholders Equit

Statement of Stockholders Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Foreign Currency Adjustment Attributable to Parent [Member]	Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]	Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Stockholders' Equity Attributable to Parent at Dec. 31, 2014	$ 474,965	$ 41	$ 237,752	$ 226,396	$ 10,249	$ 0	$ 527
Common Stock, Shares, Outstanding at Dec. 31, 2014	40,613,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ 4,121	0	4,121	0	0	0	0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	525,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	$ 3,321	0	3,321	0	0	0	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(99)	0	(99)	0	0	0	0
Foreign currency translation adjustment	(10,228)	0	0	0	(10,228)	0	0
Unrealized (losses) gains on marketable securities	(3)	0	0	0	0	(3)	0
Minimum retirement benefit liability adjustment	(11)	0	0	0	0	0	(11)
Net income (loss)	(158,486)	0	0	(158,486)	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (168,728)	0	0	(158,486)	(10,228)	(3)	(11)
Stock Repurchased and Retired During Period, Shares	(1,382,000)
Stock Repurchased and Retired During Period, Value	$ 50,000	1	49,999	0	0	0	0
Common Stock, Shares, Outstanding at Dec. 31, 2015	39,756,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 263,580	40	195,096	67,910	21	(3)	516
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ 2,175	0	2,175	0	0	0	0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	299,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	$ 6,332	0	6,332	0	0	0	0
Foreign currency translation adjustment	(3,631)	0	0	0	(3,631)	0	0
Unrealized (losses) gains on marketable securities	5	0	0	0	0	5	0
Minimum retirement benefit liability adjustment	(3,841)	0	0	0	0	0	(3,841)
Net income (loss)	127,454	0	0	127,454	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 119,987	0	0	127,454	(3,631)	5	(3,841)
Stock Repurchased and Retired During Period, Shares	(343,000)
Stock Repurchased and Retired During Period, Value	$ 0	0	0	0	0	0	0
Common Stock, Shares, Outstanding at Dec. 31, 2016	39,712,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	$ 392,074	40	203,603	195,364	(3,610)	2	(3,325)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ (1,316)	0	(1,316)	0	0	0	0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	314,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	$ 12,549	0	12,549	0	0	0	0
Foreign currency translation adjustment	8,305	0	0	0	8,305	0	0
Unrealized (losses) gains on marketable securities	(2)	0	0	0	0	(2)	0
Minimum retirement benefit liability adjustment	1,163	0	0	0	0	0	1,163
Net income (loss)	137,861	0	0	137,861	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 147,327	0	0	137,861	8,305	(2)	1,163
Stock Repurchased and Retired During Period, Shares	(422,000)
Stock Repurchased and Retired During Period, Value	$ 29,993	0	29,993	0	0	0	0
Common Stock, Shares, Outstanding at Dec. 31, 2017	39,604,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2017	$ 520,641	$ 40	$ 184,843	$ 333,225	$ 4,695	$ 0	$ (2,162)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows Statement $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Net income (loss)	$ 137,861	$ 127,454	$ (158,486)
Income (loss) from discontinued operations, net of income taxes	1,760	10,506	(241,968)
Income from continuing operations, net of income taxes	136,101	116,948	83,482
Depreciation and amortization	9,424	7,813	8,832
Stock-based compensation expense	12,549	6,332	2,810
Provision for deferred income taxes	28,765	3,570	3,498
Non-cash reserve for potential bad debts	0	0	5,967
Loss on Foreign Exchange Hedge	3,489	0	0
Net loss (gain) on disposal of assets	122	319	(1,019)
Accounts receivable	(7,497)	(21,603)	17,919
Inventories	(19,261)	(6,359)	(6,715)
Other current assets	(1,030)	(1,358)	(2,366)
Accounts payable	1,812	18,957	3,220
Other liabilities and accrued expenses	7,159	2,169	(9,500)
Income taxes	18,323	356	17,994
Net cash provided by operating activities from continuing operations	189,956	127,144	124,122
Net cash (used in) operating activities from discontinued operations	(7,255)	(7,857)	(19,413)
Net cash provided by operating activities	182,701	119,287	104,709
Purchases of marketable securities	(107)	(763)	(30,172)
Proceeds from sale of marketable securities	1,903	7,884	21,095
Acquisitions, net of cash acquired	(17,347)	0	(128)
Purchase of foreign currency hedge	(3,489)	0	0
Purchases of property and equipment	(9,042)	(6,821)	(4,014)
Net cash (used in) provided by investing activities from continuing operations	(28,082)	300	(13,219)
Net cash used in investing activities from discontinued operations	0	0	(46)
Net cash (used in) provided by investing activities	(28,082)	300	(13,265)
Purchase and retirement of common stock	(29,993)	0	(50,000)
Net (payments) proceeds related to stock based award activities	(1,315)	2,175
Net (payments) proceeds related to stock-based award activities			4,476
Other financing activities	1	(4)	(4)
Net cash (used in) provided by financing activities from continuing operations	(31,307)	2,171	(45,528)
Net cash (used in) financing activities from discontinued operations	0	(29)	(14)
Net cash (used in) provided by financing activities	(31,307)	2,142	(45,542)
EFFECT OF CURRENCY TRANSLATION ON CASH	2,208	(1,932)	(1,467)
INCREASE IN CASH AND CASH EQUIVALENTS	125,520	119,797	44,435
CASH AND CASH EQUIVALENTS, beginning of period	289,517	169,720	125,285
CASH AND CASH EQUIVALENTS, end of period	415,037	289,517	169,720
Less cash and cash equivalents from discontinued operations	7,754	7,564	11,277
Cash and cash equivalents	407,283	281,953	158,443
Cash paid for interest	66	173	361
Cash paid for income taxes	5,314	5,647	7,161
Cash received for refunds of income taxes	1,448	2,232	5,377
Cash held in banks outside the United States	$ 285,686	$ 230,168	$ 116,259

Operations and Summary of Signi

Operations and Summary of Significant Accounting Policies and Estimates	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operations And Summary Of Significant Accounting Policies [Text Block]	OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES We design, manufacture, sell and support power conversion and control products that transform power into various usable forms. Our products enable manufacturing processes that use thin film and plasma enhanced chemical and physical processing for various products, industrial electro-thermal applications for material and chemical processes, precision power for analytical instrumentation, as well as grid-tied power conversion. We also supply thermal instrumentation products for advanced temperature control in these markets. Our network of global service support centers provides local repair and field service capability in key regions. As of December 31, 2015, we discontinued our Inverter production, engineering, and sales product line. As such, all Inverter revenues, costs, assets and liabilities are reported in Discontinued Operations for all periods presented herein and we currently report as a single unit. See Note 3. Discontinued Operations for more information. Principles of Consolidation — Our Consolidated Financial Statements include our accounts and the accounts of our wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated. Our Consolidated Financial Statements are stated in United States dollars and have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Use of Estimates in the Preparation of the Consolidated Financial Statements — The preparation of our Consolidated Financial Statements in conformity with U.S. GAAP requires us to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, and disclosure of contingent liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. We believe that the significant estimates, assumptions, and judgments when accounting for items and matters such as allowances for doubtful accounts, excess and obsolete inventory, warranty reserves, acquisitions, asset valuations, asset life, depreciation, amortization, recoverability of assets, impairments, deferred revenue, stock option and restricted stock grants, taxes, and other provisions are reasonable, based upon information available at the time they are made. Actual results may differ from these estimates, making it possible that a change in these estimates could occur in the near term. Foreign Currency Translation — The functional currency of our foreign subsidiaries is their local currency, with the exception of our manufacturing facility in Shenzhen, The People's Republic of China (“PRC”) and our regional headquarters in Singapore, where the United States dollar is the functional currency. Assets and liabilities of foreign subsidiaries are translated to United States dollars at period-end exchange rates, and our Consolidated Statements of Operations and Cash Flows are translated at average exchange rates during the period. Resulting translation adjustments are recorded as a component of accumulated other comprehensive income. Transactions denominated in currencies other than the local currency are recorded based on exchange rates at the time such transactions arise. Subsequent changes in exchange rates result in foreign currency transaction gains and losses which are reflected as unrealized (based on period end translation) or realized (upon settlement of the transactions) in other income, net in our Consolidated Statements of Operations. Fair Value of Financial Instruments — We value our financial assets and liabilities using fair value measurements. Fair value is based on the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying amount of cash and cash equivalents, marketable securities, accounts receivable, other current assets, accounts payable, accrued liabilities, and other current liabilities in our Consolidated Financial Statements approximates fair value because of the short-term nature of the instruments. Cash and Cash Equivalents — We consider all amounts on deposit with financial institutions and highly liquid investments with an original maturity of three months or less to be cash equivalents. Cash and cash equivalents are highly liquid investments that consist primarily of short-term money market instruments and demand deposits with insignificant interest rate risk and original maturities of three months or less at the time of purchase. Sometimes we invest excess cash in money market funds not insured by the Federal Deposit Insurance Corporation. We believe that the investments in money market funds are on deposit with credit-worthy financial institutions and that the funds are highly liquid. The investments in money market funds are reported at fair value, with interest income recorded in earnings and are included in “Cash and cash equivalents.” The fair values of our investments in money market funds are based on the quoted market prices. As of December 31, 2017 we have $1.2 million of cash included in cash and cash equivalents that is restricted from immediate withdrawal. Of this amount, $0.5 million is a refund from a European tax authority, restricted until the tax authority completes its audit procedures, $0.2 million is restricted for China and Taiwan Customs Clearance transactions as a guarantee of Customs Duty, adjusted annually based on projected customs clearance transactions, and $0.5 million is collateral for the U.S. purchasing card program, restricted for the duration of the card program. Marketable Securities — All of our investments in marketable securities are classified as available-for-sale at the respective balance sheet dates. Marketable securities classified as available-for-sale are recorded at fair value based upon quoted market prices, and any temporary difference between the cost and fair value of the investment is presented as a separate component of accumulated other comprehensive income (loss). We recognize gains and losses on the date our investments mature or are sold and record these gains and losses in other income, net. The specific identification method is used to determine the gains and losses on investments in marketable securities. Concentrations of Credit Risk — Financial instruments, which potentially subject us to credit risk, include cash and cash equivalents, marketable securities, and trade accounts receivable. To preserve capital and maintain liquidity, we invest with financial institutions we deem to be of high quality and sound financial condition. Our investments are in low-risk instruments and we limit our credit exposure in any one institution or type of investment instrument based upon criteria including creditworthiness. At December 31, 2017 , our accounts receivable from Applied Materials and Lam Research were $36.8 million , or 42.0% and $5.4 million , or 6.2% of our total accounts receivable, respectively. At December 31, 2016 , our accounts receivable from Applied Materials and Lam Research were $31.1 million , or 41.1% and $14.3 million , or 18.9% of our total accounts receivable, respectively. No other customer balance exceeded 10% of our total accounts receivable balance at December 31, 2017 or December 31, 2016 . We have established an allowance for doubtful accounts based upon factors surrounding the credit risk of specific customers, historical trends, and other information. Accounts Receivable and Allowance for Doubtful Accounts — Accounts receivable are recorded at net realizable value. We maintain a credit approval process and we make significant judgments in connection with assessing our customers’ ability to pay at the time of shipment. Despite this assessment, from time to time, our customers are unable to meet their payment obligations. We continuously monitor our customers’ credit worthiness and use our judgment in establishing a provision for estimated credit losses based upon our historical experience and any specific customer collection issues that we have identified. While such credit losses have historically been within our expectations and the provisions established, there is no assurance that we will continue to experience the same credit loss rates that we have in the past. A significant change in the liquidity or financial position of our customers could have a material adverse impact on the collectability of accounts receivable and our future operating results. Changes in allowance for doubtful accounts are summarized as follows: Years Ended December 31, 2017 2016 2015 Balances at beginning of period $ 1,943 $ 8,739 $ 1,052 Additions - charged to expense — 1,332 7,837 Deductions - write-offs, net of recoveries (195 ) (8,128 ) (150 ) Balances at end of period $ 1,748 $ 1,943 $ 8,739 Inventories — Inventories include costs of materials, direct labor, manufacturing overhead, in-bound freight, and duty. Inventories are valued at the lower of cost (first-in, first-out method) or market and are presented net of reserves for excess and obsolete inventory. We regularly review inventory quantities on hand and record a provision to write-down excess and obsolete inventory to its estimated net realizable value, if less than cost, based primarily on historical usage and our estimated forecast of product demand. Demand for our products can fluctuate significantly. A significant decrease in demand could result in an increase in the charges for excess inventory quantities on hand. In addition, our industry is subject to technological change, new product development, and product technological obsolescence that could result in an increase in the amount of obsolete inventory quantities on hand. Therefore, any significant unanticipated changes in demand or technological developments could have a significant impact on the value of our inventory and our reported operating results. Property and Equipment — Property and equipment is stated at cost or estimated fair value if acquired in a business combination. Depreciation is computed over the estimated useful lives using the straight-line method. Estimated useful lives for financial reporting purposes are as follows: buildings, 20 to 40 years; machinery, equipment, furniture and fixtures and vehicles, three to 10 years; and computer and communication equipment, three years. Amortization of leasehold improvements and leased equipment is calculated using the straight-line method over the lease term or the estimated useful life of the assets, whichever period is shorter. Leasehold additions and improvements are capitalized, while maintenance and repairs are expensed as incurred. When depreciable assets are retired, or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any related gains or losses are included in other income, net, in our Consolidated Statements of Operations. Intangible Assets, Goodwill and Other Long-Lived Assets — As a result of our acquisitions, we identified and recorded intangible assets and goodwill. Intangible assets are valued based on estimates of future cash flows and amortized over their estimated useful lives. Goodwill is subject to annual impairment testing, as well as testing upon the occurrence of any event that indicates a potential impairment. Intangible assets and other long-lived assets are subject to an impairment test if there is an indicator of impairment. The carrying value and ultimate realization of these assets is dependent upon our estimates of future earnings and benefits that we expect to generate from their use. If our expectations of future results and cash flows are significantly diminished, intangible assets and goodwill may be impaired and the resulting charge to operations may be material. When we determine that the carrying value of intangibles or other long-lived assets may not be recoverable based upon the existence of one or more indicators of impairment, we use the projected undiscounted cash flow method to determine whether an impairment exists, and then measure the impairment using discounted cash flows. The estimation of useful lives and expected cash flows requires us to make significant judgments regarding future periods that are subject to some factors outside of our control. Changes in these estimates can result in significant revisions to our carrying value of these assets and may result in material charges to our results of operations. The annual impairment test for goodwill can be performed using an assessment of qualitative factors in determining if it is more likely than not that goodwill is impaired. If this assessment indicates that it is more likely than not that goodwill is impaired, the next step of impairment testing compares the fair value of a reporting unit to its carrying value. Goodwill would be impaired if the resulting implied fair value of goodwill was less than the recorded carrying value of the goodwill. Revenue Recognition — We recognize revenue from product sales upon transfer of title and risk of loss to our customers provided that there is evidence of an arrangement, the sales price is fixed or determinable, and the collection of the related receivable is reasonably assured. In most transactions, we have no obligations to our customers after the date products are shipped, other than pursuant to warranty obligations. Shipping and handling fees billed to customers, if any, are recognized as revenue. The related shipping and handling costs are recognized in cost of sales. We maintain a worldwide support organization in nine countries, including the United States, the PRC, Japan, Korea, Taiwan, Canada, Germany, Ireland and Great Britain. Support services include warranty and non-warranty repair services, upgrades, and refurbishments on the products we sell. Repairs that are covered under our standard warranty do not generate revenue. As part of our ongoing service business, we satisfy our service obligations under extended warranties and preventive maintenance contracts. Extended warranties had previously been offered on our discontinued inverter products. Any up-front fees received for extended warranties or maintenance plans are deferred and recognized ratably over the service periods, as defined in the agreements. We have deferred revenue related to our extended warranties and service contracts totaling $37.5 million as of December 31, 2017 and $40.8 million as of December 31, 2016 . Research and Development Expenses — Costs incurred to advance, test or otherwise modify our proprietary technology or develop new technologies are considered research and development costs and are expensed when incurred. These costs are primarily comprised of costs associated with the operation of our laboratories and research facilities, including internal labor, materials, and overhead. Warranty Costs — We provide for the estimated costs to fulfill customer warranty obligations upon the recognition of the related revenue. We offer warranty coverage for a majority of our Precision Power products for periods typically ranging from 12 to 24 months after shipment. We warranted our inverter products for five to ten years and provided the option to purchase additional warranty coverage for up to 20 years. The warranty expense accrued related to our standard inverter product warranties is now considered part of our discontinued operations and is recorded as such on our Consolidated Balance Sheets. See Note 3. Discontinued Operations for more information. See Note 12. Warranties for more information on our warranties from continuing operations. We estimate the anticipated costs of repairing our products under such warranties based on the historical costs of the repairs. The assumptions we use to estimate warranty accruals are reevaluated periodically, in light of actual experience, and when appropriate, the accruals are adjusted. Should product failure rates differ from our estimates, actual costs could vary significantly from our expectations. Stock-Based Compensation — Accounting for stock-based compensation requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and directors based on estimated fair values. We have estimated the fair value of all stock options and awards on the date of grant using the Black-Scholes-Merton pricing model, which is affected by our stock price, as well as assumptions regarding a number of complex and subjective variables. These variables include our expected stock price volatility over the term of the awards, actual and projected employee option exercise behaviors, risk-free interest rates and expected dividends. We also estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from our estimates. Our expected volatility assumption is based on the historical daily closing price of our stock over a period equivalent to the expected life of the options. Income Taxes — We follow the liability method of accounting for income taxes under which deferred tax assets and liabilities are recognized for future tax consequences. A deferred tax asset or liability is computed for both the expected future impact of differences between the financial statement and tax basis of assets and liabilities and for the expected future tax benefit to be derived from tax loss and tax credit carry-forwards. Tax rate changes are reflected in the period such changes are enacted. We assess the recoverability of our net deferred tax assets and the need for a valuation allowance on a quarterly basis. Our assessment includes a number of factors including historical results and taxable income projections for each jurisdiction. The ultimate realization of deferred income tax assets is dependent on the generation of taxable income in appropriate jurisdictions during the periods in which those temporary differences are deductible. We consider the scheduled reversal of deferred income tax liabilities, projected future taxable income, and tax planning strategies in determining the amount of the valuation allowance. Based on the level of historical taxable income and projections for future taxable income over the periods in which the deferred income tax assets are deductible, we determine if we will realize the benefits of these deductible differences. Accounting for income taxes requires a two-step approach to recognize and measure uncertain tax positions. In general, we are subject to regular examination of our income tax returns by the Internal Revenue Service and other tax authorities. The first step is to evaluate the tax position for recognition by determining, if based on the technical merits, it is more likely than not that the position will be sustained upon audit, including resolutions of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement. We regularly assess the likelihood of favorable or unfavorable outcomes resulting from these examinations to determine the adequacy of our provision for income taxes. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. On December 22, 2017, the Tax Act was enacted into law and the new legislation contains several key tax provisions that affected us, including a one-time mandatory transition tax on accumulated foreign earnings and a reduction of the corporate income tax rate to 21%, among others. We are required to recognize the effect of the tax law changes in the period of enactment, such as determining the transition tax, re-measuring our U.S. deferred tax assets and liabilities, as well as reassessing the net realizability of our deferred tax assets and liabilities. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), which allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. Our accounting for the following elements of the Tax Act is incomplete and we were not yet able to make reasonable estimates of the effects, therefore, no provisional adjustments were recorded. Because of the complexity of the new GILTI tax rules, we are continuing to evaluate this provision of the Tax Act and the application of ASC 740 Income Taxes . Under U.S. GAAP, we are required to make an accounting policy choice of either (1) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the “period cost method”) or (2) factoring such amounts into a company’s measurement of its deferred taxes (the “deferred method”). Our selection of an accounting policy with respect to the new GILTI tax rules will depend, in part, on analyzing our global income to determine whether we expect to have future U.S. inclusions in taxable income related to GILTI and, if so, what the impact is expected to be. Because whether we expect to have future U.S. inclusions in taxable income related to GILTI depends on not only our current structure and estimated future results of global operations but also our intent and ability to modify our structure and/or our business, we are not yet able to reasonably estimate the effect of this provision of the Tax Act. Therefore, we have not made any adjustments related to potential GILTI tax in our financial statements and have not made a policy decision regarding whether to record deferred taxes on GILTI. Since the Tax Act was passed late in the fourth quarter of 2017, and ongoing guidance and accounting interpretation is expected over the next 12 months, we consider the accounting for the transition tax, deferred tax re-measurements, and other items to be incomplete due to forthcoming guidance and our ongoing analysis of final year-end data and tax positions. We expect to complete our analysis within the measurement period in accordance with SAB 118. See Note 4. Income Taxes for more information. Commitments and Contingencies — From time to time we are involved in disputes and legal actions arising in the normal course of our business. While we currently believe that the amount of any ultimate loss would not be material to our financial position, the outcome of these actions is inherently difficult to predict. In the event of an adverse outcome, the ultimate loss could have a material adverse effect on our financial position or reported results of operations in a particular period. An unfavorable decision, particularly in patent litigation, could require material changes in production processes and products or result in our inability to ship products or components found to have violated third-party patent rights. We accrue loss contingencies when it is probable that a loss has occurred or will occur and the amount of the loss can be reasonably estimated. Our estimates of probability of losses are subjective, involve significant judgment and uncertainties, and are based on the best information we have at any given point in time. Resolution of these uncertainties in a manner inconsistent with our expectations could have a significant impact on our results of operations and financial condition NEW ACCOUNTING STANDARDS From time to time, the Financial Accounting Standards Board ("FASB") or other standards setting bodies issue new accounting pronouncements. Updates to the FASB Accounting Standards Codification (“ASC”) are communicated through issuance of an Accounting Standards Update (“ASU”). Unless otherwise discussed, we believe that the impact of recently issued guidance, whether adopted or to be adopted in the future, is not expected to have a material impact on the Consolidated Financial Statements upon adoption. In May 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers" and has subsequently issued several supplemental and/or clarifying ASUs (collectively known as "ASC 606"). ASC 606 implements a five-step model for how an entity should recognize revenue in order to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective for fiscal periods beginning after December 15, 2017 and for the interim periods within that year. Advanced Energy has established a cross-functional implementation team to analyze its current portfolio of customer contracts. We have completed the disaggregation of the related sales order data and are finalizing detailed testing of contract elements. The implementation team is close to completion on identifying and implementing changes to existing business processes, controls, and systems in order to support revenue recognition and disclosure under the new standard. Based on our completed reviews of our customer contracts and attribute testing, we expect that revenue with the majority of our customers will continue to be recognized at a point in time, generally upon shipment of products, consistent with our current revenue recognition model. The most significant update identified in connection with the implementation of ASC 606 is related to the recognition of revenue from sales of inventory to customers under vendor managed inventory or just-in-time inventory arrangements. Prior to implementation of ASU 606, revenue was recognized upon transfer of title, which is triggered by the customer's usage of inventory. Under ASC 606, revenue will be recognized upon delivery of inventory to customer site warehouses to align with transfer of control of the inventory. Analysis of variable consideration within customers contracts has been performed and no material updates for ASC 606 adoption were identified. The standard permits the use of either the retrospective or cumulative effect transition method. We will adopt the new revenue guidance effective January 1, 2018 with a cumulative adjustment to the opening balance of Retained earnings as opposed to retrospectively adjusting our prior periods. This adjustment is anticipated to increase our Retained earnings by less than $10 million . Additionally, ongoing impacts of ASC 606 adoption to net income are currently anticipated to be immaterial. Adoption of ASC 606 will also result in future adjustments to the balances of Revenues, Costs of sales, Accounts receivable, and Inventory. We will continue to assess the impact of ASC 606 as adoption is fully completed in 2018, and there remain areas to be fully concluded upon. Additionally, reviews are still underway which may alter current conclusions and the financial impact of ASC 606. In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)," to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within the year of adoption. Early adoption is permitted. Advanced Energy is currently assessing and has not yet determined the impact ASU 2016-02 may have on its Consolidated Financial Statements. October 2016, the FASB issued ASU 2016-16, “Accounting for Income Taxes: Intra-Entity Asset Transfers of Assets Other than Inventory.” ASU 2016-16 changes the timing of income tax recognition for an intercompany sale of assets. ASU 2016-16 requires the seller’s tax effects and the buyer’s deferred taxes to be recognized immediately upon the sale instead of deferring accounting for the income tax implications until the assets are sold to a third party or recovered through use. ASU 2016-16 is effective for fiscal years beginning after December 15, 2017 including interim periods within the year of adoption. Modified retrospective adoption is required with any cumulative-effect adjustment recorded to retained earnings as of the beginning of the period of adoption. Early adoption is allowed but only if adopted in the first quarter of fiscal year 2017. Advanced Energy is currently assessing the impact of ASU 2016-16 adoption and while it has not completed the assessment, it has determined the impact of ASU 2016-16 adoption will require the recognition of deferred tax assets totaling approximately $15 million with a corresponding increase to Retained Earnings in its Consolidated Financial Statements upon adoption. In March 2017, the FASB issued ASU 2017-07, “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” , an update to ASC Topic 715 – Compensation – Retirement Benefits. The amendments in ASU 2017-07 require that the service cost component of the net periodic benefit cost be presented in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of the net periodic benefit cost should be reported separately from the line item that includes the service cost and outside of any subtotal of operating income. ASU 2017-07 is effective for annual reporting periods beginning after December 15, 2017, and for the interim periods within those annual reporting periods. Early adoption is permitted. The Company does not expect this standard will have a material impact on our Consolidated Financial Statements.

