ADTRAN (ADTN) 10-Q 5 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 04, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	ADTRAN INC
Trading Symbol	ADTN
Entity Central Index Key	0000926282
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		47,826,323
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	000-24612
Entity Tax Identification Number	63-0918200
Entity Address, Address Line One	901 Explorer Boulevard
Entity Address, City or Town	Huntsville
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35806-2807
City Area Code	256
Local Phone Number	963-8000
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, Par Value $0.01 per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 96,407	$ 105,504
Short-term investments	28,754	3,246
Accounts receivable, less allowance for doubtful accounts of $81 and $128 at September 30, 2019 and December 31, 2018, respectively	90,647	99,385
Other receivables	18,927	36,699
Inventory, net	104,941	99,848
Prepaid expenses and other current assets	10,327	10,744
Total Current Assets	350,003	355,426
Property, plant and equipment, net	73,384	80,635
Deferred tax assets, net	6,492	37,187
Goodwill	6,968	7,106
Intangibles, net	29,113	33,183
Other assets	23,283	5,668
Long-term investments	90,632	108,822
Total Assets	579,875	628,027
Current Liabilities
Accounts payable	52,842	60,054
Bonds payable	25,600	1,000
Unearned revenue	14,022	17,940
Accrued expenses	15,697	11,746
Accrued wages and benefits	16,569	14,752
Income tax payable, net	3,420	12,518
Total Current Liabilities	128,150	118,010
Non-current unearned revenue	4,581	5,296
Other non-current liabilities	52,189	33,842
Bonds payable		24,600
Total Liabilities	184,920	181,748
Commitments and contingencies (see Note 16)
Stockholders’ Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 47,826 shares outstanding at September 30, 2019 and 79,652 shares issued and 47,751 shares outstanding at December 31, 2018	797	797
Additional paid-in capital	272,854	267,670
Accumulated other comprehensive loss	(16,506)	(14,416)
Retained earnings	827,783	883,975
Treasury stock at cost: 31,826 and 31,901 shares at September 30, 2019 and December 31, 2018, respectively	(689,973)	(691,747)
Total Stockholders’ Equity	394,955	446,279
Total Liabilities and Stockholders’ Equity	$ 579,875	$ 628,027

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts	$ 81	$ 128
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	79,652,000	79,652,000
Common stock, shares outstanding	47,826,000	47,751,000
Treasury stock, shares	31,826,000	31,901,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Sales
Total Sales	$ 114,092	$ 140,335	$ 414,274	$ 389,189
Cost of Sales
Total Cost of Sales	67,761	81,887	242,316	241,012
Gross Profit	46,331	58,448	171,958	148,177
Selling, general and administrative expenses	30,912	30,750	99,663	96,361
Research and development expenses	31,835	29,877	95,546	93,455
Asset impairments	3,872		3,872
Gain on contingency			(1,230)
Operating Loss	(20,288)	(2,179)	(25,893)	(41,639)
Interest and dividend income	610	825	1,893	2,604
Interest expense	(128)	(134)	(382)	(398)
Net investment gain (loss)	(216)	4,507	8,195	5,400
Other income (expense), net	1,616	201	2,266	(73)
Gain on bargain purchase of a business, net				11,322
Income (Loss) Before Income Taxes	(18,406)	3,220	(13,921)	(22,784)
Income tax (expense) benefit	(27,717)	4,369	(27,437)	11,889
Net Income (Loss)	$ (46,123)	$ 7,589	$ (41,358)	$ (10,895)
Weighted average shares outstanding – basic	47,824	47,710	47,803	47,927
Weighted average shares outstanding – diluted	47,824	47,834	47,803	47,927
Earnings (loss) per common share – basic	$ (0.96)	$ 0.16	$ (0.87)	$ (0.23)
Earnings (loss) per common share – diluted	$ (0.96)	$ 0.16	$ (0.87)	$ (0.23)
Network Solutions [Member]
Sales
Total Sales	$ 94,018	$ 121,043	$ 359,007	$ 341,359
Cost of Sales
Total Cost of Sales	56,444	69,943	207,353	208,184
Gross Profit	37,574	51,100	151,654	133,175
Services & Support [Member]
Sales
Total Sales	20,074	19,292	55,267	47,830
Cost of Sales
Total Cost of Sales	11,317	11,944	34,963	32,828
Gross Profit	$ 8,757	$ 7,348	$ 20,304	$ 15,002

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income (Loss)	$ (46,123)	$ 7,589	$ (41,358)	$ (10,895)
Other Comprehensive Loss, net of tax
Net unrealized gains (losses) on available-for-sale securities	(15)	(32)	277	(3,340)
Defined benefit plan adjustments	90	37	361	104
Foreign currency translation	(2,486)	(451)	(3,113)	(3,033)
Other Comprehensive Loss, net of tax	(2,411)	(446)	(2,475)	(6,269)
Comprehensive Income (Loss), net of tax	$ (48,534)	$ 7,143	$ (43,833)	$ (17,164)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2017	$ 497,911	$ 797	$ 260,515	$ 922,178	$ (682,284)	$ (3,295)
Beginning Balance, Shares at Dec. 31, 2017		79,652
Net income (loss)	(10,814)			(10,814)
Adoption of new accounting standards (See Note 1)	3,499			3,499
Other comprehensive income (loss), net of tax	(2,508)					(2,508)
Dividend payments ($0.09 per share)	(4,367)			(4,367)
Dividends accrued on unvested RSUs	(2)			(2)
Stock options exercised	369			(150)	519
PSUs, RSUs and restricted stock vested				(733)	733
Purchases of treasury stock	(10,171)				(10,171)
Stock-based compensation expense	1,819		1,819
Ending Balance at Mar. 31, 2018	475,736	$ 797	262,334	909,611	(691,203)	(5,803)
Ending Balance, Shares at Mar. 31, 2018		79,652
Beginning Balance at Dec. 31, 2017	497,911	$ 797	260,515	922,178	(682,284)	(3,295)
Beginning Balance, Shares at Dec. 31, 2017		79,652
Net income (loss)	(10,895)
Other comprehensive income (loss), net of tax	(6,269)
Ending Balance at Sep. 30, 2018	463,601	$ 797	265,758	900,324	(693,714)	(9,564)
Ending Balance, Shares at Sep. 30, 2018		79,652
Beginning Balance at Mar. 31, 2018	475,736	$ 797	262,334	909,611	(691,203)	(5,803)
Beginning Balance, Shares at Mar. 31, 2018		79,652
Net income (loss)	(7,670)			(7,670)
Other comprehensive income (loss), net of tax	(3,315)					(3,315)
Dividend payments ($0.09 per share)	(4,312)			(4,312)
Dividends accrued on unvested RSUs	7			7
PSUs, RSUs and restricted stock vested				(49)	49
Purchases of treasury stock	(2,603)				(2,603)
Stock-based compensation expense	1,784		1,784
Ending Balance at Jun. 30, 2018	459,627	$ 797	264,118	897,587	(693,757)	(9,118)
Ending Balance, Shares at Jun. 30, 2018		79,652
Net income (loss)	7,589			7,589
Other comprehensive income (loss), net of tax	(446)					(446)
Dividend payments ($0.09 per share)	(4,297)			(4,297)
Dividends accrued on unvested RSUs	(20)			(20)
Stock options exercised	952			(385)	1,337
PSUs, RSUs and restricted stock vested	(32)			(150)	118
Purchases of treasury stock	(1,412)				(1,412)
Stock-based compensation expense	1,640		1,640
Ending Balance at Sep. 30, 2018	463,601	$ 797	265,758	900,324	(693,714)	(9,564)
Ending Balance, Shares at Sep. 30, 2018		79,652
Beginning Balance at Dec. 31, 2018	$ 446,279	$ 797	267,670	883,975	(691,747)	(14,416)
Beginning Balance, Shares at Dec. 31, 2018	79,652	79,652
Net income (loss)	$ 770			770
Adoption of new accounting standards (See Note 1)	4			(381)		385
Other comprehensive income (loss), net of tax	(854)					(854)
Dividend payments ($0.09 per share)	(4,301)			(4,301)
Dividends accrued on unvested RSUs	(18)			(18)
PSUs, RSUs and restricted stock vested	(8)			(865)	857
Purchases of treasury stock	(184)				(184)
Stock-based compensation expense	1,859		1,859
Ending Balance at Mar. 31, 2019	443,547	$ 797	269,529	879,180	(691,074)	(14,885)
Ending Balance, Shares at Mar. 31, 2019		79,652
Beginning Balance at Dec. 31, 2018	$ 446,279	$ 797	267,670	883,975	(691,747)	(14,416)
Beginning Balance, Shares at Dec. 31, 2018	79,652	79,652
Net income (loss)	$ (41,358)
Other comprehensive income (loss), net of tax	(2,475)
Ending Balance at Sep. 30, 2019	$ 394,955	$ 797	272,854	827,783	(689,973)	(16,506)
Ending Balance, Shares at Sep. 30, 2019	79,652	79,652
Beginning Balance at Mar. 31, 2019	$ 443,547	$ 797	269,529	879,180	(691,074)	(14,885)
Beginning Balance, Shares at Mar. 31, 2019		79,652
Net income (loss)	3,995			3,995
Other comprehensive income (loss), net of tax	790					790
Dividend payments ($0.09 per share)	(4,303)			(4,303)
Dividends accrued on unvested RSUs	(34)			(34)
Stock options exercised	526			(208)	734
Stock-based compensation expense	1,454		1,454
Ending Balance at Jun. 30, 2019	445,975	$ 797	270,983	878,630	(690,340)	(14,095)
Ending Balance, Shares at Jun. 30, 2019		79,652
Net income (loss)	(46,123)			(46,123)
Other comprehensive income (loss), net of tax	(2,411)					(2,411)
Dividend payments ($0.09 per share)	(4,304)			(4,304)
Dividends accrued on unvested RSUs	42			42
PSUs, RSUs and restricted stock vested	(95)			(462)	367
Stock-based compensation expense	1,871		1,871
Ending Balance at Sep. 30, 2019	$ 394,955	$ 797	$ 272,854	$ 827,783	$ (689,973)	$ (16,506)
Ending Balance, Shares at Sep. 30, 2019	79,652	79,652