Business Acquisition Business A

Business Acquisition Business Acquisition and Disposition (Notes)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	BUSINESS ACQUISITIONS On July 3, 2017, Advanced Energy acquired all of the issued and outstanding shares of capital stock of Excelsys Holdings Limited (“Excelsys”), an electronics manufacturer in Cork, Ireland. This acquisition is part of Advanced Energy’s strategy to continue to grow and diversify its revenue through organic and inorganic opportunities. The high-efficiency, configurable power supplies that Excelsys manufactures for medical and industrial applications will further enhance Advanced Energy’s product portfolio. The components of the fair value of the total consideration transferred for the Excelsys acquisition are as follows: Cash paid to owners $ 18,512 Cash acquired (1,165 ) Total fair value of consideration transferred $ 17,347 The following table summarizes estimated fair values of the assets acquired and liabilities assumed as of July 3, 2017: Accounts receivable $ 1,930 Inventories 1,048 Income taxes receivable 558 Other current assets 47 Property and equipment 256 Deferred income tax asset 35 Accounts payable (1,342 ) Income taxes payable (34 ) Other accrued expenses (719 ) Deferred income tax liabilities (946 ) 833 Amortizable intangible assets: Tradename 182 Customer relationships 1,595 Technology 5,808 Total amortizable intangible assets 7,585 Total identifiable net assets 8,418 Goodwill 8,929 Total fair value of consideration transferred $ 17,347 A summary of the intangible assets acquired, amortization method and estimated useful lives as of July 3, 2017 follows: Amount Amortization Method Useful Life Tradename $ 182 Straight-line 5 Customer relationships 1,595 Straight-line 10 Technology 5,808 Straight-line 10 $ 7,585 Goodwill and intangible assets are recorded in the functional currency of the entity and are subject to changes due to translation at each balance sheet date. The goodwill associated with the acquisition is the result of expected synergies and expansion of the technology into adjacent markets we already serve. Advanced Energy is in the process of finalizing the assessment of fair value for the assets acquired and liabilities assumed.

Discontinued Operations (Notes)

Discontinued Operations (Notes)	12 Months Ended
	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	DISCONTINUED OPERATIONS In December 2015, we completed the wind down of engineering, manufacturing and sales of our solar inverter product line (the "inverter business"). Accordingly, the results of our inverter business have been reflected as “Income (loss) from discontinued operations, net of income taxes” on our Consolidated Statements of Operations for all periods presented herein. The effect of our sales of extended inverter warranties to our customers continues to be reflected in deferred revenue in our Consolidated Balance Sheets. Deferred revenue for extended inverter warranties and the associated costs of warranty service will be reflected in Sales and Cost of goods sold, respectively, from continuing operations in future periods in our Consolidated Statement of Operations, as the deferred revenue, is earned and the associated services are rendered. Extended warranties related to the inverter product line are no longer offered. The significant items included in "Income (loss) from discontinued operations, net of income taxes" are as follows: Year Ended December 31, 2017 2016 2015 Sales $ — $ — $ 95,856 Cost of sales 234 154 139,045 Total operating (income) expenses (including restructuring) (1,576 ) (3,894 ) 232,262 Operating income (loss) from discontinued operations 1,342 3,740 (275,451 ) Other income (expense) 337 2,636 (55 ) Income (loss) from discontinued operations before income taxes 1,679 6,376 (275,506 ) Benefit for income taxes (81 ) (4,130 ) (33,538 ) Income (loss) from discontinued operations, net of income taxes $ 1,760 $ 10,506 $ (241,968 ) Assets and Liabilities of discontinued operations within the Consolidated Balance Sheets are comprised of the following: December 31, 2017 2016 Cash and cash equivalents $ 7,754 $ 7,564 Accounts and other receivables, net 1,363 1,670 Inventories 418 167 Current assets of discontinued operations $ 9,535 $ 9,401 Other assets 72 70 Deferred income tax assets 11,013 15,560 Non-current assets of discontinued operations $ 11,085 $ 15,630 Accounts payable and other accrued expenses 541 3,684 Accrued warranty 7,305 9,254 Accrued restructuring 4 481 Current liabilities of discontinued operations $ 7,850 $ 13,419 Accrued warranty 15,112 20,976 Other liabilities 165 181 Non-current liabilities of discontinued operations $ 15,277 $ 21,157

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	INCOME TAXES The geographic distribution of pretax income from continuing operations is as follows: Years Ended December 31, 2017 2016 2015 Domestic $ 29,088 $ 13,776 $ 13,237 Foreign 169,103 114,300 92,205 $ 198,191 $ 128,076 $ 105,442 The provision for income taxes from continuing operations is summarized as follows: Years Ended December 31, 2017 2016 2015 Current: Federal $ 26,550 $ 3,187 $ 5,823 State 601 351 335 Foreign 9,621 3,081 5,950 Total current provision $ 36,772 $ 6,619 $ 12,108 Deferred: Federal $ 28,297 $ 3,110 $ 569 State (1,000 ) 1,564 870 Foreign (1,979 ) (165 ) 8,413 Total deferred provision 25,318 4,509 9,852 Total provision for income taxes $ 62,090 $ 11,128 $ 21,960 The Company's effective income tax rate is lower than the 35% U.S. statutory tax rate primarily because of benefits from lower-taxed global operations. In 2017, our effective tax rate was also impacted by the effect of the recently enacted U.S. Tax Act, offset partially by a benefit related to the continued wind down of our solar inverter business. The following reconciles our effective tax rate on income from continuing operations to the federal statutory rate of 35%: Years Ended December 31, 2017 2016 2015 Income taxes per federal statutory rate $ 69,348 $ 44,826 $ 37,498 State income taxes, net of federal deduction 1,794 963 1,204 Change in valuation allowance 841 (85 ) 6,503 Transition tax - U.S. Tax Reform 61,690 — — Corporate tax rate change - U.S. Tax Reform 11,177 — — Tax benefit associated with inverter business wind down (33,837 ) — — Stock based compensation (5,263 ) 1,117 (166 ) Tax Amortization (2,558 ) — — Tax effect of foreign operations (47,482 ) (31,651 ) (22,495 ) Uncertain tax positions 4,948 1,636 2,122 Tax credits (658 ) (4,495 ) (969 ) Other permanent items, net 2,090 (1,183 ) (1,737 ) $ 62,090 $ 11,128 $ 21,960 Deferred tax assets and liabilities are recognized for the future tax consequences of differences between the carrying amounts of assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to be reversed. Significant deferred tax assets and liabilities consist of the following: Years Ended December 31, 2017 2016 Deferred tax assets Stock based compensation $ 1,295 $ 2,281 Net operating loss and tax credit carryforwards 40,572 36,145 Pension obligation 3,363 2,338 Excess and obsolete inventory 841 3,031 Deferred revenue 4,519 11,998 Employee bonuses and commissions 1,112 1,908 Other 2,118 3,624 Deferred tax assets 53,820 61,325 Less: Valuation allowance (32,267 ) (26,120 ) Net deferred tax assets 21,553 35,205 Deferred tax liabilities Depreciation and amortization 2,605 2,266 Foreign other 3,448 1,538 Other 62 212 Deferred tax liabilities 6,115 4,016 Net deferred tax assets $ 15,438 $ 31,189 As of December 31, 2017, the Company has recorded a valuation allowance on a portion of its U.S. domestic deferred tax assets of approximately $2.8 million related to state net operating losses. The remaining valuation allowance on deferred tax assets approximates $29.5 million and is associated primarily with operations in Germany, the UK, and India including losses that are both operating and capital in nature. As of December 31, 2017, there is not sufficient positive evidence to conclude that such deferred tax assets will be recognized. The December 31, 2017 valuation allowance balance reflects an increase of $6.1 million during the year. The current rate reconciliation includes $0.8 million of such increase and is primarily attributable to an increase in the state valuation allowance for revisions to estimates of 2017 state income, and forecasted state income, offset by a reduction in the state effective tax rate on deferred tax balances. The balance of the current year valuation allowance increase is associated with foreign activity. Several of our foreign entities have full valuation allowances against their deferred tax balances. Movement during 2017 in these deferred tax balances attributable to rate changes, prior year taxable income adjustments, and movement attributable to annual operating activities requires a corresponding adjustment to the related valuation allowance balances. The changes in valuation allowance associated with these foreign items are included in the rate reconciliation as a component of the tax effects of foreign operations. As of December 31, 2017, the Company had foreign and state tax loss carryforwards of approximately $174.0 million , and $116.6 million , respectively. The Company plans to utilize its U.S. federal net operating loss carryforwards against the recently enacted transition tax. The U.S. state tax loss carryforwards are subject to various limitations under Section 382 of the Internal Revenue Code and applicable state laws. The U.S. state losses will expire from 2019 to 2037 and the majority of the foreign operating losses have no expiration date. Additionally, the majority of the foreign losses are subject to full valuation allowance. The majority of the foreign operating losses have no expiration date. In 2017, we began operating under a tax holiday in one of our foreign jurisdictions. This tax holiday is in effect through June 30, 2027, and may be extended if certain additional requirements are met. The tax holiday is conditional upon our meeting certain employment and investment thresholds. The impact of the tax holiday in 2017 decreased the tax benefit recognized on the current start up tax loss in that jurisdiction by approximately $6.0 million and decreased our income from continuing operations by $0.15 per diluted share. Our accounting for the following elements of the Tax Act is based upon our current understanding of the Tax Act and its estimated impact. However, we were able to make reasonable estimates of certain effects and, therefore, recorded provisional adjustments as follows: The Tax Act reduces the corporate tax rate to 21%, effective January 1, 2018. For certain of our deferred tax assets and deferred tax liabilities, we have recorded a provisional net decrease of $11.1 million with a corresponding adjustment to deferred income tax expense for the year ended December 31, 2017. While we are able to make a reasonable estimate of the impact of the reduction in corporate rate, it may be affected by other analysis related to the Tax Act, including, but not limited to our calculation of deemed repatriation of deferred foreign income and the state tax effect of adjustments made to federal temporary differences. The Transition Tax is a one-time tax on previously untaxed accumulated earnings and profits (E&P) of our foreign subsidiaries. We are able to make a reasonable estimate of the Transition Tax and recorded a provisional Transition Tax obligation of $61.8 million . However, we are continuing to gather additional information to more precisely compute the amount of the Transition Tax. The Transition Tax may be paid over a period of 8 years; 8% per year for years 1 - 5, 15% for year 6, 20% for year 7 and 25% for year 8. We intend to utilize our U.S. net operating loss carryforward to reduce the ultimate cash tax obligation and have currently reflected a total tax payable of $16 million with $1 million classified as a current liability and $15 million classified as Other long term liabilities in the Balance Sheet at December 31, 2017. We previously considered the earnings in our foreign subsidiaries to be indefinitely reinvested and, accordingly, recorded no deferred income taxes. Total estimated foreign earnings totaled $524.9 million at December 31, 2017. The Company continues to assert that such foreign earnings are indefinitely invested in operations outside the U.S. While the Transition Tax results in a reduction to undistributed foreign earnings to tax in the future, an actual repatriation from our foreign subsidiaries could still be subject to additional foreign withholding taxes and U.S. state taxes. We will record the tax effects of any change in our prior assertion with respect to these investments, and disclose any unrecognized deferred tax liability for temporary differences related to our foreign investments, if practicable, in the period that we are first able to make a reasonable estimate. We account for uncertain tax positions by applying a minimum recognition threshold to tax positions before recognizing these positions in the financial statements. The reconciliation of our total gross unrecognized tax benefits is as follows: Years Ended December 31, 2017 2016 2015 Balance at beginning of period $ 11,401 $ 10,049 $ 8,001 Additions based on tax positions taken during a prior period 1,258 104 433 Additions based on tax positions taken during the current period 4,433 2,318 3,413 Reductions related to a lapse of applicable statute of limitations (1,102 ) (1,070 ) (1,798 ) Balance at end of period $ 15,990 $ 11,401 $ 10,049 The full $16.0 million of unrecognized tax benefits, if recognized, will impact the Company’s effective tax rate. In accordance with our accounting policy, we recognize accrued interest and penalties related to unrecognized tax benefits as a component of tax expense. We had $1.0 million and $0.8 million of accrued interest and penalties at December 31, 2017 and 2016, respectively. We do not anticipate a material change to the amount of unrecognized tax positions within the next 12 months. With few exceptions, the Company is no longer subject to federal state or foreign income tax examinations by tax authorities for years before 2014.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share (“EPS”) is computed by dividing income available to common stockholders by the weighted-average number of common shares outstanding during the period. The computation of diluted EPS is similar to the computation of basic EPS except that the denominator is increased to include the number of additional common shares that would have been outstanding (using the if-converted and treasury stock methods), if our outstanding stock options and restricted stock units had been converted to common shares, and if such assumed conversion is dilutive. The following is a reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted earnings per share for the years ended December 31, 2017 , 2016 , and 2015 : Years Ended December 31, 2017 2016 2015 Income from continuing operations, net of income taxes $ 136,101 $ 116,948 $ 83,482 Basic weighted-average common shares outstanding 39,754 39,720 40,746 Assumed exercise of dilutive stock options and restricted stock units 422 311 331 Diluted weighted-average common shares outstanding 40,176 40,031 41,077 Continuing operations: Basic earnings per share $ 3.42 $ 2.94 $ 2.05 Diluted earnings per share $ 3.39 $ 2.92 $ 2.03 The following stock options and restricted units were excluded in the computation of diluted earnings per share because they were anti-dilutive: Years Ended December 31, 2017 2016 2015 Stock options — — 155 Restricted stock units — 1 1 Stock Buyback In September 2015, our Board of Directors authorized a program to repurchase up to $150.0 million of our stock. In November 2017, our Board of Directors approved an extension to the share repurchase program to December 2019 from its original maturity of March 2018. As of December 31, 2017, we had $70.0 million remaining for the authorized repurchase of shares. In November 2015 we entered into a Fixed Dollar Accelerated Share Repurchase Transaction to purchase $50.0 million of shares of our common stock in the open market. A total of 1.7 million shares of our common stock was repurchased under the Fixed Dollar Accelerated Share Repurchase Agreement at an average price of $28.99 per share. In August and December 2017, we entered into Fixed Dollar Share Repurchase Agreements to repurchase $25.0 million and $5.0 million , respectively, of shares of our common stock in the open market. Total shares repurchased under the Fixed Dollar Share Repurchase Agreements in August and December 2017 were 351,292 and 70,700 , respectively, at an average price of $71.16 and $70.65 , respectively, per share. All shares repurchased were executed in the open market, and no shares were repurchased from related parties. Repurchased shares were retired and assumed the status of authorized and unissued shares. Accordingly, the associated cost of the repurchased shares were recognized as a reduction to Additional paid-in capital.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Marketable Securities [Table Text Block]	MARKETABLE SECURITIES AND ASSETS MEASURED AT FAIR VALUE Our investments with original maturities of more than three months at time of purchase and that are intended to be held for no more than 12 months, are considered marketable securities available for sale. Our marketable securities consist of certificates of deposit as follows: December 31, December 31, 2017 2016 Cost Fair Value Cost Fair Value Certificates of deposit 3,103 3,104 4,735 4,737 The maturities of our marketable securities available for sale as of December 31, 2017 are as follows: Earliest Latest Certificates of deposit 4/10/2018 to 10/17/2018 The value and liquidity of the marketable securities we hold are affected by market conditions, as well as the ability of the issuers of such securities to make principal and interest payments when due, and the functioning of the markets in which these securities are traded. As of December 31, 2017 , we do not believe any of the underlying issuers of our marketable securities are at risk of default. The following tables present information about our marketable securities measured at fair value, on a recurring basis, as of December 31, 2017 and December 31, 2016 . The tables indicate the fair value hierarchy of the valuation techniques utilized to determine fair value. We did not have any financial liabilities measured at fair value, on a recurring basis, as of December 31, 2017 or December 31, 2016 . December 31, 2017 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 3,104 $ — $ 3,104 December 31, 2016 Level 1 Level 2 Level 3 Total Certificates of deposit — 4,737 — 4,737 There were no transfers in or out of Level 1, 2, or 3 fair value measurements during the year ended December 31, 2017 .

Derivative Financial Instrument

Derivative Financial Instruments Derivative Instruments (Notes)	12 Months Ended
	Dec. 31, 2017
Derivative [Line Items]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	DERIVATIVE FINANCIAL INSTRUMENTS We are impacted by changes in foreign currency exchange rates. We manage these risks through the use of derivative financial instruments, primarily forward contracts with banks. During the years ended December 31, 2017 , 2016 and 2015 , we entered into foreign currency exchange forward contracts to manage the exchange rate risk associated with intercompany debt denominated in nonfunctional currencies. These derivative instruments are not designated as hedges; however, they do offset the fluctuations of our intercompany debt due to foreign exchange rate changes. These forward contracts are typically for one-month periods. At December 31, 2017 we had outstanding Euro and Pound Sterling forward contracts. We did not have any currency exchange rate contracts as of December 31, 2016 . At December 31, 2015 we had one outstanding Euro forward contract. The notional amount of foreign currency exchange contracts outstanding at December 31, 2017 and 2015 was $16.3 million and $37.2 million , respectively, and the fair value of these contracts was not significant at December 31, 2017 and 2015 . During the years ended December 31, 2017 , 2016 , and 2015 , the gains and losses recorded related to the foreign currency exchange contracts are as follows: Years Ended December 31, 2017 2016 2015 Foreign currency gain (loss) from foreign currency exchange contracts $ (1,438 ) $ (569 ) $ 1,857 These gains and losses were offset by corresponding gains and losses on the related intercompany debt and both are included as a component of other income, net, in our Consolidated Statements of Operations.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Our inventories are valued at the lower of cost or market and computed on a first-in, first-out (FIFO) basis. Components of inventories, net of reserves, are as follows: December 31, 2017 2016 Parts and raw materials $ 58,567 $ 43,278 Work in process 7,986 5,292 Finished goods 11,897 7,200 $ 78,450 $ 55,770

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT, NET Property and equipment, net is comprised of the following: December 31, 2017 2016 Buildings and land $ 1,788 $ 1,581 Machinery and equipment 36,579 32,743 Computer and communication equipment 26,819 24,637 Furniture and fixtures 1,568 1,267 Vehicles 341 357 Leasehold improvements 17,286 15,546 Construction in process 802 644 85,183 76,775 Less: Accumulated depreciation (67,388 ) (63,438 ) Total property and equipment, net $ 17,795 $ 13,337 Depreciation expense recorded in continuing operations and included in selling, general and administrative expense is as follows: Years Ended December 31, 2017 2016 2015 Depreciation expense $ 5,074 $ 3,646 $ 4,464

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
Goodwill [Line Items]
GOODWILL	GOODWILL The following summarizes the changes in goodwill during the years ended December 31, 2017 and 2016 : Goodwill Beginning Balance Additions Effect of Changes in Exchange Rates Ending Balance December 31, 2017 $ 42,125 $ 8,929 $ 2,758 $ 53,812 December 31, 2016 $ 42,729 $ — $ (604 ) $ 42,125 Additions during 2017 are the result of our July 3, 2017 acquisition of Excelsys as described in Note 2. Business Acquisition.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
INTANGIBLE ASSETS	INTANGIBLE ASSETS Intangible assets consisted of the following as of December 31, 2017 and 2016 : December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Technology-based $ 18,702 $ (5,559 ) $ 13,143 Customer relationships 30,034 (10,787 ) 19,247 Trademarks and other 2,623 (1,514 ) 1,109 Total intangible assets $ 51,359 $ (17,860 ) $ 33,499 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Technology-based $ 11,643 $ (3,673 ) $ 7,970 Customer relationships 26,608 (7,451 ) 19,157 Trademarks and other 2,223 (1,279 ) 944 Total intangible assets $ 40,474 $ (12,403 ) $ 28,071 Amortization expense related to intangible assets is as follows: Years Ended December 31, 2017 2016 2015 Amortization expense $ 4,350 $ 4,167 $ 4,368 Estimated amortization expense related to intangibles is as follows: Year Ending December 31, 2018 $ 4,879 2019 4,862 2020 4,175 2021 4,071 2022 3,809 Thereafter 11,703 $ 33,499

Warranties

Warranties	12 Months Ended
	Dec. 31, 2017
Product Warranties Disclosures [Abstract]
WARRANTIES	WARRANTIES Provisions of our sales agreements include customary product warranties, ranging from 12 months to 24 months following installation. The estimated cost of our warranty obligation is recorded when revenue is recognized and is based upon our historical experience by product, configuration and geographic region. Our estimated warranty obligation is included in Other accrued expenses in our Consolidated Balance Sheets. Changes in our product warranty obligation are as follows: Years Ended December 31, 2017 2016 2015 Balances at beginning of period $ 2,329 $ 1,633 $ 1,612 Warranty liabilities acquired 118 — — Increases to accruals 2,029 1,802 1,071 Warranty expenditures (2,184 ) (1,058 ) (1,040 ) Effect of changes in exchange rates 20 (48 ) (10 ) Balances at end of period $ 2,312 $ 2,329 $ 1,633