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Statement Of Stockholders Equity [Abstract]
Dividend payments	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (41,358)	$ (10,895)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	13,315	11,952
Asset impairments	3,872
Amortization of net premium (discount) on available-for-sale investments	(86)	(14)
Net gain on long-term investments	(8,195)	(5,400)
Net loss on disposal of property, plant and equipment	58	68
Gain on contingency	(1,230)
Gain on life insurance proceeds	(1,000)
Gain on bargain purchase of a business		(11,322)
Stock-based compensation expense	5,184	5,243
Deferred income taxes	30,421	(20,368)
Changes in operating assets and liabilities:
Accounts receivable, net	7,603	41,166
Other receivables	17,645	(1,842)
Inventory, net	(5,998)	16,543
Prepaid expenses and other assets	(10,071)	8,722
Accounts payable, net	(5,569)	5,223
Accrued expenses and other liabilities	10,564	156
Income tax payable	(5,073)	9,461
Net cash provided by operating activities	10,082	48,693
Cash flows from investing activities:
Purchases of property, plant and equipment	(6,008)	(5,695)
Proceeds from sales and maturities of debt and equity investments	38,561	116,757
Purchases of debt and equity investments	(37,223)	(115,271)
Life insurance proceeds received	1,000
Acquisition of business	13	(7,806)
Net cash used in investing activities	(3,657)	(12,015)
Cash flows from financing activities:
Proceeds from stock option exercises	526	1,321
Purchases of treasury stock	(184)	(14,185)
Dividend payments	(12,908)	(12,976)
Net cash used in financing activities	(12,566)	(25,840)
Net increase (decrease) in cash and cash equivalents	(6,141)	10,838
Effect of exchange rate changes	(2,956)	(3,098)
Cash and cash equivalents, beginning of period	105,504	86,433
Cash and cash equivalents, end of period	96,407	94,173
Supplemental disclosure of non-cash investing activities:
Purchases of property, plant and equipment included in accounts payable	$ 135	$ 355

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying unaudited condensed consolidated financial statements of ADTRAN ® In the opinion of management, all adjustments necessary to fairly state these interim statements have been recorded and are of a normal and recurring nature. The results of operations for an interim period are not necessarily indicative of the results for the full year. The interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in ADTRAN’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the SEC on February 28, 2019 (as amended on September 20, 2019, the “2018 Form 10-K”). Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Our more significant estimates include the excess and obsolete inventory reserves, warranty reserves, customer rebates, determination of the deferred and accrued revenue components of multiple performance obligations sales agreements, estimated costs to complete obligations associated with deferred and accrued revenue, estimated income tax provision and income tax contingencies, the fair value of stock-based compensation, impairment of goodwill, valuation and estimated lives of intangible assets, estimated pension liability, fair value of investments and the evaluation of other-than-temporary declines in the value of investments. Actual amounts could differ significantly from these estimates. During the three months ended June 30, 2019, the Company revised the methodology used in estimating its excess and obsolete inventory reserves. Under the revised methodology, we establish reserves for estimated excess and obsolete inventory equal to the difference between the cost of the inventory and the estimated net realizable value of the inventory based on historical usage, known trends, inventory age, and market conditions. When we dispose of excess and obsolete inventories, the related disposals are charged against the inventory reserves. See Note 8 for additional information. Correction of Immaterial Misstatements During the three months ended June 30, 2019, the Company determined that there was an immaterial misstatement of its excess and obsolete inventory reserves in its previously issued annual and interim financial statements. The Company corrected this misstatement by recognizing a $0.8 million out-of-period adjustment during the three months ended June 30, 2019, which increased its excess and obsolete inventory reserves and cost of goods sold for the period. For the six months ended June 30, 2019, the out-of-period adjustment was a cumulative $0.2 million reduction in the Company’s excess and obsolete inventory reserves and cost of goods sold. In addition, the Company determined that a $1.0 million cash inflow related to an insurance recovery was incorrectly classified as a cash flow from operations instead of a cash flow from investing activities within the unaudited Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2019. The Company has corrected this misstatement in the Unaudited Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2019 to correctly reflect the $1.0 million insurance recovery as a cash inflow from investing activities. Management has determined that these misstatements were not material to any of its previously issued financial statements and that correction of the misstatements is also not material to the current or estimated annual 2019 financial results on either a quantitative and qualitative basis. Recent Accounting Pronouncements Not Yet Adopted In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Codification Improvements to Topic 326 Financial Instruments – Credit Losses, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief, In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement, Fair Value Measurement. Concepts Statement No. 8 — Conceptual Framework for Financial Reporting — Chapter 8 — Notes to Financial Statements In August 2018, the FASB issued ASU 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans, In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement. Recently Adopted Accounting Pronouncements During 2019, we adopted the following accounting standards, which had the following impacts on our consolidated financial statements: In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), Codification Improvements to Topic 842 Leases Leases (Topic 842), Targeted Improvements Leases (Topic 840) Leases (Topic 842) Codification Improvements The Company adopted the new standard on January 1, 2019, the effective date of our initial application, using the optional transition method. At that time, the Company elected to carry forward the legacy ASC 840 disclosures for comparative periods and, therefore, did not adjust the comparative period financial information prior to January 1, 2019. In addition, the Company elected the package of practical expedients which allows for companies to not reassess whether any expired or existing contracts are or contain leases, not reassess historical lease classifications for expired or existing contracts and not reassess initial direct costs for existing leases. Additionally, the Company elected the practical expedients which allow the use of hindsight when determining the lease term, the short-term lease recognition exemption and the option to not separate lease and non-lease components. The adoption of this standard resulted in the recognition of a right-of-use asset and corresponding right-of-use liability on our Condensed Consolidated Balance Sheet of $10.3 million as of January 1, 2019, primarily related to our operating leases for office space, automobiles and other equipment. As a lessee, the adoption of this standard did not have a material impact on our Condensed Consolidated Statement of Income or Statement of Cash Flows. See Note 12 for additional information. As a lessor, the adoption of this standard did not have a material impact on the Company’s Condensed Consolidated Balance Sheet, Condensed Consolidated Statement of Income or Condensed Consolidated Statement of Cash Flows. Prior to and after adoption, all of our leases in which we are the lessor were classified as sales-type leases. In March 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (“SOFR”) Overnight Index Swap (“OIS”) Rate as a Benchmark Interest Rate for Hedge Accounting, In February 2018, the FASB issued ASU 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Comprehensive Income. See Note 13 for additional information.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Business Combinations	2. BUSINESS COMBINATIONS On November 30, 2018, we acquired SmartRG, Inc. (“SmartRG”), a provider of carrier-class, open connected home platforms and cloud services for broadband service providers in exchange for cash consideration. This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. The revenue from the SmartRG portfolio is included in the Subscriber Solutions & Experience category within the Network Solutions and Services & Support reportable segments. Contingent liabilities with a fair value totaling $1.2 million were recognized at the acquisition date, the payments of which were dependent upon SmartRG achieving future revenue, EBIT or customer purchase order milestones during the first half of 2019. The required milestones were not achieved and, therefore, we recognized a gain of $1.2 million upon the reversal of these liabilities during the second quarter of 2019. An escrow in the amount of $2.8 million was set up at the acquisition date to fund post-closing working capital settlements and to satisfy indemnity obligations to the Company arising from any inaccuracy or breach of representations, warranties, covenants, agreements or obligations of the sellers. The escrow is subject to arbitration with final settlement expected during the fourth quarter of 2020. The minimum and maximum potential release of funds to the sellers ranges from zero to $2.8 million. We recorded goodwill of $3.5 million as a result of this acquisition, which represents the excess of the purchase price over the fair value of net assets acquired. We assessed the recognition and measurement of the assets acquired and liabilities assumed based on historical and forecasted data for future periods and concluded that our valuation procedures and resulting measures were appropriate. The final allocation of the purchase price to the estimated fair value of the assets acquired and liabilities assumed at the acquisition date for SmartRG are as follows: (In thousands) Assets Tangible assets acquired $ 8,594 Intangible assets 9,960 Goodwill 3,476 Total assets acquired 22,030 Liabilities Liabilities assumed (6,001 ) Total liabilities assumed (6,001 ) Total purchase price $ 16,029 The details of the acquired intangible assets from the SmartRG acquisition are as follows: (In thousands) Value Life (in years) Developed technology $ 7,400 7 Customer relationships 1,790 3 Licensing agreements 560 5 – 10 Trade name 210 3 Total $ 9,960 For the three and nine months ended September 30, 2019, we incurred acquisition and integration related expenses and On March 19, 2018, we acquired Sumitomo Electric Lightwave Corp.’s North American EPON business and entered into a technology license and OEM supply agreement with Sumitomo Electric Industries, Ltd. This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. This revenue is included in the Access & Aggregation and Subscriber Solutions & Experience categories within the Network Solutions reportable segment. We recorded a bargain purchase gain, net of income taxes, of $11.3 million during the first quarter of 2018, which represents the difference between the fair value of the net assets acquired over the cash paid. We assessed the recognition and measurement of the assets acquired and liabilities assumed based on historical and forecasted data for future periods and concluded that our valuation procedures and resulting measures were appropriate. The following unaudited supplemental pro forma information presents the financial results of the Company for the nine months ended September 30, 2018 as if the acquisition of the Sumitomo EPON business had occurred on January 1, 2018. This unaudited supplemental pro forma information does not purport to be indicative of what would have occurred had the acquisition been completed on January 1, 2018, nor is it indicative of any future results. There were no material, non-recurring adjustments to this unaudited pro forma information. Nine Months Ended (In thousands) September 30, 2018 Pro forma revenue $ 390,449 Pro forma net loss $ (23,431 )

Revenue

Revenue	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Revenue	3. REVENUE The following is a description of the principal activities from which we generate our revenue by reportable segment. Network Solutions Segment Network Solutions includes hardware products and software-defined next-generation virtualized solutions used in service provider or business networks, as well as prior generation products. The majority of the revenue from this segment is from hardware sales. In certain transactions, we are also the lessor in sales-type lease arrangements for network equipment. These arrangements typically include network equipment, network implementation services and maintenance services. Network implementation services and maintenance services are included in the Services & Support segment discussed below. See Note 12 for additional information. Services & Support Segment To complement our Network Solutions segment, we offer a complete portfolio of maintenance, network implementation, solutions integration and managed services, which include hosted cloud services and subscription services. Sales by Category In addition to our reporting segments, we also report revenue in the following three categories – Access & Aggregation, Subscriber Solutions & Experience and Traditional & Other Products. The following table disaggregates our revenue by reportable segment and revenue category for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 48,902 $ 16,212 $ 65,114 $ 76,046 $ 15,855 $ 91,901 Subscriber Solutions & Experience (1) 40,382 2,094 42,476 37,313 1,239 38,552 Traditional & Other Products 4,734 1,768 6,502 7,684 2,198 9,882 Total $ 94,018 $ 20,074 $ 114,092 $ 121,043 $ 19,292 $ 140,335 (1) The following table disaggregates our revenue by reportable segment and revenue category for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 230,837 $ 43,476 $ 274,313 $ 220,653 $ 37,670 $ 258,323 Subscriber Solutions & Experience (1) 113,545 6,186 119,731 99,396 3,817 103,213 Traditional & Other Products 14,625 5,605 20,230 21,310 6,343 27,653 Total $ 359,007 $ 55,267 $ 414,274 $ 341,359 $ 47,830 $ 389,189 (1) Revenue is measured based on the consideration we expect to receive in exchange for transferring goods or providing services to a customer and as performance obligations under the terms of the contract are satisfied. For transactions where there are multiple performance obligations, we account for individual products and services separately if they are distinct (if a product or service is separately identifiable from other items and if a customer can benefit from it on its own or with other resources that are readily available to the customer). As of September 30, 2019, we did not have any significant performance obligations related to customer contracts that had an original expected duration of one year or more, other than maintenance services, which are satisfied over time. The following table provides information about receivables, contract assets and unearned revenue from contracts with customers: (In thousands) September 30, 2019 December 31, 2018 Accounts receivable, net $ 90,647 $ 99,385 Contract assets (1) $ 2,434 $ 3,766 Unearned revenue $ 14,022 $ 17,940 Non-current unearned revenue $ 4,581 $ 5,296 (1) Of the outstanding unearned revenue balance at December 31, 2018, $1.2 million and $11.7 million was recognized as revenue during the three and nine months ended September 30, 2019, respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	4. INCOME TAXES Our effective tax rate increased from a benefit of 34.9%, excluding the tax effect of the bargain purchase gain, in the nine months ended September 30, 2018, to an expense of 197.1% in the nine months ended September 30, 2019. The increase in the effective tax rate between the two periods was primarily driven by the establishment of a valuation allowance against our domestic deferred tax assets in the amount of $37.1 million during the three months ended September 30, 2019, offset by a 9.38% rate reduction related to a transfer pricing study completed during the second quarter of 2019 that resulted in the assignment of operating expenditures to specific company locations, and the effective income tax rates among the respective jurisdictions. As of September 30, 2019, the Company had deferred tax assets totaling $49.4 million. As of September 30, 2019, a valuation allowance totaling $42.9 million has been established against our deferred tax assets. Of this amount, $37.1 million was established during the third quarter of 2019 relating to our domestic deferred tax assets. The remaining $5.8 million that was established in prior periods relates to state research and development credit carryforwards, and foreign net operating loss and research and development credit carryforwards, where we lack sufficient activity to realize those deferred tax assets. The remaining $6.5 million in deferred tax assets not offset by a valuation allowance are located in various foreign jurisdictions where the Company believes it is more likely than not we will realize these deferred tax assets. Supplemental balance sheet information related to deferred tax assets is as follows: September 30, 2019 (In thousands) Deferred Tax Assets Valuation Allowance Deferred Tax Assets, net Domestic $ 40,496 $ (40,496 ) $ — International 8,909 (2,417 ) 6,492 Total $ 49,405 $ (42,913 ) $ 6,492 The Company continually reviews the adequacy of our valuation allowance and recognizes the benefits of deferred tax assets only as the reassessment indicates that it is more likely than not that the deferred tax assets will be realized in accordance with ASC 740, Income Taxes