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Shareholders' Equity and Share-based Payments [Text Block]	STOCK-BASED COMPENSATION As of December 31, 2017 , we had two active stock-based incentive compensation plans; the 2017 Omnibus Incentive Plan and the Employee Stock Purchase Plan (“ESPP”). All new equity compensation grants are issued under these two plans; however, outstanding awards previously issued under inactive plans will continue to vest and remain exercisable in accordance with the terms of the respective plans. Our stock plans are administered by the Board of Directors Compensation Committee. At December 31, 2017 , there were 5.2 million shares reserved and 4.5 million shares available for future grant under our stock-based incentive plans. On May 4, 2017, the shareholders approved the Company's 2017 Omnibus Incentive Plan ("the 2017 Plan") and reserved 5.2 million shares under the plan. The 2017 Plan replaced the 2008 Omnibus Incentive Plan ("the 2008 Plan"), and all awards previously granted under the 2008 Plan continue to vest and/or are exercisable under the 2017 Plan in accordance with their original terms and conditions. The 2017 Plan and 2008 Plan provide for the grant of stock options, stock appreciation rights, restricted stock, stock units (including deferred stock units), unrestricted stock, and dividend equivalent rights. Additionally, awards issued may be issued as performance based awards to align stock compensation awards to the attainment of annual or long-term performance goals. As of December 31, 2017 , there were 4.2 million shares available for grant under the 2017 Plan. Stock-based Compensation Expense We recognize stock-based compensation expense based on the fair value of the awards issued and the functional area of the employee receiving the award. Stock-based compensation for the three years ended December 31, is as follows: Years Ended December 31, 2017 2016 2015 Stock-based compensation expense $ 12,549 $ 6,332 $ 2,810 Our stock-based compensation expense is based on the value of the portion of share-based payment awards that are ultimately expected to vest, assuming estimated forfeitures at the time of grant. Estimated forfeiture rates for our stock-based compensation expense applicable to stock options and restricted stock units ("RSU's") was approximately 17% for the year ended December 31, 2017 and 18% for the years ended December 31, 2016 and 2015 . Restricted Stock Units The fair value of our Restricted Stock Units ("RSUs") is determined based upon the closing fair market value of our common stock on the grant date. Changes in the unvested RSU's during the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Shares Weighted-Average Grant Date Fair Value Shares Weighted-Average Grant Date Fair Value Shares Weighted-Average Grant Date Fair Value RSUs outstanding at beginning of period 354 $ 29.60 234 $ 26.10 357 $ 14.29 RSUs granted 252 63.63 297 30.37 221 26.67 RSUs vested (211 ) 30.62 (157 ) 25.97 (161 ) 14.48 RSUs forfeited (9 ) 33.91 (20 ) 28.32 (183 ) 14.19 RSUs outstanding at end of period 386 51.06 354 29.60 234 26.10 The total intrinsic value of RSUs converted to shares for the years ended December 31, 2017 , 2016 and 2015 were $14.8 million , $5.0 million and $3.8 million , respectively. As of December 31, 2017 , there was $5.5 million of total unrecognized compensation cost, net of expected forfeitures related to non-vested RSUs granted, which is expected to be recognized through fiscal May 2020 , with a weighted-average remaining vesting period of 0.7 years . Stock Options Stock option awards are generally granted with an exercise price equal to the market price of our stock at the date of grant and with either a three or four-year vesting schedule or performance based vesting as determined at the time of grant. Stock option awards generally have a term of 10 years . The fair value of options granted during the year ended December 31, 2015 was estimated on the date of grant using the Black-Scholes-Merton option pricing model using the following assumptions: the risk-free interest rate was 1.1% - 1.4% , the expected term was 4.3 years and expected volatility was 43% . The risk-free interest rate is based on the five-year U.S. Treasury Bill at the time of the grant. We utilize our historical experience in determining the expected term of our stock options and volatility of our common stock. We have not historically issued dividends. Changes in our outstanding stock options during the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Shares Weighted-Average Exercise Price Shares Weighted-Average Exercise Price Shares Weighted-Average Exercise Price Options outstanding at beginning of period 474 $ 17.47 642 $ 17.11 1,022 $ 13.32 Options granted — — — — 171 26.26 Options exercised (152 ) 14.32 (156 ) 15.28 (366 ) 12.97 Options forfeited (2 ) 26.32 (12 ) 26.32 (38 ) 14.55 Options expired (3 ) 11.09 — — (147 ) 12.46 Options outstanding at end of period 317 18.97 474 17.47 642 17.11 Options vested during the year 9 11 368 The total intrinsic value of options exercised for the years ended December 31, 2017 , 2016 and 2015 were $9.7 million , $2.8 million and $5.2 million , respectively. As of December 31, 2017 , there was $ 0.1 million of total unrecognized compensation cost related to stock options granted and outstanding, net of expected forfeitures related to non-vested options, which is expected to be recognized through May 2018 , with a weighted-average remaining vesting period of 0.1 years . Information about our stock options that are outstanding, options that we expect to vest and options that are exercisable at December 31, 2017 are as follows: Options Expected to Vest: Number Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life Aggregate Intrinsic Value Options outstanding 317 $ 18.97 5.2 years $ 15,375 Options expected to vest 317 18.97 5.2 years 15,375 Options exercisable 270 17.71 4.8 years 13,454 The following table summarizes information about the stock options outstanding at December 31, 2017 : Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted-Average Remaining Contractual Life Weighted-Average Exercise Price Number Exercisable Weighted-Average Exercise Price 7.69 - 11.02 45 3.3 years $ 9.74 45 $ 9.74 11.21 - 13.85 41 2.5 years 12.80 41 12.80 14.02 - 14.21 13 2.8 years 14.17 13 14.17 14.50 - 14.50 10 2.8 years 14.50 10 14.50 14.52 - 14.52 8 3.1 years 14.52 8 14.52 15.65 - 15.65 12 2.1 years 15.65 12 15.65 16.25 - 16.25 10 2.3 years 16.25 10 16.25 18.77 - 18.77 57 6.8 years 18.77 57 18.77 24.31 - 24.31 5 7.4 years 24.31 3 24.31 26.32 - 26.32 116 7.1 years 26.32 71 26.32 7.69 - 26.32 317 5.2 years 18.97 270 17.71 Employee Stock Purchase Plan The ESPP, a stockholder-approved plan, provides for the issuance of rights to purchase up to 1,000,000 shares of common stock. In May 2010, shareholders approved an increase from 500,000 to 1,000,000 shares authorized for sale under our ESPP. Employees below the Vice President level are eligible to participate in the ESPP if employed by us for at least 20 hours per week during at least five months per calendar year. Participating employees may contribute up to the lesser of 15% of their eligible earnings or $5,000 during each plan period. Currently, the plan period is six months. The purchase price of common stock purchased under the ESPP is currently equal to the lower of: 1) 85% of the fair market value of our common stock on the commencement date of each plan period or 2) 85% of the fair market value of our common shares on each plan period purchase date. At December 31, 2017 , 0.3 million shares remained available for future issuance under the ESPP. Purchase rights granted under the ESPP are valued using the Black-Scholes-Merton model. As of December 31, 2017 , there was $0.2 million of total unrecognized compensation cost related to the ESPP that is expected to be recognized over a remaining period of five months. Total compensation expense was $ 0.2 million for the years ended December 31, 2017 , 2016 , and 2015 . The fair value of each purchase right granted under the ESPP was estimated on the date of grant using the Black-Scholes-Merton option pricing model with the following assumptions: 2017 2016 2015 Risk-free interest rates 1.07% - 1.45% 0.49% - 0.60% 0.07% - 0.42% Expected dividend yield rates — % — % — % Expected term 0.5 years 0.5 years 0.5 years Expected volatility 33.3 % 28.2 % 27.8 % The risk-free interest rate is based on the six month U.S. Treasury Bill at the time of the grant. Historical company information is the primary basis for selection of the expected dividend yield. The expected term is based on historical experience. Expected volatility is based on historical volatility of our common shares using daily stock price observations.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	RETIREMENT PLANS Defined contribution plans We have a 401(k) profit sharing and retirement savings plan covering substantially all full-time U.S. employees. Participants may defer up to the maximum amount allowed as determined by law. Participants are immediately vested in their contributions. Profit sharing contributions to the plan, which are discretionary, are approved by the Board of Directors. Vesting in the profit sharing contribution account is based on years of service, with most participants fully vested after four years of credited service. For the years ended December 31, 2017 , 2016 , and 2015 our contribution for participants in our 401(k) plan was based on matching 50% of contributions made by employees up to 6% of the employee’s compensation. During the years ended December 31, 2017 , 2016 , and 2015 we recognized total defined contribution plan costs of $ 1.1 million , $ 1.2 million , and $ 0.7 million , respectively. Defined benefit plans In connection with the acquisition of HiTek Power Group, a privately-held provider of high voltage power solutions, in 2014, we acquired the HiTek Power Limited Pension Scheme ("the HiTek Plan"). The HiTek Plan has been closed to new participants since April 1, 2002 and to additional accruals since April 5, 2005. In order to measure the expense and related benefit obligation, various assumptions are made including discount rates used to value the obligation, expected return on plan assets used to fund these expenses and estimated future inflation rates. These assumptions are based on historical experience as well as facts and circumstances. An actuarial analysis is used to measure the expense and liability associated with pension benefits. The net amount of pension liability recorded as of December 31, 2017 and December 31, 2016 was $19.8 million and $18.8 million , respectively, and is included in Other long-term liabilities in our Consolidated Balance Sheets. Anticipated payments to pensioners covered by the HiTek Plan are expected to be between $0.8 million and $1.6 million for each of the next ten years. We are committed to make annual fixed payments of $0.9 million into the Hitek Plan through April 30, 2024, and then $1.8 million from May 1, 2024 through November 30, 2033. The following table sets forth the components of net periodic pension cost for the year ended December 31, 2017 : Year Ended December 31, 2017 2016 2015 Interest cost $ 809 $ 993 $ 1,093 Expected return on plan assets (597 ) (527 ) (562 ) Amortization of actuarial gains and losses 503 264 373 Net periodic pension cost $ 715 $ 730 $ 904 Assumptions used in the determination of the net periodic pension cost are: Year Ended December 31, 2017 2016 2015 Discount rate 2.6 % 2.8 % 3.9 % Expected long-term return on plan assets 4.8 % 4.7 % 4.3 % The status of the HiTek Plan as reflected in "Other long-term liabilities" on our Consolidated Balance Sheets is summarized as follows: Year Ended December 31, 2017 2016 Projected benefit obligation, beginning of year $ 31,110 $ 31,466 Interest cost 809 993 Actuarial loss 35 5,377 Benefits paid (944 ) (1,186 ) Translation adjustment 2,897 (5,540 ) Projected benefit obligation, end of year $ 33,907 $ 31,110 Plan assets, beginning of year $ 12,274 $ 13,677 Actual return on plan assets 597 527 Contributions 877 802 Benefits paid (944 ) (1,186 ) Actuarial gain 179 620 Translation adjustment 1,127 (2,166 ) Plan assets, end of year $ 14,110 $ 12,274 Funded status of plan $ (19,797 ) $ (18,836 ) The fair value of the Company's qualified pension plan assets by category for the years ended December 31, are as follows: December 31, 2017 Level 1 Level 2 Level 3 Total Multi-Asset Fund $ — $ 4,784 $ — $ 4,784 Diversified Growth Fund — 5,009 — 5,009 Index-Linked Gilts — 2,102 — 2,102 Corporate Bonds — 2,173 — 2,173 Cash 42 — — 42 Total $ 42 $ 14,068 $ — $ 14,110 December 31, 2016 Level 1 Level 2 Level 3 Total Multi-Asset Fund $ — $ 3,989 $ — $ 3,989 Diversified Growth Fund — 4,259 — 4,259 Index-Linked Gilts — 1,915 — 1,915 Corporate Bonds — 2,013 — 2,013 Cash 98 — — 98 Total $ 98 $ 12,176 $ — $ 12,274 At December 31, 2017 the HiTek Plan assets of $14.1 million were invested in four separate funds including a multi-asset fund ( 33.9% ), a diversified growth fund ( 35.5% ), an Investment grade long-term bond fund ( 15.4% ) and an index-linked gilt fund ( 14.9% ). The asset and growth funds aim to generate an ‘equity-like’ return over an economic cycle with significantly reduced volatility relative to equity markets and have scope to use a diverse range of asset classes, including equities, bonds, cash and alternatives, e.g. property, infrastructure, high yield bonds, floating rate debt, private, equity, hedge funds and currency. The bond fund and gilt fund are invested in index-linked gilts and corporate bonds. These investments are intended to provide a degree of protection against changes in the value of the HiTek Plan's liabilities related to changes in long-term expectations for interest rates and inflation expectations.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Disputes and Legal Actions We are involved in disputes and legal actions arising in the normal course of our business. While we currently believe that the amount of any ultimate loss would not be material to our financial position, the outcome of these actions is inherently difficult to predict. In the event of an adverse outcome, the ultimate loss could have a material adverse effect on our financial position or reported results of operations. An unfavorable decision in patent litigation also could require material changes in production processes and products or result in our inability to ship products or components found to have violated third-party patent rights. We accrue loss contingencies in connection with our commitments and contingencies, including litigation, when it is probable that a loss has occurred, and the amount of the loss can be reasonably estimated. The Company is currently not a party to any legal action that the Company believes would reasonably have a material adverse impact on its business, financial condition, results of operations or cash flows. Operating Leases We have various operating leases for automobiles, equipment, and office and production facilities. Rent expense under operating leases was approximately $6.5 million in 2017 , $ 6.4 million in 2016 , and $ 5.3 million in 2015 . The future minimum rental payments required under non-cancelable operating leases as of December 31, 2017 are as follows: 2018 $ 7,109 2019 6,381 2020 5,802 2021 4,204 2022 1,273 Thereafter 3,586 $ 28,355

Restructuring Costs

Restructuring Costs	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	RESTRUCTURING COSTS In June 2015, we committed to a restructuring plan in relation to the wind down of our Inverter business. Charges related to this plan that have an effect on continuing operations include strategic headcount reductions, streamlining operational processes and condensing administrative functions to improve efficiencies. This plan was completed in the fourth quarter of 2015. Total cumulative costs through December 31, 2015 were $0.3 million . We did not incur additional costs related to this plan in 2016 or 2017.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Members of our Board of Directors hold various executive positions and serve as directors at other companies, including companies that are our customers. During the years ended December 31, 2017 , 2016 , and 2015 , we engaged in the following transactions with companies related to members of our Board of Directors, as described below: Years Ended December 31, 2017 2016 2015 Sales to related parties $ 1,425 $ 616 $ 706 Number of related party customers 1 2 3 Purchases from related parties $ — $ 43 $ 40 Number of related party vendors — 1 2 Our accounts receivable balance from related party customers with outstanding balances as of December 31, 2017 and December 31, 2016 is as follows: December 31, December 31, 2017 2016 Accounts receivable from related parties $ 27 $ — Number of related party customers 1 — We did not have any outstanding accounts payable with our related parties as of December 31, 2017 or December 31, 2016 .

Geographic and Significant Cust

Geographic and Significant Customer Information (Notes)	12 Months Ended
	Dec. 31, 2017
Segment Reporting Information [Line Items]
Segment Reporting Disclosure [Text Block]	We have operations in the United States, Europe and Asia. Sales and long-lived assets by geographic area and information relating to major customers are presented below. Sales attributed to individual countries are based on customer location. Years Ended December 31, 2017 2016 2015 Sales to external customers: United States $ 453,095 67.5 % $ 327,397 67.7 % $ 268,257 64.7 % Canada 37 — % 161 — % 195 — % North America 453,132 67.5 % 327,558 67.7 % 268,452 64.7 % People's Republic of China 34,045 5.1 % 16,207 3.4 % 12,687 3.1 % Other Asian countries 104,595 15.6 % 77,638 16.1 % 61,839 15.0 % Asia 138,640 20.7 % 93,845 19.5 % 74,526 18.0 % Germany 57,351 8.6 % 48,589 10.0 % 46,719 11.3 % United Kingdom 14,299 2.1 % 13,712 2.8 % 25,100 6.0 % Other European countries 7,590 1.1 % — — % 14 — % Europe 79,240 11.8 % 62,301 12.8 % 71,833 17.3 % Total sales $ 671,012 100.0 % $ 483,704 100.0 % $ 414,811 100.0 % Sales to Applied Materials Inc., our largest customer, was $ 224.8 million or 33.5% of total sales for 2017 , $ 170.2 million , or 35.2% of total sales for 2016 and $123.5 million , or 29.8% of total sales for 2015 . Sales to Lam Research were $ 155.3 million or 23.1% of total sales for 2017 , $ 100.3 million , or 20.7% of total sales for 2016 and $84.2 million , or 20.3% of total sales for 2015 . Our sales to Applied Materials and Lam Research include precision power products used in semiconductor processing and solar, flat panel display, and architectural glass applications. No other customer accounted for 10% or more of our sales during these periods. December 31, 2017 2016 Long-lived assets: United States $ 32,528 $ 33,652 Asia 7,601 3,596 Europe 64,977 46,285 $ 105,106 $ 83,533 Long-lived assets include property and equipment, goodwill and other intangible assets.