Pension Benefit Plan

Pension Benefit Plan	9 Months Ended
	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Pension Benefit Plan	5. PENSION BENEFIT PLAN We maintain a defined benefit pension plan covering employees in certain foreign countries. The following table summarizes the components of net periodic pension cost for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Service cost $ 366 $ 294 $ 1,109 $ 905 Interest cost 158 179 479 551 Expected return on plan assets (346 ) (381 ) (1,049 ) (1,174 ) Amortization of actuarial losses 198 61 600 188 Net periodic pension cost $ 376 $ 153 $ 1,139 $ 470 The components of net periodic pension cost, other than the service cost component, are included in other income (expense), net in the Condensed Consolidated Statements of Income. Service cost are included in cost of sales, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Income.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	6. STOCK-BASED COMPENSATION The following table summarizes stock-based compensation expense related to stock options, performance stock units (“PSUs”), restricted stock units (“RSUs”) and restricted stock for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Stock-based compensation expense included in cost of sales $ 83 $ 101 $ 272 $ 298 Selling, general and administrative expense 1,142 894 2,867 2,924 Research and development expense 646 645 2,045 2,021 Stock-based compensation expense included in operating expenses 1,788 1,539 4,912 4,945 Total stock-based compensation expense 1,871 1,640 5,184 5,243 Tax benefit for expense associated with stock options, PSUs, RSUs and restricted stock (446 ) (292 ) (1,235 ) (1,016 ) Total stock-based compensation expense, net of tax $ 1,425 $ 1,348 $ 3,949 $ 4,227 Stock Options The following table is a summary of our stock options outstanding as of December 31, 2018 and September 30, 2019, and the changes that occurred during the nine months ended September 30, 2019: Number of Stock Options (in thousands) Weighted Avg. Exercise Price (per share) Weighted Avg. Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Stock options outstanding, December 31, 2018 4,382 $ 22.91 4.10 $ — Stock options exercised (34 ) $ 15.53 Stock options forfeited (28 ) $ 15.53 Stock options expired (183 ) $ 24.41 Stock options outstanding, September 30, 2019 4,137 $ 22.96 3.27 $ — Stock options exercisable, September 30, 2019 3,915 $ 23.39 3.11 $ — At September 30, 2019, total unrecognized compensation expense related to non-vested stock options was approximately $0.1 million, which is expected to be recognized over an average remaining recognition period of 0.3 years. Unrecognized compensation expense will be adjusted for actual forfeitures. All of the options above were issued at exercise prices that approximated fair market value at the date of grant. The aggregate intrinsic value of stock options represents the total pre-tax intrinsic value (the difference between ADTRAN’s closing stock price on the last trading day of the quarter and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on September 30, 2019. The amount of aggregate intrinsic value will change based on the fair market value of ADTRAN’s stock and was zero as of September 30, 2019. The total pre-tax intrinsic value of options exercised during the nine months ended September 30, 2019 was $0.1 million. The fair value of our stock options is estimated using the Black-Scholes model. The determination of the fair value of stock options on the date of grant using the Black-Scholes model is affected by our stock price, as well as assumptions regarding a number of complex and subjective variables that may have a significant impact on the fair value estimate. These variables include, but are not limited to, the volatility of our stock price and employee exercise behaviors. There were no stock options granted during the three and nine months ended September 30, 2019 and 2018. PSUs, RSUs and Restricted Stock The following table is a summary of our PSUs, RSUs and restricted stock outstanding as of December 31, 2018 and September 30, 2019 and the changes that occurred during the nine months ended September 30, 2019. Number of Shares (in thousands) Weighted Avg. Grant Date Fair Value (per share) Unvested PSUs, RSUs and restricted stock outstanding, December 31, 2018 1,570 $ 18.52 PSUs, RSUs and restricted stock granted 63 $ 12.81 PSUs, RSUs and restricted stock vested (22 ) $ 17.13 PSUs, RSUs and restricted stock forfeited (175 ) $ 18.69 Unvested PSUs, RSUs and restricted stock outstanding, September 30, 2019 1,436 $ 18.27 The fair value of our PSUs with market and performance conditions is calculated using a Monte Carlo simulation valuation method. The fair value of RSUs and restricted stock is equal to the closing price of our stock on the business day immediately preceding the grant date. At September 30, 2019, total unrecognized compensation expense related to the non-vested portion of market-based PSUs, RSUs and restricted stock was approximately $11.6 million, which is expected to be recognized over an average remaining recognition period of 2.4 years. In addition, there was $8.2 million of unrecognized compensation expense related to unvested 2017 performance-based PSUs, which will be recognized over the remaining requisite service period of 0.3 years if achievement of the performance obligation becomes probable. For the three and nine months ended September 30, 2019 and 2018, no compensation expense was recognized related to these 2017 performance-based PSUs. Unrecognized compensation expense will be adjusted for actual forfeitures.