Credit Facility

Credit Facility	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	CREDIT FACILITY On July 28, 2017, the Company entered into a Loan Agreement (the “Loan Agreement”) with Bank of America N.A. ("BA") which provides a revolving line of credit of up to $100.0 million subject to certain funding conditions through July 28, 2022. On December 21, 2017, the Company entered into the First Amendment to the Loan Agreement with BA to increase the line of credit to $150.0 million . Interest on amounts drawn shall be paid quarterly based upon the LIBOR Daily Floating Rate then in effect, plus between one and one-quarter ( 1.25% ) and one and three-quarters ( 1.75% ) percentage points depending on the Funded Debt to EBITDA ratio. As of December 31, 2017 , the interest rate was 2.82% . The Loan Agreement also requires the Company to pay the lender on a quarterly basis an unused commitment fee based on credit availability. The obligations under the Loan Agreement are unsecured until the Funded Debt to EBITDA ratio exceeds 2.0 to 1.0, at which time the Company and certain affiliates’ tangible and intangible personal property will be subject to a first priority, perfected lien and security interest in favor of BA pursuant to a Security Agreement. As of December 31, 2017 , the Company is in compliance with all covenants required under the Loan Agreement. Our credit availability under the Loan Agreement was $150.0 million at December 31, 2017 . On September 9, 2016, the Company terminated its Credit Agreement with Wells Fargo Bank, National Association ("Wells Fargo") which provided for a secured revolving credit facility of up to $50.0 million (the "Credit Facility"), subject to a borrowing base calculation. The Company had no outstanding balances at December 31, 2015 and no borrowing during 2016 until the determination of the Credit Agreement. Expense relating to interest, unused commitment fees and amortization of debt issuance costs included in our income from continuing operations is as follows: Years Ended December 31, 2017 2016 2015 Credit facility costs 66 346 456

Quarterly Financial Information

Quarterly Financial Information Disclosure (Notes)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	SUPPLEMENTAL QUARTERLY FINANCIAL DATA (UNAUDITED) The following tables present unaudited quarterly results for each of the eight quarters in the periods ended December 31, 2017 and 2016, in thousands. We believe that all necessary adjustments have been included in the amounts stated below to present fairly such quarterly information. Due to the volatility of the industries in which our customers operate, the operating results for any quarter are not necessarily indicative of results for any subsequent period. Quarter Ended December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 Sales $ 179,214 $ 176,575 $ 165,872 $ 149,351 Gross Profit $ 98,175 $ 92,234 $ 87,141 $ 78,831 Operating income $ 58,062 $ 51,673 $ 47,767 $ 43,268 Income (loss) from continuing operations, net of income taxes $ (29,007 ) $ 83,794 $ 45,873 $ 35,441 Income (loss) from discontinued operations, net of income taxes $ (583 ) $ 70 $ 179 $ 2,094 Net income (loss) $ (29,590 ) $ 83,864 $ 46,052 $ 37,535 Earnings (Loss) Per Share: Continuing Operations: Basic earnings (loss) per share $ (0.73 ) $ 2.11 $ 1.15 $ 0.89 Diluted earnings (loss) per share $ (0.73 ) $ 2.09 $ 1.14 $ 0.88 Discontinued Operations: Basic earnings (loss) per share $ (0.01 ) $ — $ — $ 0.05 Diluted earnings (loss) per share $ (0.01 ) $ — $ — $ 0.05 Net Income (Loss): Basic earnings (loss) per share $ (0.75 ) $ 2.11 $ 1.16 $ 0.94 Diluted earnings (loss) per share $ (0.75 ) $ 2.09 $ 1.14 $ 0.93 Quarter Ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Sales $ 135,343 $ 126,552 $ 118,765 $ 103,044 Gross Profit $ 71,518 $ 66,123 $ 62,046 $ 53,460 Operating income $ 38,546 $ 34,361 $ 30,329 $ 23,621 Income from continuing operations, net of income taxes $ 40,436 $ 29,038 $ 27,254 $ 20,220 Income (loss) from discontinued operations, net of income taxes $ 3,845 $ 1,323 $ 3,277 $ 2,061 Net income (loss) $ 44,281 $ 30,361 $ 30,531 $ 22,281 Earnings per Share: Continuing Operations: Basic earnings per share $ 1.02 $ 0.73 $ 0.69 $ 0.51 Diluted earnings per share $ 1.01 $ 0.73 $ 0.68 $ 0.50 Discontinued Operations: Basic earnings (loss) per share $ 0.10 $ 0.03 $ 0.08 $ 0.05 Diluted earnings (loss) per share $ 0.10 $ 0.03 $ 0.08 $ 0.05 Net Income (loss): Basic earnings (loss) per share $ 1.12 $ 0.77 $ 0.77 $ 0.56 Diluted earnings (loss) per share $ 1.11 $ 0.76 $ 0.76 $ 0.56

Subsequent Events (Notes)

Subsequent Events (Notes)	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENTS Trek Acquisition On February 1, 2018, Advanced Energy acquired Trek Holding Co., LTD ("Trek"), a privately held company with operations in Tokyo, Japan and Lockport, New York for a purchase price of $11.8 million in cash. Trek has a 95% ownership interest in its U.S. subsidiary which is also its primary operation. Trek designs, manufactures and sells high-voltage amplifiers, power supplies and generators, high-performance electrostatic measurement instruments and electrostatic discharge (ESD) sensors and monitors to the global marketplace. Trek's standard and custom-OEM products are used in industry and research in aerospace, automotive, electronics, electrostatics, materials, medical, military, nanotechnology, photovoltaic/solar, physics, plasma, semiconductor and test and measurement applications. For the twelve months ended December 31, 2017, Trek reported unaudited sales of approximately $20 million . Trek’s comprehensive portfolio of power supply products strengthen and accelerate Advanced Energy’s growth in high voltage applications.

Operations and Summary of Sig29

Operations and Summary of Significant Accounting Policies and Estimates Operations and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Note 1. Operations And Summary Of Significant Accounting Policies And Estimates [Abstract]
Schedule of Changes in Doubtful Accounts [Table Text Block]	Changes in allowance for doubtful accounts are summarized as follows: Years Ended December 31, 2017 2016 2015 Balances at beginning of period $ 1,943 $ 8,739 $ 1,052 Additions - charged to expense — 1,332 7,837 Deductions - write-offs, net of recoveries (195 ) (8,128 ) (150 ) Balances at end of period $ 1,748 $ 1,943 $ 8,739

Business Acquisition Business30

Business Acquisition Business Acquisition (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The components of the fair value of the total consideration transferred for the Excelsys acquisition are as follows: Cash paid to owners $ 18,512 Cash acquired (1,165 ) Total fair value of consideration transferred $ 17,347
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table summarizes estimated fair values of the assets acquired and liabilities assumed as of July 3, 2017: Accounts receivable $ 1,930 Inventories 1,048 Income taxes receivable 558 Other current assets 47 Property and equipment 256 Deferred income tax asset 35 Accounts payable (1,342 ) Income taxes payable (34 ) Other accrued expenses (719 ) Deferred income tax liabilities (946 ) 833 Amortizable intangible assets: Tradename 182 Customer relationships 1,595 Technology 5,808 Total amortizable intangible assets 7,585 Total identifiable net assets 8,418 Goodwill 8,929 Total fair value of consideration transferred $ 17,347
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	A summary of the intangible assets acquired, amortization method and estimated useful lives as of July 3, 2017 follows: Amount Amortization Method Useful Life Tradename $ 182 Straight-line 5 Customer relationships 1,595 Straight-line 10 Technology 5,808 Straight-line 10 $ 7,585

Business Acquisition Business D

Business Acquisition Business Disposition (Tables)	12 Months Ended
	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The significant items included in "Income (loss) from discontinued operations, net of income taxes" are as follows: Year Ended December 31, 2017 2016 2015 Sales $ — $ — $ 95,856 Cost of sales 234 154 139,045 Total operating (income) expenses (including restructuring) (1,576 ) (3,894 ) 232,262 Operating income (loss) from discontinued operations 1,342 3,740 (275,451 ) Other income (expense) 337 2,636 (55 ) Income (loss) from discontinued operations before income taxes 1,679 6,376 (275,506 ) Benefit for income taxes (81 ) (4,130 ) (33,538 ) Income (loss) from discontinued operations, net of income taxes $ 1,760 $ 10,506 $ (241,968 ) Assets and Liabilities of discontinued operations within the Consolidated Balance Sheets are comprised of the following: December 31, 2017 2016 Cash and cash equivalents $ 7,754 $ 7,564 Accounts and other receivables, net 1,363 1,670 Inventories 418 167 Current assets of discontinued operations $ 9,535 $ 9,401 Other assets 72 70 Deferred income tax assets 11,013 15,560 Non-current assets of discontinued operations $ 11,085 $ 15,630 Accounts payable and other accrued expenses 541 3,684 Accrued warranty 7,305 9,254 Accrued restructuring 4 481 Current liabilities of discontinued operations $ 7,850 $ 13,419 Accrued warranty 15,112 20,976 Other liabilities 165 181 Non-current liabilities of discontinued operations $ 15,277 $ 21,157

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The significant items included in "Income (loss) from discontinued operations, net of income taxes" are as follows: Year Ended December 31, 2017 2016 2015 Sales $ — $ — $ 95,856 Cost of sales 234 154 139,045 Total operating (income) expenses (including restructuring) (1,576 ) (3,894 ) 232,262 Operating income (loss) from discontinued operations 1,342 3,740 (275,451 ) Other income (expense) 337 2,636 (55 ) Income (loss) from discontinued operations before income taxes 1,679 6,376 (275,506 ) Benefit for income taxes (81 ) (4,130 ) (33,538 ) Income (loss) from discontinued operations, net of income taxes $ 1,760 $ 10,506 $ (241,968 ) Assets and Liabilities of discontinued operations within the Consolidated Balance Sheets are comprised of the following: December 31, 2017 2016 Cash and cash equivalents $ 7,754 $ 7,564 Accounts and other receivables, net 1,363 1,670 Inventories 418 167 Current assets of discontinued operations $ 9,535 $ 9,401 Other assets 72 70 Deferred income tax assets 11,013 15,560 Non-current assets of discontinued operations $ 11,085 $ 15,630 Accounts payable and other accrued expenses 541 3,684 Accrued warranty 7,305 9,254 Accrued restructuring 4 481 Current liabilities of discontinued operations $ 7,850 $ 13,419 Accrued warranty 15,112 20,976 Other liabilities 165 181 Non-current liabilities of discontinued operations $ 15,277 $ 21,157

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	The geographic distribution of pretax income from continuing operations is as follows: Years Ended December 31, 2017 2016 2015 Domestic $ 29,088 $ 13,776 $ 13,237 Foreign 169,103 114,300 92,205 $ 198,191 $ 128,076 $ 105,442
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The provision for income taxes from continuing operations is summarized as follows: Years Ended December 31, 2017 2016 2015 Current: Federal $ 26,550 $ 3,187 $ 5,823 State 601 351 335 Foreign 9,621 3,081 5,950 Total current provision $ 36,772 $ 6,619 $ 12,108 Deferred: Federal $ 28,297 $ 3,110 $ 569 State (1,000 ) 1,564 870 Foreign (1,979 ) (165 ) 8,413 Total deferred provision 25,318 4,509 9,852 Total provision for income taxes $ 62,090 $ 11,128 $ 21,960
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The following reconciles our effective tax rate on income from continuing operations to the federal statutory rate of 35%: Years Ended December 31, 2017 2016 2015 Income taxes per federal statutory rate $ 69,348 $ 44,826 $ 37,498 State income taxes, net of federal deduction 1,794 963 1,204 Change in valuation allowance 841 (85 ) 6,503 Transition tax - U.S. Tax Reform 61,690 — — Corporate tax rate change - U.S. Tax Reform 11,177 — — Tax benefit associated with inverter business wind down (33,837 ) — — Stock based compensation (5,263 ) 1,117 (166 ) Tax Amortization (2,558 ) — — Tax effect of foreign operations (47,482 ) (31,651 ) (22,495 ) Uncertain tax positions 4,948 1,636 2,122 Tax credits (658 ) (4,495 ) (969 ) Other permanent items, net 2,090 (1,183 ) (1,737 ) $ 62,090 $ 11,128 $ 21,960
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Significant deferred tax assets and liabilities consist of the following: Years Ended December 31, 2017 2016 Deferred tax assets Stock based compensation $ 1,295 $ 2,281 Net operating loss and tax credit carryforwards 40,572 36,145 Pension obligation 3,363 2,338 Excess and obsolete inventory 841 3,031 Deferred revenue 4,519 11,998 Employee bonuses and commissions 1,112 1,908 Other 2,118 3,624 Deferred tax assets 53,820 61,325 Less: Valuation allowance (32,267 ) (26,120 ) Net deferred tax assets 21,553 35,205 Deferred tax liabilities Depreciation and amortization 2,605 2,266 Foreign other 3,448 1,538 Other 62 212 Deferred tax liabilities 6,115 4,016 Net deferred tax assets $ 15,438 $ 31,189
Summary of Income Tax Contingencies [Table Text Block]	Years Ended December 31, 2017 2016 2015 Balance at beginning of period $ 11,401 $ 10,049 $ 8,001 Additions based on tax positions taken during a prior period 1,258 104 433 Additions based on tax positions taken during the current period 4,433 2,318 3,413 Reductions related to a lapse of applicable statute of limitations (1,102 ) (1,070 ) (1,798 ) Balance at end of period $ 15,990 $ 11,401 $ 10,049

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted EPS	The following is a reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted earnings per share for the years ended December 31, 2017 , 2016 , and 2015 : Years Ended December 31, 2017 2016 2015 Income from continuing operations, net of income taxes $ 136,101 $ 116,948 $ 83,482 Basic weighted-average common shares outstanding 39,754 39,720 40,746 Assumed exercise of dilutive stock options and restricted stock units 422 311 331 Diluted weighted-average common shares outstanding 40,176 40,031 41,077 Continuing operations: Basic earnings per share $ 3.42 $ 2.94 $ 2.05 Diluted earnings per share $ 3.39 $ 2.92 $ 2.03
Schedule of stock options and restricted units were excluded in the computation of diluted earnings per share because they were anti-dilutive	The following stock options and restricted units were excluded in the computation of diluted earnings per share because they were anti-dilutive: Years Ended December 31, 2017 2016 2015 Stock options — — 155 Restricted stock units — 1 1

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities [Table Text Block]	Our marketable securities consist of certificates of deposit as follows: December 31, December 31, 2017 2016 Cost Fair Value Cost Fair Value Certificates of deposit 3,103 3,104 4,735 4,737
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	The following tables present information about our marketable securities measured at fair value, on a recurring basis, as of December 31, 2017 and December 31, 2016 . The tables indicate the fair value hierarchy of the valuation techniques utilized to determine fair value. We did not have any financial liabilities measured at fair value, on a recurring basis, as of December 31, 2017 or December 31, 2016 . December 31, 2017 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 3,104 $ — $ 3,104 December 31, 2016 Level 1 Level 2 Level 3 Total Certificates of deposit — 4,737 — 4,737
The maturities of our marketable securities available for sale	The maturities of our marketable securities available for sale as of December 31, 2017 are as follows: Earliest Latest Certificates of deposit 4/10/2018 to 10/17/2018

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Components of inventories	Our inventories are valued at the lower of cost or market and computed on a first-in, first-out (FIFO) basis. Components of inventories, net of reserves, are as follows: December 31, 2017 2016 Parts and raw materials $ 58,567 $ 43,278 Work in process 7,986 5,292 Finished goods 11,897 7,200 $ 78,450 $ 55,770

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Details of property and equipment	Property and equipment, net is comprised of the following: December 31, 2017 2016 Buildings and land $ 1,788 $ 1,581 Machinery and equipment 36,579 32,743 Computer and communication equipment 26,819 24,637 Furniture and fixtures 1,568 1,267 Vehicles 341 357 Leasehold improvements 17,286 15,546 Construction in process 802 644 85,183 76,775 Less: Accumulated depreciation (67,388 ) (63,438 ) Total property and equipment, net $ 17,795 $ 13,337
Depreciation expense recorded in continuing operations	Depreciation expense recorded in continuing operations and included in selling, general and administrative expense is as follows: Years Ended December 31, 2017 2016 2015 Depreciation expense $ 5,074 $ 3,646 $ 4,464

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill [Line Items]
Schedule of the changes in goodwill	The following summarizes the changes in goodwill during the years ended December 31, 2017 and 2016 : Goodwill Beginning Balance Additions Effect of Changes in Exchange Rates Ending Balance December 31, 2017 $ 42,125 $ 8,929 $ 2,758 $ 53,812 December 31, 2016 $ 42,729 $ — $ (604 ) $ 42,125 Additions during 2017 are the result of our July 3, 2017 acquisition of Excelsys as described in Note 2. Business Acquisition.