Investments

Investments	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Investments	7. INVESTMENTS Debt Securities and Other Investments At September 30, 2019, we held the following debt securities and other investments, recorded at fair value: Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 10,733 $ 95 $ — $ 10,828 Municipal fixed-rate bonds 931 — (1 ) 930 Asset-backed bonds 7,222 35 (2 ) 7,255 Mortgage/Agency-backed bonds 7,366 29 (7 ) 7,388 U.S. government bonds 9,160 4 (21 ) 9,143 Foreign government bonds 372 — (3 ) 369 Available-for-sale debt securities held at fair value $ 35,784 $ 163 $ (34 ) $ 35,913 At December 31, 2018, we held the following debt securities and other investments, recorded at fair value: Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 20,777 $ 19 $ (112 ) $ 20,684 Municipal fixed-rate bonds 1,339 — (26 ) 1,313 Asset-backed bonds 5,230 5 (14 ) 5,221 Mortgage/Agency-backed bonds 3,833 2 (44 ) 3,791 U.S. government bonds 9,271 1 (66 ) 9,206 Foreign government bonds 592 — (8 ) 584 Available-for-sale debt securities held at fair value $ 41,042 $ 27 $ (270 ) $ 40,799 As of September 30, 2019, our debt securities had the following contractual maturities: (In thousands) Corporate bonds Municipal fixed-rate bonds Asset- backed bonds Mortgage / Agency- backed bonds U.S. government bonds Foreign government bonds Less than one year $ 3,154 $ — $ — $ — $ — $ — One to two years 4,316 930 941 215 — — Two to three years 3,068 — 2,475 1,072 7,528 — Three to five years 290 — 1,593 920 1,615 369 Five to ten years — — 1,666 680 — — More than ten years — — 580 4,501 — — Total $ 10,828 $ 930 $ 7,255 $ 7,388 $ 9,143 $ 369 Actual maturities may differ from contractual maturities as some borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Realized gains and losses on sales of debt securities are computed under the specific identification method. The following table presents gross realized gains and losses related to our debt securities: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Gross realized gains on debt securities $ 36 $ 24 $ 85 $ 49 Gross realized losses on debt securities (7 ) (50 ) (40 ) (365 ) Total gain (loss) recognized, net $ 29 $ (26 ) $ 45 $ (316 ) Our investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio. At September 30, 2019, we held a $25.6 million restricted certificate of deposit that is carried at cost and matures on January 8, 2020. This investment serves as a collateral deposit against the principal amount outstanding under loans made to ADTRAN pursuant to an Alabama State Industrial Development Authority revenue bond (the “Bond”), which totaled $25.6 million at September 30, 2019 and December 31, 2018. At September 30, 2019 and December 31, 2018, the estimated fair value of the Bond using a level 2 valuation technique was approximately $25.6 million and $25.4 million, respectively, based on a debt security with a comparable interest rate and maturity and a Standard and Poor’s credit rating of AA+. We have the right to offset the balance of the Bond with the collateral deposit in order to reduce the balance of the indebtedness. The Bond matures on January 1, 2020, and bears interest at the rate of 2% per annum. In conjunction with this program, we are eligible to receive certain economic incentives from the State of Alabama that reduce the amount of payroll withholdings we are required to remit to the state for those employment positions that qualify under this program. We are required to make payments in the amounts necessary to pay the interest on the amounts currently outstanding. We have made annual principal payments in addition to the interest amounts that are due. The restricted funds held as collateral against the outstanding principal amount of the Bond will be used to pay the outstanding principal and interest upon the Bond’s maturity. Marketable Equity Securities Our marketable equity securities consist of publicly traded stock, funds and certain other investments measured at fair value or cost (where appropriate). On January 1, 2018, we adopted ASU 2016-01, which requires us to measure all equity investments that do not result in consolidation and are not accounted for under the equity method at fair value, with any changes in fair value recognized in net investment gain (loss). Upon adoption, we reclassified $3.2 million of net unrealized gains related to marketable equity securities from accumulated other comprehensive income (loss) to retained earnings. ASU 2016-01 also provides a measurement alternative for equity investments that do not have a readily determinable fair value in which investments can be recorded at cost less impairment, if any, adjusted for observable price changes for an identical or similar investment. We elected to record our equity investment that does not have a readily determinable fair value using the measurement alternative method. As of December 31, 2018, the Company had a note receivable of approximately $4.3 million, which was included in other receivables on the Condensed Consolidated Balance Sheet. During the three months ended March 31, 2019, this amount was repaid and reissued in the form of debt and equity. Approximately $3.4 million was issued as an equity investment, which represented a non-cash investing activity. The carrying value of this investment under the measurement alternative was $3.4 million as of September 30, 2019. The remaining amount, approximately $0.9 million, was converted into a new note receivable, which is included in other receivables on the Condensed Consolidated Balance Sheet and represents a non-cash operating activity. Realized and unrealized gains and losses for our marketable equity securities for the three and nine months ended September 30, 2019 and 2018 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Realized gains (losses) on equity securities sold $ (20 ) $ 1,240 $ (83 ) $ 1,587 Unrealized gains (losses) on equity securities held (225 ) 3,293 8,233 4,129 Total gain (loss) recognized, net $ (245 ) $ 4,533 $ 8,150 $ 5,716 As of September 30, 2019 and 2018, gross unrealized losses related to individual investments in a continuous loss position for twelve months or longer were not material. We have categorized our cash equivalents and our investments held at fair value into a three-level fair value hierarchy based on the priority of the inputs to the valuation technique for the cash equivalents and investments as follows: Level 1 - Values based on unadjusted quoted prices for identical assets or liabilities in an active market; Level 2 - Values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; Level 3 - Values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs include information supplied by investees. Fair Value Measurements at September 30, 2019 Using (In thousands) Fair Value Quoted Prices in Active Market for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents Money market funds $ 1,817 $ 1,817 $ — $ — Commercial paper 1,295 — 1,295 — Cash equivalents 3,112 1,817 1,295 — Available-for-sale debt securities Corporate bonds 10,828 — 10,828 — Municipal fixed-rate bonds 930 — 930 — Asset-backed bonds 7,255 — 7,255 — Mortgage/Agency-backed bonds 7,388 — 7,388 — U.S. government bonds 9,143 9,143 — — Foreign government bonds 369 — 369 — Marketable equity securities Marketable equity securities – various industries 32,543 32,543 — — Equity in escrow 165 165 — — Deferred compensation plan assets 20,580 20,580 — — Total debt and equity securities at fair value 89,201 62,431 26,770 — Total $ 92,313 $ 64,248 $ 28,065 $ — Fair Value Measurements at December 31, 2018 Using (In thousands) Fair Value Quoted Prices in Active Market for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents Money market funds $ 1,554 $ 1,554 $ — $ — Cash equivalents 1,554 1,554 — — Available-for-sale debt securities Corporate bonds 20,684 — 20,684 — Municipal fixed-rate bonds 1,313 — 1,313 — Asset-backed bonds 5,221 — 5,221 — Mortgage/Agency-backed bonds 3,791 — 3,791 — U.S. government bonds 9,206 9,206 — — Foreign government bonds 584 — 584 — Marketable equity securities Marketable equity securities – various industries 26,763 26,763 — — Equity in escrow 253 253 — — Deferred compensation plan assets 18,256 18,256 — — Total debt and equity securities at fair value 86,071 54,478 31,593 — Total $ 87,625 $ 56,032 $ 31,593 $ — The fair value of our Level 2 securities is calculated using a weighted average market price for each security. Market prices are obtained from a variety of industry standard data providers, large financial institutions, and other third-party sources. These multiple market prices are used as inputs into a distribution-curve-based algorithm to determine the daily market value of each security.

Inventory

Inventory	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventory	8. INVENTORY At September 30, 2019 and December 31, 2018, inventory consisted of the following: September 30, December 31, (In thousands) 2019 2018 Raw materials $ 39,133 $ 45,333 Work in process 1,083 1,638 Finished goods 64,725 52,877 Total $ 104,941 $ 99,848 Inventory reserves are established for estimated excess and obsolete inventory equal to the difference between the cost of the inventory and the estimated net realizable value of the inventory based on historical usage, known trends, inventory age, and market conditions. At September 30, 2019 and December 31, 2018, our inventory reserve was $32.0 million and $30.0 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Property, Plant and Equipment	9. PROPERTY, PLANT AND EQUIPMENT At September 30, 2019 and December 31, 2018, property, plant and equipment consisted of the following: September 30, December 31, (In thousands) 2019 2018 Land $ 4,575 $ 4,575 Building and land improvements 34,634 34,379 Building 68,247 68,183 Furniture and fixtures 19,878 19,831 Computer hardware and software 72,390 92,071 Engineering and other equipment 129,479 127,060 Total Property, Plant and Equipment 329,203 346,099 Less accumulated depreciation (255,819 ) (265,464 ) Total Property, Plant and Equipment, net $ 73,384 $ 80,635 Depreciation expense was $3.1 million for the three months ended September 30, 2019 and 2018 and was $9.3 million and $9.5 million for the nine months ended September 30, 2019 and 2018, respectively, which is recorded in cost of sales, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Income. We review long-lived assets used in operations for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. During the three and nine months ended September 30, 2019, the Company recognized impairment charges of $3.9 million related to the abandonment of certain information technology projects in which we had previously capitalized costs related to these projects. The impairment charges were determined based on actual costs incurred as part of the projects.

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2019
Goodwill Disclosure [Abstract]
Goodwill	10. GOODWILL Goodwill, all of which relates to our acquisitions of Bluesocket, Inc. in 2011 and SmartRG in 2018, was $7.0 million and $7.1 million at September 30, 2019 and December 31, 2018, respectively, of which $6.6 million and $0.4 million was allocated to our Network Solutions and Services & Support reportable segments, respectively, as of September 30, 2019, and of which $6.7 million and $0.4 million was allocated to our Network Solutions and Services & Support reportable segments, respectively, as of December 31, 2018. Goodwill related to our SmartRG acquisition was reduced by $0.1 million during the nine months ended September 30, 2019 as a result of a measurement period adjustment. We evaluate the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that would more likely than not reduce the fair value of the reporting unit below its carrying amount. We have elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step impairment test. If we determine that it is more likely than not that its fair value is less than its carrying amount, then the two-step impairment test will be performed. Based on the results of our qualitative assessment in the fourth quarter of 2018 , we concluded that it was not necessary to perform the two-step impairment test. No events or circumstances occurred during the nine months ended September 30, 2019 that would more likely than not reduce the fair value of goodwill below its carrying value.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2019
Intangible Assets Net Excluding Goodwill [Abstract]
Intangible Assets	11. Intangible assets include those acquired in conjunction with several acquisitions since 2011, with the most recent being SmartRG, Inc. in November 2018. The following table presents our intangible assets as of September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 (In thousands) Gross Value Accumulated Amortization Net Value Gross Value Accumulated Amortization Net Value Customer relationships $ 22,235 $ (6,671 ) $ 15,564 $ 22,455 $ (5,380 ) $ 17,075 Developed technology 10,170 (3,094 ) 7,076 12,801 (4,867 ) 7,934 Licensed technology 5,900 (1,011 ) 4,889 5,900 (520 ) 5,380 Supplier relationships 2,800 (2,158 ) 642 2,800 (1,108 ) 1,692 Licensing agreements 560 (61 ) 499 560 (5 ) 555 Patents 500 (209 ) 291 500 (157 ) 343 Trade names 310 (158 ) 152 310 (106 ) 204 Total $ 42,475 $ (13,362 ) $ 29,113 $ 45,326 $ (12,143 ) $ 33,183 Amortization expense was $1.3 million and $0.9 million for the three months ended September 30, 2019 and 2018, respectively, and $4.0 million and $2.4 million for the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019, estimated future amortization expense of our intangible assets was as follows: (In thousands) Amount Remainder of 2019 $ 1,329 2020 4,436 2021 4,088 2022 3,464 2023 3,313 Thereafter 12,483 Total $ 29,113

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	12. LEASES Operating Leases We have operating leases for office space, automobiles, and various other equipment in the United States and in certain international locations in which we do business. We also have other contracts, such as manufacturing agreements and service agreements, which we reviewed to determine if they contain any embedded leases. We specifically reviewed these other contracts to determine whether we have the right to substantially all of the economic benefit from the use of any specified assets or the right to direct the use of any specified assets, either of which would indicate the existence of a lease. As of September 30, 2019, our operating leases have remaining lease terms of two months to six years, some of which include options to extend the leases for up to five years, and some of which include options to terminate the leases within three months Supplemental balance sheet information related to operating leases is as follows: September 30, January 1, (In thousands) Classification 2019 2019 (1) Assets Operating lease asset Other assets $ 18,529 $ 10,322 Total lease assets $ 18,529 $ 10,322 Liabilities Current operating lease liability Accrued expenses $ 3,063 $ 2,948 Non-current operating lease liability Other non-current liabilities 15,659 7,374 Total lease liability $ 18,722 $ 10,322 (1) The components of lease expense included in the Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2019 were as follows: (in thousands) Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Selling, general and administrative expenses $ 352 $ 1,050 Research and development expenses 847 1,731 Cost of sales 16 49 Total operating lease expense $ 1,215 $ 2,830 As of September 30, 2019, operating lease liabilities included on the Condensed Consolidated Balance Sheet by future maturity were as follows: (In thousands) Amount Remainder of 2019 $ 1,044 2020 3,417 2021 3,071 2022 2,672 2023 2,350 Thereafter 8,258 Total lease payments 20,812 Less: Interest (2,090 ) Present value of lease liabilities $ 18,722 Future o perating lease payments include $7.6 million related to options to extend lease terms that are reasonably certain of being exercised. There are no legally binding leases that have not yet commenced A s of December 31, 2018, future minimum rental payments under non-cancelable operating leases, including renewals determined to be reasonably assured as of December 31, 2018, with original maturities of greater than 12 months, were as follows: (In thousands) Amount (1) 2019 $ 3,873 2020 3,580 2021 2,771 2022 2,053 2023 1,317 Thereafter 762 Total $ 14,356 (1) Certain renewal options were subsequently determined to not be reasonably assured of renewal upon the Company’s adoption of the new lease accounting standard on January 1, 2019. Our leases do not provide an implicit borrowing rate and therefore we use an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We used the incremental borrowing rate on January 1, 2019, for operating leases that commenced on or prior to that date. The incremental borrowing rate was determined on a portfolio basis by grouping leases with similar terms as well as grouping leases based on a U.S. dollar or Euro functional currency. The actual rate is then determined based on a credit spread over LIBOR as well as the Bloomberg Curve Matrix for the U.S. Communications section. The following table provides information about our weighted average lease terms and weighted average discount rates as of September 30, 2019: September 30, 2019 Weighted average remaining lease term (years) Operating leases with USD functional currency 8.4 Operating leases with Euro functional currency 4.6 Weighted average discount rate Operating leases with USD functional currency 3.22 % Operating leases with Euro functional currency 1.84 % Supplemental cash flow information related to operating leases is as follows: Nine Months Ended (In thousands) September 30, 2019 Cash paid for amounts included in the measurement of operating lease assets / liabilities Cash used in operating activities related to operating leases $ (775 ) Right-of-use assets obtained in exchange for lease obligations $ 21,418 Sales-Type Lease s We are the lessor in sales-type lease arrangements for network equipment, which have initial terms of up to five years. Our sales-type lease arrangements contain either a provision whereby the network equipment reverts back to us upon the expiration of the lease or a provision that allows the lessee to purchase the network equipment at a bargain purchase amount. In addition, our sales-type lease arrangements do not contain any residual value guarantees or material restrictive covenants. The allocation of the consideration between lease and non-lease components is determined by standalone sales price by component. The net investment in sales-type leases consists of lease receivables less unearned income. Collectability of sales-type leases is evaluated periodically at an individual customer level. At September 30, 2019 and December 31, 2018, we had no allowance for credit losses for our net investment in sales-type leases. As of September 30, 2019 and December 31, 2018, the components of the net investment in sales-type leases were as follows: September 30, December 31, (In thousands) 2019 2018 Current minimum lease payments receivable (1) $ 3,643 $ 11,339 Non-current minimum lease payments receivable (2) 1,073 1,670 Total minimum lease payments receivable 4,716 13,009 Less: Current unearned revenue 445 631 Less: Non-current unearned revenue 210 473 Net investment in sales-type leases $ 4,061 $ 11,905 (1) Included in other receivables on the Condensed Consolidated Balance Sheet. (2) Included in other assets on the Condensed Consolidated Balance Sheet. The components of sales-type lease gross profit recognized at the lease commencement date and interest and dividend income, included in the Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2019, were as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2019 September 30, 2019 Sales - Network Solutions $ 47 $ 1,668 Cost of sales - Network Solutions 25 660 Gross profit $ 22 $ 1,008 Interest and dividend income $ 92 $ 278 As of September 30, 2019, future minimum lease payments to be received from sales-type leases were as follows: (In thousands) Amount Remainder of 2019 $ 2,700 2020 1,162 2021 542 2022 225 2023 83 Thereafter 4 Total $ 4,716