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Schedule of other intangible assets	Intangible assets consisted of the following as of December 31, 2017 and 2016 : December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Technology-based $ 18,702 $ (5,559 ) $ 13,143 Customer relationships 30,034 (10,787 ) 19,247 Trademarks and other 2,623 (1,514 ) 1,109 Total intangible assets $ 51,359 $ (17,860 ) $ 33,499 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Technology-based $ 11,643 $ (3,673 ) $ 7,970 Customer relationships 26,608 (7,451 ) 19,157 Trademarks and other 2,223 (1,279 ) 944 Total intangible assets $ 40,474 $ (12,403 ) $ 28,071
Schedule of amortization expense relating to other intangible assets	Amortization expense related to intangible assets is as follows: Years Ended December 31, 2017 2016 2015 Amortization expense $ 4,350 $ 4,167 $ 4,368
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Estimated amortization expense related to intangibles is as follows: Year Ending December 31, 2018 $ 4,879 2019 4,862 2020 4,175 2021 4,071 2022 3,809 Thereafter 11,703 $ 33,499

Warranties (Tables)

Warranties (Tables)	12 Months Ended
	Dec. 31, 2017
Product Warranties Disclosures [Abstract]
Changes in accrued product warranties	Years Ended December 31, 2017 2016 2015 Balances at beginning of period $ 2,329 $ 1,633 $ 1,612 Warranty liabilities acquired 118 — — Increases to accruals 2,029 1,802 1,071 Warranty expenditures (2,184 ) (1,058 ) (1,040 ) Effect of changes in exchange rates 20 (48 ) (10 ) Balances at end of period $ 2,312 $ 2,329 $ 1,633

Stock-Based Compensation Stock-

Stock-Based Compensation Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Changes in the unvested RSU's during the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Shares Weighted-Average Grant Date Fair Value Shares Weighted-Average Grant Date Fair Value Shares Weighted-Average Grant Date Fair Value RSUs outstanding at beginning of period 354 $ 29.60 234 $ 26.10 357 $ 14.29 RSUs granted 252 63.63 297 30.37 221 26.67 RSUs vested (211 ) 30.62 (157 ) 25.97 (161 ) 14.48 RSUs forfeited (9 ) 33.91 (20 ) 28.32 (183 ) 14.19 RSUs outstanding at end of period 386 51.06 354 29.60 234 26.10
Share-based Compensation, Stock Options, Activity [Table Text Block]	Information about our stock options that are outstanding, options that we expect to vest and options that are exercisable at December 31, 2017 are as follows: Options Expected to Vest: Number Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life Aggregate Intrinsic Value Options outstanding 317 $ 18.97 5.2 years $ 15,375 Options expected to vest 317 18.97 5.2 years 15,375 Options exercisable 270 17.71 4.8 years 13,454
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]	The following table summarizes information about the stock options outstanding at December 31, 2017 : Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted-Average Remaining Contractual Life Weighted-Average Exercise Price Number Exercisable Weighted-Average Exercise Price 7.69 - 11.02 45 3.3 years $ 9.74 45 $ 9.74 11.21 - 13.85 41 2.5 years 12.80 41 12.80 14.02 - 14.21 13 2.8 years 14.17 13 14.17 14.50 - 14.50 10 2.8 years 14.50 10 14.50 14.52 - 14.52 8 3.1 years 14.52 8 14.52 15.65 - 15.65 12 2.1 years 15.65 12 15.65 16.25 - 16.25 10 2.3 years 16.25 10 16.25 18.77 - 18.77 57 6.8 years 18.77 57 18.77 24.31 - 24.31 5 7.4 years 24.31 3 24.31 26.32 - 26.32 116 7.1 years 26.32 71 26.32 7.69 - 26.32 317 5.2 years 18.97 270 17.71
Employee Stock [Member]
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]	The fair value of each purchase right granted under the ESPP was estimated on the date of grant using the Black-Scholes-Merton option pricing model with the following assumptions: 2017 2016 2015 Risk-free interest rates 1.07% - 1.45% 0.49% - 0.60% 0.07% - 0.42% Expected dividend yield rates — % — % — % Expected term 0.5 years 0.5 years 0.5 years Expected volatility 33.3 % 28.2 % 27.8 %
Time Based [Member]
Schedule of Stock Options Roll Forward [Table Text Block]	Changes in our outstanding stock options during the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Shares Weighted-Average Exercise Price Shares Weighted-Average Exercise Price Shares Weighted-Average Exercise Price Options outstanding at beginning of period 474 $ 17.47 642 $ 17.11 1,022 $ 13.32 Options granted — — — — 171 26.26 Options exercised (152 ) 14.32 (156 ) 15.28 (366 ) 12.97 Options forfeited (2 ) 26.32 (12 ) 26.32 (38 ) 14.55 Options expired (3 ) 11.09 — — (147 ) 12.46 Options outstanding at end of period 317 18.97 474 17.47 642 17.11 Options vested during the year 9 11 368
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted-Average Remaining Contractual Life Weighted-Average Exercise Price Number Exercisable Weighted-Average Exercise Price 7.69 - 11.02 45 3.3 years $ 9.74 45 $ 9.74 11.21 - 13.85 41 2.5 years 12.80 41 12.80 14.02 - 14.21 13 2.8 years 14.17 13 14.17 14.50 - 14.50 10 2.8 years 14.50 10 14.50 14.52 - 14.52 8 3.1 years 14.52 8 14.52 15.65 - 15.65 12 2.1 years 15.65 12 15.65 16.25 - 16.25 10 2.3 years 16.25 10 16.25 18.77 - 18.77 57 6.8 years 18.77 57 18.77 24.31 - 24.31 5 7.4 years 24.31 3 24.31 26.32 - 26.32 116 7.1 years 26.32 71 26.32 7.69 - 26.32 317 5.2 years 18.97 270 17.71

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs [Table Text Block]	The following table sets forth the components of net periodic pension cost for the year ended December 31, 2017 : Year Ended December 31, 2017 2016 2015 Interest cost $ 809 $ 993 $ 1,093 Expected return on plan assets (597 ) (527 ) (562 ) Amortization of actuarial gains and losses 503 264 373 Net periodic pension cost $ 715 $ 730 $ 904
Schedule of Assumptions Used [Table Text Block]	Assumptions used in the determination of the net periodic pension cost are: Year Ended December 31, 2017 2016 2015 Discount rate 2.6 % 2.8 % 3.9 % Expected long-term return on plan assets 4.8 % 4.7 % 4.3 %
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]	The status of the HiTek Plan as reflected in "Other long-term liabilities" on our Consolidated Balance Sheets is summarized as follows: Year Ended December 31, 2017 2016 Projected benefit obligation, beginning of year $ 31,110 $ 31,466 Interest cost 809 993 Actuarial loss 35 5,377 Benefits paid (944 ) (1,186 ) Translation adjustment 2,897 (5,540 ) Projected benefit obligation, end of year $ 33,907 $ 31,110 Plan assets, beginning of year $ 12,274 $ 13,677 Actual return on plan assets 597 527 Contributions 877 802 Benefits paid (944 ) (1,186 ) Actuarial gain 179 620 Translation adjustment 1,127 (2,166 ) Plan assets, end of year $ 14,110 $ 12,274 Funded status of plan $ (19,797 ) $ (18,836 )
Schedule of Allocation of Plan Assets, Fair Value Hieracrchy [Table Text Block}	The fair value of the Company's qualified pension plan assets by category for the years ended December 31, are as follows: December 31, 2017 Level 1 Level 2 Level 3 Total Multi-Asset Fund $ — $ 4,784 $ — $ 4,784 Diversified Growth Fund — 5,009 — 5,009 Index-Linked Gilts — 2,102 — 2,102 Corporate Bonds — 2,173 — 2,173 Cash 42 — — 42 Total $ 42 $ 14,068 $ — $ 14,110 December 31, 2016 Level 1 Level 2 Level 3 Total Multi-Asset Fund $ — $ 3,989 $ — $ 3,989 Diversified Growth Fund — 4,259 — 4,259 Index-Linked Gilts — 1,915 — 1,915 Corporate Bonds — 2,013 — 2,013 Cash 98 — — 98 Total $ 98 $ 12,176 $ — $ 12,274

Commitments and Contingencies S

Commitments and Contingencies Schedule of Future Minimum Lease Payments (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	The future minimum rental payments required under non-cancelable operating leases as of December 31, 2017 are as follows: 2018 $ 7,109 2019 6,381 2020 5,802 2021 4,204 2022 1,273 Thereafter 3,586 $ 28,355

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule of related party transactions	During the years ended December 31, 2017 , 2016 , and 2015 , we engaged in the following transactions with companies related to members of our Board of Directors, as described below: Years Ended December 31, 2017 2016 2015 Sales to related parties $ 1,425 $ 616 $ 706 Number of related party customers 1 2 3 Purchases from related parties $ — $ 43 $ 40 Number of related party vendors — 1 2 Our accounts receivable balance from related party customers with outstanding balances as of December 31, 2017 and December 31, 2016 is as follows: December 31, December 31, 2017 2016 Accounts receivable from related parties $ 27 $ — Number of related party customers 1 —

Geographic and Significant Cu45

Geographic and Significant Customer Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	Years Ended December 31, 2017 2016 2015 Sales to external customers: United States $ 453,095 67.5 % $ 327,397 67.7 % $ 268,257 64.7 % Canada 37 — % 161 — % 195 — % North America 453,132 67.5 % 327,558 67.7 % 268,452 64.7 % People's Republic of China 34,045 5.1 % 16,207 3.4 % 12,687 3.1 % Other Asian countries 104,595 15.6 % 77,638 16.1 % 61,839 15.0 % Asia 138,640 20.7 % 93,845 19.5 % 74,526 18.0 % Germany 57,351 8.6 % 48,589 10.0 % 46,719 11.3 % United Kingdom 14,299 2.1 % 13,712 2.8 % 25,100 6.0 % Other European countries 7,590 1.1 % — — % 14 — % Europe 79,240 11.8 % 62,301 12.8 % 71,833 17.3 % Total sales $ 671,012 100.0 % $ 483,704 100.0 % $ 414,811 100.0 %

Quarterly Financial Informati46

Quarterly Financial Information Disclosure (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]	December 31, 2017 2016 Long-lived assets: United States $ 32,528 $ 33,652 Asia 7,601 3,596 Europe 64,977 46,285 $ 105,106 $ 83,533 Long-lived assets include property and equipment, goodwill and other intangible assets.
Quarterly Financial Information [Table Text Block]	The following tables present unaudited quarterly results for each of the eight quarters in the periods ended December 31, 2017 and 2016, in thousands. We believe that all necessary adjustments have been included in the amounts stated below to present fairly such quarterly information. Due to the volatility of the industries in which our customers operate, the operating results for any quarter are not necessarily indicative of results for any subsequent period. Quarter Ended December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 Sales $ 179,214 $ 176,575 $ 165,872 $ 149,351 Gross Profit $ 98,175 $ 92,234 $ 87,141 $ 78,831 Operating income $ 58,062 $ 51,673 $ 47,767 $ 43,268 Income (loss) from continuing operations, net of income taxes $ (29,007 ) $ 83,794 $ 45,873 $ 35,441 Income (loss) from discontinued operations, net of income taxes $ (583 ) $ 70 $ 179 $ 2,094 Net income (loss) $ (29,590 ) $ 83,864 $ 46,052 $ 37,535 Earnings (Loss) Per Share: Continuing Operations: Basic earnings (loss) per share $ (0.73 ) $ 2.11 $ 1.15 $ 0.89 Diluted earnings (loss) per share $ (0.73 ) $ 2.09 $ 1.14 $ 0.88 Discontinued Operations: Basic earnings (loss) per share $ (0.01 ) $ — $ — $ 0.05 Diluted earnings (loss) per share $ (0.01 ) $ — $ — $ 0.05 Net Income (Loss): Basic earnings (loss) per share $ (0.75 ) $ 2.11 $ 1.16 $ 0.94 Diluted earnings (loss) per share $ (0.75 ) $ 2.09 $ 1.14 $ 0.93 Quarter Ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Sales $ 135,343 $ 126,552 $ 118,765 $ 103,044 Gross Profit $ 71,518 $ 66,123 $ 62,046 $ 53,460 Operating income $ 38,546 $ 34,361 $ 30,329 $ 23,621 Income from continuing operations, net of income taxes $ 40,436 $ 29,038 $ 27,254 $ 20,220 Income (loss) from discontinued operations, net of income taxes $ 3,845 $ 1,323 $ 3,277 $ 2,061 Net income (loss) $ 44,281 $ 30,361 $ 30,531 $ 22,281 Earnings per Share: Continuing Operations: Basic earnings per share $ 1.02 $ 0.73 $ 0.69 $ 0.51 Diluted earnings per share $ 1.01 $ 0.73 $ 0.68 $ 0.50 Discontinued Operations: Basic earnings (loss) per share $ 0.10 $ 0.03 $ 0.08 $ 0.05 Diluted earnings (loss) per share $ 0.10 $ 0.03 $ 0.08 $ 0.05 Net Income (loss): Basic earnings (loss) per share $ 1.12 $ 0.77 $ 0.77 $ 0.56 Diluted earnings (loss) per share $ 1.11 $ 0.76 $ 0.76 $ 0.56

Operations and Summary of Sig47

Operations and Summary of Significant Accounting Policies and Estimates Summary of Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in Allowance For Doubtful Accounts [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 1,748	$ 1,943	$ 8,739	$ 1,052
Provision for Doubtful Accounts	0	1,332	7,837
Allowance for Doubtful Accounts Receivable, Charge-offs	$ (195)	$ (8,128)	$ (150)

Operations and Summary of Sig48

Operations and Summary of Significant Accounting Policies and Estimates Operations and Summary of Significant Accounting Policies and Estimates (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders' Equity Attributable to Parent	$ 520,641	$ 520,641	$ 392,074	$ 263,580	$ 474,965
Customer deposits	6,402	$ 6,402	5,774
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life		20 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life		40 years
Machinery, equipment, furniture and fixtures and vehicles [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life		3 years
Machinery, equipment, furniture and fixtures and vehicles [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life		10 years
Retained Earnings [Member]
Stockholders' Equity Attributable to Parent	$ 333,225	$ 333,225	$ 195,364	$ 67,910	$ 226,396
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Concentration Risk, Percentage		10.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Concentration Risk, Percentage	42.00%		41.10%

Operations and Summary of Sig49

Operations and Summary of Significant Accounting Policies and Estimates Summary of Useful Life Property Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Minimum [Member] | Building [Member]
Property, Plant and Equipment, Useful Life	20 years

Operations and Summary of Sig50

Operations and Summary of Significant Accounting Policies and Estimates Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
Deferred Service Revenue	$ 37,500	$ 37,500	$ 40,800
Restricted Cash and Cash Equivalents	1,200	1,200
Retained Earnings (Accumulated Deficit)	333,225	333,225	195,364
Non-cash reserve for potential bad debts		0	$ 0	$ 5,967
European Tax Authority [Member]
Restricted Cash and Cash Equivalents	500	500
European Tax Authority [Member] [Member]
Restricted Cash and Cash Equivalents	200	200
Collateral for Pcard Program [Member]
Restricted Cash and Cash Equivalents	$ 500	$ 500
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage		10.00%
Customer Concentration Risk [Member] | Lam Research [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage	6.20%		18.90%
Concentration Risk, Amount	$ 5,421	$ 5,421	$ 14,317
Customer Concentration Risk [Member] | Applied Materials, Inc. [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage	42.00%		41.10%
Concentration Risk, Amount	$ 36,755	36,755	$ 31,100
Accounting Standards Update 2016-16 [Member] | Scenario, Forecast [Member]
Deferred Income Tax Assets, Net					$ 15,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | Pro Forma [Member]
Retained Earnings (Accumulated Deficit)	$ 10,000	$ 10,000
Retained Earnings [Member] | Accounting Standards Update 2016-16 [Member] | Scenario, Forecast [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 15,000
Computer and Communication Equipment [Member]
Property, Plant and Equipment, Useful Life		3 years

Operations and Summary of Sig51

Operations and Summary of Significant Accounting Policies and Estimates Schedule of Adjustments due to New Accounting Standards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets from discontinued operations	$ 9,535				$ 9,401				$ 9,535	$ 9,401
Total current assets	595,225				438,334				595,225	438,334
Non-current assets from discontinued operations	11,085				15,630				11,085	15,630
Total assets	733,308				571,529				733,308	571,529
Total current liabilities	106,119				95,046				106,119	95,046
Non-current deferred income tax liabilities	4,556				1,008				4,556	1,008
Total liabilities	212,667				179,455				212,667	179,455
Total liabilities and stockholders' equity	733,308				571,529				733,308	571,529
Net deferred tax assets	15,438				31,189				15,438	31,189
Income from continuing operations before income taxes									198,191	128,076	$ 105,442
Provision for income taxes									62,090	11,128	21,960
Income from continuing operations	(29,007)	$ 83,794	$ 45,873	$ 35,441	40,436	$ 29,038	$ 27,254	$ 20,220	136,101	116,948	83,482
Income (loss) from discontinued operations, net of income taxes									1,760	10,506	(241,968)
Net income (loss)	$ (29,590)	$ 83,864	$ 46,052	$ 37,535	$ 44,281	$ 30,361	$ 30,531	$ 22,281	$ 137,861	$ 127,454	$ (158,486)
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.73)	$ 2.11	$ 1.15	$ 0.89	$ 1.02	$ 0.73	$ 0.69	$ 0.51	$ 3.42	$ 2.94	$ 2.05
Income (Loss) from Continuing Operations, Per Diluted Share	(0.73)	2.09	1.14	0.88	1.01	0.73	0.68	0.50	3.39	2.92	2.03
Basic earnings (loss) per share	(0.75)	2.11	1.16	0.94	1.12	0.77	0.77	0.56	3.47	3.21	(3.89)
Diluted earnings (loss) per share	$ (0.75)	$ 2.09	$ 1.14	$ 0.93	$ 1.11	$ 0.76	$ 0.76	$ 0.56	$ 3.43	$ 3.18	$ (3.89)
Basic weighted-average common shares outstanding									39,754	39,720	40,746
Diluted weighted-average common shares outstanding									40,176	40,031	41,077
Net cash provided by operating activities									$ 182,701	$ 119,287	$ 104,709
Net cash provided by investing activities									(28,082)	300	(13,265)
Net cash provided by financing activities									(31,307)	2,171	(45,528)
EFFECT OF CURRENCY TRANSLATION ON CASH									2,208	(1,932)	(1,467)
Increase in cash and cash equivalents									$ 125,520	$ 119,797	$ 44,435

Business Acquisition Narrative

Business Acquisition Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 53,812	$ 42,125	$ 42,729

Business Acquisition Schedule o

Business Acquisition Schedule of Components of Fair Value of Consideration Transferred (Details) - Excelsys Acquisition [Member] $ in Thousands	Jul. 03, 2017USD ($)
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 18,512
Cash Acquired from Acquisition	1,165
Business Combination, Consideration Transferred	$ 17,347

Business Acquisition Summary of

Business Acquisition Summary of Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jul. 03, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 53,812	$ 42,125	$ 42,729
Excelsys Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	$ 1,930
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	1,048
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	256
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	7,585
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	8,418
Goodwill	8,929
Business Combination, Consideration Transferred	17,347
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Income Taxes Receivable	558
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	47
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	35
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	1,342
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Income Taxes Payable	34
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	719
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	946
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets Acquired (Liabilities) Assumed	833
Tradename [Member] | Excelsys Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	182
Customer Relationships [Member] | Excelsys Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	1,595
Technology-based [Member] | Excelsys Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 5,808

Business Acquisition Schedule55

Business Acquisition Schedule of Intangible Assets Acquired, Amortization Method, and Estimated Useful Lives (Details) - Excelsys Acquisition [Member] $ in Thousands	Jul. 03, 2017USD ($)
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 7,585
Tradename [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 182
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 1,595
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Technology-based [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 5,808
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years

Business Acquisition Business56

Business Acquisition Business Disposition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	$ 0	$ 0	$ 95,856
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	234	154	139,045
Disposal Group, Including Discontinued Operation, Operating Expense	(1,576)	(3,894)	232,262
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	1,342	3,740	(275,451)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	1,679	6,376	(275,506)
Discontinued Operation, Tax Effect of Discontinued Operation	(81)	(4,130)	(33,538)
Income (loss) from discontinued operations, net of income taxes	$ 1,760	$ 10,506	$ (241,968)

Discontinued Operations Discont

Discontinued Operations Discontinued Operations_Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Less cash and cash equivalents from discontinued operations	$ 7,754	$ 7,564	$ 11,277
Disposal Group, Including Discontinued Operation, Revenue	0	0	95,856
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	234	154	139,045
Disposal Group, Including Discontinued Operation, Operating Expense	(1,576)	(3,894)	232,262
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	1,342	3,740	(275,451)
Disposal Group, Including Discontinued Operation, Other Income	337	2,636
Disposal Group, Including Discontinued Operation, Other Expense			(55)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	1,679	6,376	(275,506)
Discontinued Operation, Tax Effect of Discontinued Operation	(81)	(4,130)	(33,538)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,760	10,506	$ (241,968)
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	1,363	1,670
Disposal Group, Including Discontinued Operation, Inventory	418	167
Current assets from discontinued operations	9,535	9,401
Disposal Group, Including Discontinued Operation, Intangible Assets, Noncurrent	72	70
Disposal Group, Including Discontinued Operation, Deferred Tax Assets, Noncurrent	11,013	15,560
Non-current assets from discontinued operations	11,085	15,630
Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities	541	3,684
Disposal Groups_Including Discontinued Operations_Accrued Warranty Current	7,305	9,254
Disposal Groups_Including Discontinued Operations_Accrued Restructuring	4	481
Current liabilities from discontinued operations	7,850	13,419
Disposal Groups_Including Discontinued Operations_Accrued Warranty NonCurrent	15,112	20,976
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent	165	181
Non-current liabilities from discontinued operations	$ 15,277	$ 21,157

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Income Tax Holiday, Aggregate Dollar Amount	$ 6,000
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit)	11,100
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit)	61,800
Tax Cuts And Jobs Act of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Liability	16,000
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Liability, Current	1,000
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Liability, Noncurrent	15,000
Unrecognized Tax Benefits	15,990	$ 11,401	$ 10,049	$ 8,001
Income (Loss) from Continuing Operations before Income Taxes, Domestic	29,088	13,776	$ 13,237
Deferred Tax Assets, Inventory	841	3,031
Deferred Tax Assets, Deferred Income	4,519	11,998
Deferred Tax Assets, Operating Loss Carryforwards	40,572	36,145
Deferred Tax Liabilities, Property, Plant and Equipment	2,605	2,266
Deferred Tax Assets, Other	2,118	3,624
Deferred Tax Assets, Valuation Allowance	32,267	26,120
Net deferred tax assets	15,438	31,189
Undistributed Earnings of Foreign Subsidiaries	524,900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	1,000	$ 800
State Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Valuation Allowances and Reserves, Balance	3,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Valuation Allowances and Reserves, Balance	$ 29,500
Income Tax Holiday, Income Tax Benefits Per Share	$ 0.15
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 174,000
State Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 116,600

Income Taxes Components of Inco

Income Taxes Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ 26,550	$ 3,187	$ 5,823
Current State and Local Tax Expense (Benefit)	601	351	335
Current Foreign Tax Expense (Benefit)	9,621	3,081	5,950
Current Income Tax Expense (Benefit)	36,772	6,619	12,108
Deferred Federal Income Tax Expense (Benefit)	28,297	3,110	569
Deferred State and Local Income Tax Expense (Benefit)	(1,000)	1,564	870
Deferred Foreign Income Tax Expense (Benefit)	(1,979)	(165)	8,413
Deferred Income Tax Expense (Benefit)	25,318	4,509	9,852
Income Tax Expense (Benefit)	$ 62,090	$ 11,128	$ 21,960

Income Taxes Composition of Def

Income Taxes Composition of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Tax Deferred Expense [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Bonuses	$ 1,112	$ 1,908
Deferred Tax Assets, Inventory	841	3,031
Deferred Tax Assets, Deferred Income	4,519	11,998
Deferred Tax Assets, Operating Loss Carryforwards	40,572	36,145
Deferred Tax Assets, Other	2,118	3,624
Deferred Tax Assets, Valuation Allowance	32,267	26,120
Net deferred tax assets	15,438	31,189
Deferred Tax Liabilities [Abstract]
Deferred Tax Liabilities, Property, Plant and Equipment	$ 2,605	$ 2,266

Income Taxes Schedule of Curren

Income Taxes Schedule of Current and Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	$ 1,295	$ 2,281
Deferred Tax Assets, Operating Loss Carryforwards	40,572	36,145
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions	3,363	2,338
Deferred Tax Assets, Inventory	841	3,031
Deferred Tax Assets, Deferred Income	4,519	11,998
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Bonuses	1,112	1,908
Deferred Tax Assets, Other	2,118	3,624
Deferred Tax Assets, Gross	53,820	61,325
Deferred Tax Assets, Valuation Allowance	(32,267)	(26,120)
Deferred Tax Assets, Net of Valuation Allowance	21,553	35,205
Deferred Tax Liabilities, Property, Plant and Equipment	2,605	2,266
Deferred Tax Liabilities, Foreign Other	3,448	1,538
Deferred Tax Liabilities, Other	62	212
Deferred Tax Liabilities, Net	6,115	4,016
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	18,841	32,197
Deferred Tax Assets, Net	$ 15,438	$ 31,189

Income Taxes Earnings Before In

Income Taxes Earnings Before Income Taxes by Geographical Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 29,088	$ 13,776	$ 13,237
Income (Loss) from Continuing Operations before Income Taxes, Foreign	169,103	114,300	92,205
Income from continuing operations before income taxes	$ 198,191	$ 128,076	$ 105,442

Income Taxes Reconciliation of

Income Taxes Reconciliation of Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 15,990	$ 11,401	$ 10,049	$ 8,001
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	1,258	104	433
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	4,433	2,318	3,413
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	$ (1,102)	$ (1,070)	$ (1,798)

Income Taxes Reconciliation o64

Income Taxes Reconciliation of Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 69,348	$ 44,826	$ 37,498
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	1,794	963	1,204
Valuation Allowance, Deferred Tax Asset, Change in Amount	841	(85)	6,503
EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017TransitionTax	61,690	0	0
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Change in tax rate, Percent	11,177	0	0
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount	(33,837)	0	0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount	(5,263)	1,117	(166)
Effective Income Tax Rate Reconciliation, Tax Amortization, Amount	(2,558)	0	0
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	(47,482)	(31,651)	(22,495)
Effective Income Tax Reconciliation, Uncertain Tax Position Reserves, net	4,948	1,636	2,122
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	2,090	(1,183)	(1,737)
Income Tax Expense (Benefit)	62,090	11,128	21,960
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ (658)	$ (4,495)	$ (969)

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Dec. 31, 2017	Aug. 31, 2017	Nov. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 16, 2015
Earnings Per Share [Abstract]
Stock Repurchase Program, Authorized Amount							$ 150,000
Stock Repurchased and Retired During Period, Shares				422,000	343,000	1,382,000
Stock Repurchased and Retired During Period, Value				$ (29,993)	$ 0	$ (50,000)
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 70,000			70,000
Treasury Stock, Common, Value	$ 5,000	$ 25,000	$ 50,000	$ 5,000
Treasury Stock, Shares, Acquired	70,700	351,292	1,700,000
Treasury Stock Acquired, Average Cost Per Share	$ 70.65	$ 71.16	$ 28.99

Earnings Per Share Reconciliati

Earnings Per Share Reconciliation of the weighted-average shares outstanding used in the calculation of basic and diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income from continuing operations, net of income taxes									$ 136,101	$ 116,948	$ 83,482
Income from continuing operations	$ (29,007)	$ 83,794	$ 45,873	$ 35,441	$ 40,436	$ 29,038	$ 27,254	$ 20,220	$ 136,101	$ 116,948	$ 83,482
Basic weighted-average common shares outstanding (in shares)									39,754	39,720	40,746
Assumed exercise of dilutive stock options and restricted stock units									422	311	331
Diluted weighted-average common shares outstanding (in shares)									40,176	40,031	41,077
Income from Continuing Operations:
BASIC EARNINGS PER SHARE (in dollars per share)	$ (0.73)	$ 2.11	$ 1.15	$ 0.89	$ 1.02	$ 0.73	$ 0.69	$ 0.51	$ 3.42	$ 2.94	$ 2.05
Diluted earnings per share (in dollars per share)	$ (0.73)	$ 2.09	$ 1.14	$ 0.88	$ 1.01	$ 0.73	$ 0.68	$ 0.50	$ 3.39	$ 2.92	$ 2.03

Earnings Per Share Schedule of

Earnings Per Share Schedule of stock options and restricted units were excluded in the computation of diluted earnings per share because they were anti-dilutive (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted units excluded from the computation of diluted earnings per share because they were anti-dilutive	0	0	155
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted units excluded from the computation of diluted earnings per share because they were anti-dilutive	0	1	1

Marketable Securities (Details)

Marketable Securities (Details) - Certificates of Deposit [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 3,104	$ 4,737
Available-for-sale Debt Securities, Amortized Cost Basis	$ 3,103	$ 4,735

Marketable Securities The matur

Marketable Securities The maturities of our marketable securities available for sale (Details) - Certificates of Deposit [Member]	12 Months Ended
	Dec. 31, 2017
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturities of marketable securites, by date	Oct. 17, 2018
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturities of marketable securites, by date	Apr. 10, 2018

Marketable Securities Fair Valu

Marketable Securities Fair Value Schedule of Financial Assets Measured at Fair Value (Details) - Certificates of Deposit [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	$ 3,104	$ 4,737
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	3,104	4,737
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	$ 0	$ 0

Derivative Financial Instrume71

Derivative Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative, Notional Amount	$ 16,300		$ 37,200
Foreign Exchange [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (1,438)	$ (569)	$ 1,857

Inventories Components of inven

Inventories Components of inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Parts and raw materials	$ 58,567	$ 43,278
Work in process	7,986	5,292
Finished goods	11,897	7,200
Inventories	$ 78,450	$ 55,770

Property and Equipment Details

Property and Equipment Details of property and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 85,183	$ 76,775
Less: Accumulated depreciation	(67,388)	(63,438)
Property and equipment, net	17,795	13,337
Buildings and Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,788	1,581
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	36,579	32,743
Computer and Communication Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,819	24,637
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,568	1,267
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	341	357
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	17,286	15,546
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 802	$ 644

Property and Equipment Deprecia

Property and Equipment Depreciation expense recorded in continuing operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 5,074	$ 3,646	$ 4,464

Goodwill Schedule of the change

Goodwill Schedule of the changes in goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Gross carrying amount, beginning of period	$ 42,125	$ 42,729
Goodwill, Acquired During Period	8,929	0
Goodwill, Foreign Currency Translation Gain (Loss)	2,758	(604)
Gross carrying amount, end of period	$ 53,812	$ 42,125

Intangible Assets Schedule of o

Intangible Assets Schedule of other intangible assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 51,359	$ 40,474
Accumulated Amortization	(17,860)	(12,403)
Finite-Lived Intangible Assets, Net	33,499	28,071
Intangible Assets, Net	33,499
Technology-based [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	18,702	11,643
Accumulated Amortization	(5,559)	(3,673)
Finite-Lived Intangible Assets, Net	13,143	7,970
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	30,034	26,608
Accumulated Amortization	(10,787)	(7,451)
Finite-Lived Intangible Assets, Net	19,247	19,157
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,623	2,223
Accumulated Amortization	(1,514)	(1,279)
Finite-Lived Intangible Assets, Net	$ 1,109	$ 944

Intangible Assets Schedule of a

Intangible Assets Schedule of amortization expense relating to other intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 4,350	$ 4,167	$ 4,368

Intangible Assets Schedule of F

Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
2,017	$ 4,879
2,018	4,862
2,019	4,175
2,020	4,071
2,021	3,809
Thereafter	11,703
Finite-lived intangible assets, net	$ 33,499	$ 28,071

Warranties Changes in accrued p

Warranties Changes in accrued product warranties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balances at beginning of period	$ 2,329	$ 1,633	$ 1,612
Standard and Extended Product Warranty Accrual, Additions from Business Acquisition	118	0	0
Increases to accruals related to sales during the period	2,029	1,802	1,071
Product Warranty Expense	(2,184)	(1,058)	(1,040)
Standard Product Warranty Accrual, Foreign Currency Translation Gain (Loss)	20	(48)	(10)
Balances at end of period	$ 2,312	$ 2,329	$ 1,633

Warranties Warranty Narrative (

Warranties Warranty Narrative (Details)	12 Months Ended
	Dec. 31, 2017
Minimum [Member]
Standard Product Warranty Term	12 months
Maximum [Member]
Standard Product Warranty Term	24 months