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Stockholders' Equity	13. STOCKHOLDERS’ EQUITY Stock Repurchase Program Since 1997, our Board of Directors has approved multiple share repurchase programs that have authorized repurchases of our common stock, which are implemented through open market or private purchases from time to time as conditions warrant. During the nine months ended September 30, 2019, we repurchased 13,000 shares of our common stock at an average price of $14.06 per share. As of September 30, 2019, we had the authority to purchase an additional 2.5 million shares of our common stock under the current authorization of up to 5.0 million shares. Other Comprehensive Income (Loss) The following tables present the changes in accumulated other comprehensive income (loss), net of tax, by component for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments ASU 2018-02 Adoption (1) Total As of June 30, 2019 $ (271 ) $ (7,770 ) $ (6,439 ) $ 385 $ (14,095 ) Other comprehensive loss before reclassifications (39 ) — (2,486 ) — (2,525 ) Amounts reclassified from accumulated other comprehensive income (loss) 24 90 — — 114 Net current period other comprehensive income (loss) (15 ) 90 (2,486 ) — (2,411 ) As of September 30, 2019 $ (286 ) $ (7,680 ) $ (8,925 ) $ 385 $ (16,506 ) (1) Three Months Ended September 30, 2018 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments Total As of June 30, 2018 $ (741 ) $ (4,219 ) $ (4,158 ) $ (9,118 ) Other comprehensive income (loss) before reclassifications 1,208 — (451 ) 757 Amounts reclassified from accumulated other comprehensive income (loss) (1,240 ) 37 — (1,203 ) Net current period other comprehensive income (loss) (32 ) 37 (451 ) (446 ) As of September 30, 2018 $ (773 ) $ (4,182 ) $ (4,609 ) $ (9,564 ) The following tables present the changes in accumulated other comprehensive income (loss), net of tax, by component for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30, 2019 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments ASU 2018-02 Adoption (1) Total As of December 31, 2018 $ (563 ) $ (8,041 ) $ (5,812 ) $ — $ (14,416 ) Other comprehensive income (loss) before reclassifications 372 — (3,113 ) — (2,741 ) Amounts reclassified from accumulated other comprehensive income (loss) (95 ) 361 — — 266 Amounts reclassified to retained earnings (1) — — — 385 385 Net current period other comprehensive income (loss) 277 361 (3,113 ) 385 (2,090 ) As of September 30, 2019 $ (286 ) $ (7,680 ) $ (8,925 ) $ 385 $ (16,506 ) (1) Nine Months Ended September 30, 2018 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments Total As of December 31, 2017 $ 2,567 $ (4,286 ) $ (1,576 ) $ (3,295 ) Other comprehensive income (loss) before reclassifications 869 — (3,033 ) (2,164 ) Amounts reclassified from accumulated other comprehensive income (loss) (989 ) 104 — (885 ) Amounts reclassified to retained earnings (1) (3,220 ) — — (3,220 ) Net current period other comprehensive income (loss) (3,340 ) 104 (3,033 ) (6,269 ) As of September 30, 2018 $ (773 ) $ (4,182 ) $ (4,609 ) $ (9,564 ) (1) The following tables present the details of reclassifications out of accumulated other comprehensive income (loss) for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized losses on sales of securities $ (32 ) Net investment gain Defined benefit plan adjustments – actuarial losses (130 ) (1) Total reclassifications for the period, before tax (162 ) Tax benefit 48 Total reclassifications for the period, net of tax $ (114 ) (1) Three Months Ended September 30, 2018 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 1,676 Net investment gain Defined benefit plan adjustments – actuarial losses (54 ) (1) Total reclassifications for the period, before tax 1,622 Tax expense (419 ) Total reclassifications for the period, net of tax $ 1,203 (1) The following tables present the details of reclassifications out of accumulated other comprehensive income (loss) for the nine months ended September 30, 2019 and 2018: Nine Months Ended September 30, 2019 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 128 Net investment gain Defined benefit plan adjustments – actuarial losses (523 ) (1) Total reclassifications for the period, before tax (395 ) Tax benefit 129 Total reclassifications for the period, net of tax $ (266 ) (1) Nine Months Ended September 30, 2018 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 1,352 Net investment gain Defined benefit plan adjustments – actuarial losses (151 ) (1) Total reclassifications for the period, before tax 1,201 Tax expense (316 ) Total reclassifications for the period, net of tax $ 885 (1) The following table presents the tax effects related to the change in each component of other comprehensive income (loss) for the three months ended September 30, 2019 and 2018: Three Months Ended Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Unrealized gain (loss) on available-for-sale securities $ (53 ) $ 14 $ (39 ) $ 1,632 $ (424 ) $ 1,208 Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss) 32 (8 ) 24 (1,676 ) 436 (1,240 ) Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss) 130 (40 ) 90 54 (17 ) 37 Foreign currency translation adjustment (2,486 ) — (2,486 ) (451 ) — (451 ) Total Other Comprehensive Loss $ (2,377 ) $ (34 ) $ (2,411 ) $ (441 ) $ (5 ) $ (446 ) The following table presents the tax effects related to the change in each component of other comprehensive income (loss) for the nine months ended September 30, 2019 and 2018: Nine Months Ended Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Unrealized gain (loss) on available-for-sale securities $ 503 $ (131 ) $ 372 $ 1,174 $ (305 ) $ 869 Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss) (128 ) 33 (95 ) (1,352 ) 363 (989 ) Reclassification adjustment for amounts reclassed to retained earnings related to the adoption of ASU 2016-01 — — — (3,220 ) — (3,220 ) Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss) 523 (162 ) 361 151 (47 ) 104 Foreign currency translation adjustment (3,113 ) — (3,113 ) (3,033 ) — (3,033 ) Total Other Comprehensive Income (Loss) $ (2,215 ) $ (260 ) $ (2,475 ) $ (6,280 ) $ 11 $ (6,269 )

Earnings (Loss) Per Share

Earnings (Loss) Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	14. EARNINGS (LOSS) PER SHARE A summary of the calculation of basic and diluted earnings (loss) per share for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands, except per share amounts) 2019 2018 2019 2018 Numerator Net income (loss) $ (46,123 ) $ 7,589 $ (41,358 ) $ (10,895 ) Denominator Weighted average number of shares – basic 47,824 47,710 47,803 47,927 Effect of dilutive securities Stock options — 27 — — PSUs, RSUs and restricted stock — 97 — — Weighted average number of shares – diluted 47,824 47,834 47,803 47,927 Earnings (loss) per share – basic $ (0.96 ) $ 0.16 $ (0.87 ) $ (0.23 ) Earnings (loss) per share – diluted $ (0.96 ) $ 0.16 $ (0.87 ) $ (0.23 ) For the three months ended September 30, 2018, 1.8 million stock options were outstanding but were not included in the computation of diluted earnings per share. These stock options were excluded because their exercise prices were greater than the average market price of the common shares, during the quarter, therefore making them anti-dilutive under the treasury stock method. As a result of the net loss for the three months ended September 30, 2019, and for the nine months ended September 30, 2019 and 2018, 4.1 million, 3.0 million and 2.3 million, respectively, shares of unvested stock options, PSUs, RSUs and restricted stock were excluded from the calculation of diluted EPS due to their anti-dilutive effect.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	15. SEGMENT INFORMATION We operate in two reportable segments: (1) Network Solutions and (2) Services & Support. Network Solutions includes hardware products and software defined next-generation virtualized solutions used in service provider or business networks, as well as prior-generation products. Services & Support includes our suite of ProCloud managed services, network installation, engineering and maintenance services and fee-based technical support and equipment repair/replacement plans. We evaluate the performance of our segments based on gross profit; therefore, selling, general and administrative expenses, research and development expenses, interest and dividend income, interest expense, net investment gain (loss), other income (expense) and (provision) benefit for income taxes are reported on a company-wide, functional basis only. There is no inter-segment revenue. The following table presents information about the sales and gross profit of our reportable segments for the three and nine months ended September 30, 2019 and 2018. We do not produce asset information by reportable segment; therefore, it is not reported. Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Sales Gross Profit Sales Gross Profit Network Solutions $ 94,018 $ 37,574 $ 121,043 $ 51,100 Services & Support 20,074 8,757 19,292 7,348 Total $ 114,092 $ 46,331 $ 140,335 $ 58,448 Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Sales Gross Profit Sales Gross Profit Network Solutions $ 359,007 $ 151,654 $ 341,359 $ 133,175 Services & Support 55,267 20,304 47,830 15,002 Total $ 414,274 $ 171,958 $ 389,189 $ 148,177 Sales by Category In addition to our reporting segments, we also report revenue for the following three categories – Access & Aggregation, Subscriber Solutions & Experience (formerly Customer Devices) and Traditional & Other Products. The table below presents sales information by category for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Access & Aggregation $ 65,114 $ 91,901 $ 274,313 $ 258,323 Subscriber Solutions & Experience 42,476 38,552 119,731 103,213 Traditional & Other Products 6,502 9,882 20,230 27,653 Total $ 114,092 $ 140,335 $ 414,274 $ 389,189 The following table represents sales information by geographic area for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 United States $ 83,144 $ 83,730 $ 230,960 $ 214,039 International 30,948 56,605 183,314 175,150 Total $ 114,092 $ 140,335 $ 414,274 $ 389,189