Stock-Based Compensation Narrat

Stock-Based Compensation Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 04, 2017	May 01, 2010	Apr. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 9,687,000	$ 2,815,000	$ 5,203,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 month
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved	5,200,000			5,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,500,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 100,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	7 months 27 days
Share based Compensation Arrangement By Share based Payment Award Options Contractual Term	10 years
Allocated Share-based Compensation Expense	$ 12,549,000	$ 6,332,000	$ 2,810,000
Estimated Forfeiture rates for Share Based Compensation	17.00%	18.00%	18.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate			43.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			4 years 3 months
2017 OMNIBUS Incentive Plan [Member] [Domain]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,200,000
Restricted Stock Units (RSUs) [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 5,500,000
Employee Stock [Member]
Allocated Share-based Compensation Expense		$ 200,000	$ 200,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	33.30%	28.20%	27.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months	6 months	6 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			1.40%
Maximum [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.45%	0.60%	0.42%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 14,757,000	$ 4,988,000	$ 3,782,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 63.63	$ 30.37	$ 26.67
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1,000,000				1,000,000	500,000
Share-based Compensation Arrangement By Share-based Payment Award, Employee Contribution, Amount	$ 5,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	85.00%
Employee Stock [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	300,153
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 200,000
Allocated Share-based Compensation Expense	$ 200,000
Employee Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement By Share-based Payment Award, Employee Contribution, Percent	15.00%

Stock-Based Compensation Stoc82

Stock-Based Compensation Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Allocated Share-based Compensation Expense	$ 12,549	$ 6,332	$ 2,810

Stock-Based Compensation Fair V

Stock-Based Compensation Fair Value Assumptions by Grant Year (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			4 years 3 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate			43.00%
Estimated Forfeiture rates for Share Based Compensation	17.00%	18.00%	18.00%
Allocated Share-based Compensation Expense	$ 12,549	$ 6,332	$ 2,810
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months	6 months	6 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	33.30%	28.20%	27.80%
Allocated Share-based Compensation Expense		$ 200	$ 200
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			1.10%
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 7.69
Minimum [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.07%	0.49%	0.07%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			1.40%
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 26.32
Maximum [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.45%	0.60%	0.42%

Stock-Based Compensation Schedu

Stock-Based Compensation Schedule of Weighted Average Fair Value and Intrinsic Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 9,687	$ 2,815	$ 5,203

Stock-Based Compensation Change

Stock-Based Compensation Changes in Outstanding Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	317,000
Time Based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 14.32	$ 15.28	$ 12.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	(2,000)	(12,000)	(38,000)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	$ 26.32	$ 26.32	$ 14.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period	(3,000)	0	(147,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.97	$ 17.47	$ 17.11	$ 13.32
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0	$ 0	$ 26.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(152,000)	(156,000)	(366,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	171,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 11.09	$ 0	$ 12.46
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	317,000	474,000	642,000	1,022,000
Options Vested During the Year	$ 9	$ 11	$ 368

Stock-Based Compensation Sche86

Stock-Based Compensation Schedules of Options Expected to Vest (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Equity [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	317,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 18.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 2 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $	$ 15,375,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number | shares	317,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price | $ / shares	$ 18.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	5 years 2 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value | $	$ 15,375,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	270,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 17.71
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 10 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $	$ 13,454,000

Stock-Based Compensation Sche87

Stock-Based Compensation Schedule of Stock Options by Exercise Price (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 17.71
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	270,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	317,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	5 years 2 months
Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 9.74
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 9.74
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	45,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	45,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 3 months
Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 12.80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 12.80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	41,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	41,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 6 months
Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 14.17
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 14.17
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	13,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	13,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 10 months
Range Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 14.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 14.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	10,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	10,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 10 months
Range Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 14.52
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 14.52
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	8,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	8,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 1 month
Range Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 15.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 15.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	12,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	12,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 1 month
Range Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 16.25
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 16.25
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	10,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	10,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 4 months
Range Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 18.77
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 18.77
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	57,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	57,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	6 years 9 months
Range Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 24.31
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 24.31
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	3,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	5,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	7 years 5 months
Range Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 26.32
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 26.32
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	71,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	116,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	7 years 1 month
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		1.40%
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 26.32
Maximum [Member] | Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	9.51
Maximum [Member] | Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	11.02
Maximum [Member] | Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	13.85
Maximum [Member] | Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	14.52
Maximum [Member] | Range 5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	15.65
Maximum [Member] | Range 6
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	16.25
Maximum [Member] | Range 7
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	18.77
Maximum [Member] | Range 8
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	24.31
Maximum [Member] | Range 9
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	25.28
Maximum [Member] | Range 10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	26.32
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		1.10%
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	7.69
Minimum [Member] | Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	7.69
Minimum [Member] | Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	11.02
Minimum [Member] | Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	11.21
Minimum [Member] | Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	14.02
Minimum [Member] | Range 5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	15.65
Minimum [Member] | Range 6
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	16.25
Minimum [Member] | Range 7
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	18.77
Minimum [Member] | Range 8
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	24.31
Minimum [Member] | Range 9
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	25.28
Minimum [Member] | Range 10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 26.32

Stock-Based Compensation Chan88

Stock-Based Compensation Changes in RSU (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	386	354	234	357
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 51.06	$ 29.60	$ 26.10	$ 14.29
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	252	297	221
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(211)	(157)	(161)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 30.62	$ 25.97	$ 14.48
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(9)	(20)	(183)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 33.91	$ 28.32	$ 14.19
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 63.63	$ 30.37	$ 26.67

Stock-Based Compensation Sche89

Stock-Based Compensation Schedule of Weighted Average Fair Value and Intrinsic Value for RSUs (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 9,687	$ 2,815	$ 5,203
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 51.06	$ 29.60	$ 26.10	$ 14.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 14,757	$ 4,988	$ 3,782

Retirement Plans (Details)

Retirement Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 1,100	$ 1,200	$ 700
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.60%	2.80%	3.90%
Defined Benefit Plan, Interest Cost	$ 809	$ 993	$ 1,093
Defined Benefit Plan, Expected Return on Plan Assets	4.80%	4.70%	4.30%
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	$ 2,897	$ (5,540)
Defined Benefit Plan, Fair Value of Plan Assets	14,110	12,274	$ 13,677
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	597	527
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	1,127	(2,166)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	19,797	18,836
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	597	527	562
Defined Benefit Plan, Amortization of Gain (Loss)	(503)	(264)	(373)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	715	730	$ 904
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 4,784	3,989
Defined Benefit Plan, Actual Plan Asset Allocations	33.90%
Defined Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 5,009	4,259
Defined Benefit Plan, Actual Plan Asset Allocations	35.50%
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 2,173	2,013
Defined Benefit Plan, Actual Plan Asset Allocations	15.40%
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 2,102	$ 1,915
Defined Benefit Plan, Actual Plan Asset Allocations	14.90%

Retirement Plans Fair Value of

Retirement Plans Fair Value of Pension Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 14,110	$ 12,274	$ 13,677
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,068	12,176
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42	98
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,784	3,989
Multi-asset Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,784	3,989
Multi-asset Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Multi-asset Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,009	4,259
Defined Growth Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,009	4,259
Defined Growth Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Growth Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,102	1,915
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,102	1,915
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,173	2,013
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,173	2,013
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42	98
Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 42	$ 98

Retirement Plans Status of Pens

Retirement Plans Status of Pension Benefit Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	$ 33,907	$ 31,110	$ 31,466
Defined Benefit Plan, Interest Cost	809	993	1,093
Defined Benefit Plan, Benefit Obligation, Benefits Paid	944	1,186
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	1,127	(2,166)
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	2,897	(5,540)
Defined Benefit Plan, Fair Value of Plan Assets	14,110	12,274	$ 13,677
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	597	527
Defined Benefit Plan, Plan Assets, Contributions by Employer	877	802
Defined Benefit Plan, Plan Assets, Benefits Paid	944	1,186
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(19,797)	(18,836)
Projected Benefit Obligation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	35	5,377
Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 179	$ 620

Retirement Plans Pension Assump

Retirement Plans Pension Assumptions (Details)	12 Months Ended
	Dec. 31, 2017Rate	Dec. 31, 2016Rate	Dec. 31, 2015Rate
Retirement Benefits [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.60%	2.80%	3.90%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	4.80%	4.70%	4.30%

Retirement Plans Schedule of Fa

Retirement Plans Schedule of Fair Value of Benefit Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 14,110	$ 12,274	$ 13,677
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,068	12,176
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42	98
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,784	3,989
Multi-asset Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,784	3,989
Multi-asset Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Multi-asset Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,009	4,259
Defined Growth Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,009	4,259
Defined Growth Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Growth Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,102	1,915
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,102	1,915
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Index-Linked Gilts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,173	2,013
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,173	2,013
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42	98
Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 42	$ 98

Retirement Plans Defined Benefi

Retirement Plans Defined Benefit Plan Asset Allocation (Details)	Dec. 31, 2017Rate
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	33.90%
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	14.90%
Defined Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	35.50%
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	15.40%

Retirement Plans Defined Bene96

Retirement Plans Defined Benefit Plan, Expected Payments to Participants (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Minimum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments	$ 0.8
Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments	$ 1.6

Retirement Plans Defined Bene97

Retirement Plans Defined Benefit Plan, Funding Commitments (Details) $ in Millions	Dec. 31, 2017USD ($)
HPLPS Payments from May 1, 2024 through November 30, 2033 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 1.8
HPLPS Payments through April 30, 2024 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0.9

Retirement Plans Defined Contri

Retirement Plans Defined Contribution Plan Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined Contribution Plan, Cost	$ 1.1	$ 1.2	$ 0.7

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 6.5	$ 6.4	$ 5.3

Commitments and Contingencie100

Commitments and Contingencies Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Future Minimum Payments, Due in One Years	$ 7,109
Operating Leases, Future Minimum Payments, Due in Two Years	6,381
Operating Leases, Future Minimum Payments, Due in Three Years	5,802
Operating Leases, Future Minimum Payments, Due in Four Years	4,204
Operating Leases, Future Minimum Payments, Due in Five Years	1,273
Operating Leases, Future Minimum Payments, Due Thereafter	3,586
Operating Leases, Future Minimum Payments Due	$ 28,355

Restructuring Costs Schedule of

Restructuring Costs Schedule of the components of our restructuring costs incurred (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 0	$ 0	$ 198
April Two Thousand Fifteen Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 300

Related Party Transactions (Det

Related Party Transactions (Details) - Companies	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transactions, Number of Companies	1	0
Related Party Purchases [Member]
Related Party Transactions, Number of Companies	0	1	2

Related Party Transactions Sche

Related Party Transactions Schedule of related party transactions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Companies	Dec. 31, 2016USD ($)Companies	Dec. 31, 2015USD ($)Companies
Revenue from Related Parties | $	$ 1,425	$ 616	$ 706
Accounts Receivable, Related Parties | $	$ 27	$ 0
Related Party Transactions, Number of Companies	1	0
Related Party Transaction, Purchases from Related Party | $	$ 0	$ 43	$ 40
Sales [Member]
Related Party Transactions, Number of Companies			3
Management [Member]
Related Party Transactions, Number of Companies	1	2
Related Party Purchases [Member]
Related Party Transactions, Number of Companies	0	1	2

Geographic and Significant C104

Geographic and Significant Customer Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	$ 578,650	$ 410,580	$ 350,834
Sales Revenue, Goods, Net [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	$ 224,832	$ 170,162	$ 123,500
Concentration Risk, Percentage	33.50%	35.20%	29.80%
Sales Revenue, Goods, Net [Member] | Lam Research [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	$ 155,312	$ 100,270
Concentration Risk, Percentage	23.10%	20.70%
Sales Revenue, Goods, Net [Member] | Lam Research and Novellus Systems, Inc. [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net			$ 84,200
Concentration Risk, Percentage			20.30%

Geographic and Significant C105

Geographic and Significant Customer Information Sales by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues									$ 453,095	$ 327,397	$ 268,257
Disclosure on Geographic Areas, Revenue from External Customers attributed to Entitie's Country of Domicile, Percentage									67.50%	67.70%	64.70%
Revenue, Net	$ 179,214	$ 176,575	$ 165,872	$ 149,351	$ 135,343	$ 126,552	$ 118,765	$ 103,044	$ 671,012	$ 483,704	$ 414,811
CANADA
Segment Reporting Information [Line Items]
Revenues									$ 37	$ 161	$ 195
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									0.00%	0.00%	0.00%
NORTH AMERICA
Segment Reporting Information [Line Items]
Revenues									$ 453,132	$ 327,558	$ 268,452
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									67.50%	67.70%	64.70%
CHINA
Segment Reporting Information [Line Items]
Revenues									$ 34,045	$ 16,207	$ 12,687
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									5.10%	3.40%	3.10%
Other Asian Countries [Member]
Segment Reporting Information [Line Items]
Revenues									$ 104,595	$ 77,638	$ 61,839
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									15.60%	16.10%	15.00%
Asia [Member]
Segment Reporting Information [Line Items]
Revenues									$ 138,640	$ 93,845	$ 74,526
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									20.70%	19.50%	18.00%
GERMANY
Segment Reporting Information [Line Items]
Revenues									$ 57,351	$ 48,589	$ 46,719
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									8.60%	10.00%	11.30%
UNITED KINGDOM
Segment Reporting Information [Line Items]
Revenues									$ 14,299	$ 13,712	$ 25,100
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									2.10%	2.80%	6.00%
Other European Countries [Member]
Segment Reporting Information [Line Items]
Revenues									$ 7,590	$ 0	$ 14
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									1.10%	0.00%	0.00%
Europe [Member]
Segment Reporting Information [Line Items]
Revenues									$ 79,240	$ 62,301	$ 71,833
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									11.80%	12.80%	17.30%

Geographic and Significant C106

Geographic and Significant Customer Information Schedule of Long-lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 17,795	$ 13,337
Long-Lived Assets	105,106	83,533
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	32,528	33,652
Asia [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	7,601	3,596
Europe [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 64,977	$ 46,285

Credit Facility Narrative (Det

Credit Facility Narrative (Details)	Dec. 21, 2017	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jul. 28, 2017USD ($)	Sep. 09, 2016USD ($)
Wells Fargo Bank [Member]
Line of Credit Facility [Line Items]
Interest Expense		$ 66,000	$ 346,000	$ 456,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Long-term Debt				$ 0		$ 0
Revolving Credit Facility [Member] | Bank of America N.A. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity		$ 150,000,000			$ 100,000,000
Debt, Weighted Average Interest Rate		2.82%
Funded Debt To EBITDA Ratio	2
Revolving Credit Facility [Member] | Wells Fargo Bank [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity						$ 50,000,000
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Bank of America N.A. [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Revolving Credit Facility [Member] | Funded Debt To EBITDA Ratio [Member] | Bank of America N.A. [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%

Quarterly Financial Informat108

Quarterly Financial Information Disclosure Supplemental Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue, Net	$ 179,214	$ 176,575	$ 165,872	$ 149,351	$ 135,343	$ 126,552	$ 118,765	$ 103,044	$ 671,012	$ 483,704	$ 414,811
Gross Profit	98,175	92,234	87,141	78,831	71,518	66,123	62,046	53,460	356,381	253,147	216,870
Restructuring expense									0	0	198
Operating Income (Loss)	58,062	51,673	47,767	43,268	38,546	34,361	30,329	23,621	200,770	126,857	106,656
Income from continuing operations	(29,007)	83,794	45,873	35,441	40,436	29,038	27,254	20,220	136,101	116,948	83,482
Income (loss) from discontinued operations, net of income taxes	(583)	70	179	2,094	3,845	1,323	3,277	2,061	1,760	10,506	(241,968)
Net income (loss)	$ (29,590)	$ 83,864	$ 46,052	$ 37,535	$ 44,281	$ 30,361	$ 30,531	$ 22,281	$ 137,861	$ 127,454	$ (158,486)
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.73)	$ 2.11	$ 1.15	$ 0.89	$ 1.02	$ 0.73	$ 0.69	$ 0.51	$ 3.42	$ 2.94	$ 2.05
Income (Loss) from Continuing Operations, Per Diluted Share	(0.73)	2.09	1.14	0.88	1.01	0.73	0.68	0.50	3.39	2.92	2.03
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0	0	0.05	0.10	0.03	0.08	0.05	0.04	0.26	(5.94)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	(0.01)	0	0	0.05	0.10	0.03	0.08	0.05	0.04	0.26	(5.94)
Basic earnings (loss) per share	(0.75)	2.11	1.16	0.94	1.12	0.77	0.77	0.56	3.47	3.21	(3.89)
Diluted earnings (loss) per share	$ (0.75)	$ 2.09	$ 1.14	$ 0.93	$ 1.11	$ 0.76	$ 0.76	$ 0.56	$ 3.43	$ 3.18	$ (3.89)

Subsequent Events (Details)

Subsequent Events (Details) - Trek Holding Co., LTD [Member] - USD ($) $ in Millions	Feb. 01, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Business Acquisition, Pro Forma Revenue		$ 20
Subsequent Event [Member]
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross	$ 11.8
Noncontrolling Interest, Ownership Percentage by Parent	95.00%