Liability for Warranty Returns

Liability for Warranty Returns	9 Months Ended
	Sep. 30, 2019
Product Warranties Disclosures [Abstract]
Liability for Warranty Returns	16. LIABILITY FOR WARRANTY RETURNS Our products generally include warranties of 90 days to five years for product defects. We accrue for warranty returns at the time revenue is recognized based on our estimate of the cost to repair or replace the defective products. We engage in extensive product quality programs and processes, including actively monitoring and evaluating the quality of our component suppliers. Our products continue to become more complex in both size and functionality as many of our product offerings migrate from line card applications to total systems. The increasing complexity of our products will cause warranty incidences, when they arise, to be more costly. Our estimates regarding future warranty obligations may change due to product failure rates, material usage and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should our actual experience relative to these factors be worse than our estimates, we will be required to record additional warranty expense. Alternatively, if we provide for more reserves than we require, we will reverse a portion of such provisions in future periods. The liability for warranty obligations totaled $8.7 million and $8.6 million at September 30, 2019 and December 31, 2018, respectively, which amounts are included in accrued expenses in the accompanying Condensed Consolidated Balance Sheets. During the three months ended September 30, 2018, we had a reversal of prior provisions, the impact of which is reflected in the table below. A reconciliation of the beginning and ending warranty accrual for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Balance at beginning of period $ 8,972 $ 10,111 $ 8,623 $ 9,724 Plus: Amounts charged to cost and expenses 816 (34 ) 3,796 6,649 Less: Deductions (1,131 ) (1,053 ) (3,762 ) (7,349 ) Balance at end of period $ 8,657 $ 9,024 $ 8,657 $ 9,024

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	17. COMMITMENTS AND CONTINGENCIES Securities Class Action Lawsuit On October 17, 2019, a purported stockholder class action lawsuit, captioned Burbridge v. ADTRAN, Inc. et al. Other Legal Matters In addition to the litigation described above, from time to time we are subject to or otherwise involved in various lawsuits, claims, investigations and legal proceedings that arise out of or are incidental to the conduct of our business (collectively, “Legal Matters”), including those relating to employment matters, patent rights, regulatory compliance matters, stockholder claims, and contractual and other commercial disputes. Such Legal Matters, even if not meritorious, could result in the expenditure of significant financial and managerial resources. Additionally, an unfavorable outcome in a legal matter, including in a patent dispute, could require the Company to pay damages, entitle claimants to other relief, such as royalties, or could prevent the Company from selling some of its products in certain jurisdictions. While the Company cannot predict with certainty the results of the Legal Matters in which it is currently involved, the Company does not expect that the ultimate outcome of such Legal Matters will individually or in the aggregate have a material adverse effect on its business, results of operations, financial condition or cash flows. Investment Commitment We have committed to invest up to an aggregate of $7.9 million in two private equity funds, of which $7.7 million has been applied as of September 30, 2019.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2019
Restructuring And Related Activities [Abstract]
Restructuring	18. RESTRUCTURING In October 2019, the Company announced its plans to reduce its operating expenses, including global restructuring. During the three and nine months ended September 30, 2019, the Company incurred approximately $1.1 million and $1.9 million, respectively, related to these plans. In February 2019, we announced the restructuring of certain of our workforce predominantly in Germany, which included the closure of our office location in Munich, Germany accompanied by relocation or severance benefits for the affected employees. We also offered voluntary early retirement to certain other employees, which was announced in March 2019. The restructuring is expected to be completed in the fourth quarter of 2019. In January 2018, we announced an early retirement incentive program for employees that met certain requirements. The cumulative amount incurred during the year ended December 31, 2018 related to this restructuring program was $7.3 million, of which $0.3 million and $7.2 million was incurred during the three and nine months ended September 30, 2018, respectively. We do not expect to incur any additional expenses related to this restructuring program. A reconciliation of the beginning and ending restructuring liability, which is included in accrued wages and benefits in the Condensed Consolidated Balance Sheets, is as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2019 September 30, 2019 Balance at beginning of period $ 2,655 $ 185 Plus: Amounts charged to cost and expense 1,195 4,658 Less: Amounts paid (252 ) (1,245 ) Balance at end of period $ 3,598 $ 3,598 The components of restructuring expense in the Condensed Consolidated Statements of Income are as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Selling, general and administrative expenses $ 531 $ 261 $ 2,078 $ 2,661 Research and development expenses 602 — 1,833 1,814 Cost of sales 62 — 747 2,761 Total restructuring expenses $ 1,195 $ 261 $ 4,658 $ 7,236 The following table represents the components of restructuring expense by geographic area for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Domestic $ 1,116 $ 256 $ 1,941 $ 7,096 International 79 5 2,717 140 Total restructuring expenses $ 1,195 $ 261 $ 4,658 $ 7,236

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	19. SUBSEQUENT EVENTS On October 30, 2019, we announced that our Board of Directors declared a quarterly cash dividend of $0.09 per common share to be paid to the Company’s stockholders of record as of the close of business on November 14, 2019. The payment date will be December 2, 2019 in the aggregate amount of approximately $4.3 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of ADTRAN ® In the opinion of management, all adjustments necessary to fairly state these interim statements have been recorded and are of a normal and recurring nature. The results of operations for an interim period are not necessarily indicative of the results for the full year. The interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in ADTRAN’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the SEC on February 28, 2019 (as amended on September 20, 2019, the “2018 Form 10-K”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Our more significant estimates include the excess and obsolete inventory reserves, warranty reserves, customer rebates, determination of the deferred and accrued revenue components of multiple performance obligations sales agreements, estimated costs to complete obligations associated with deferred and accrued revenue, estimated income tax provision and income tax contingencies, the fair value of stock-based compensation, impairment of goodwill, valuation and estimated lives of intangible assets, estimated pension liability, fair value of investments and the evaluation of other-than-temporary declines in the value of investments. Actual amounts could differ significantly from these estimates. During the three months ended June 30, 2019, the Company revised the methodology used in estimating its excess and obsolete inventory reserves. Under the revised methodology, we establish reserves for estimated excess and obsolete inventory equal to the difference between the cost of the inventory and the estimated net realizable value of the inventory based on historical usage, known trends, inventory age, and market conditions. When we dispose of excess and obsolete inventories, the related disposals are charged against the inventory reserves. See Note 8 for additional information.
Correction of Immaterial Misstatements	Correction of Immaterial Misstatements During the three months ended June 30, 2019, the Company determined that there was an immaterial misstatement of its excess and obsolete inventory reserves in its previously issued annual and interim financial statements. The Company corrected this misstatement by recognizing a $0.8 million out-of-period adjustment during the three months ended June 30, 2019, which increased its excess and obsolete inventory reserves and cost of goods sold for the period. For the six months ended June 30, 2019, the out-of-period adjustment was a cumulative $0.2 million reduction in the Company’s excess and obsolete inventory reserves and cost of goods sold. In addition, the Company determined that a $1.0 million cash inflow related to an insurance recovery was incorrectly classified as a cash flow from operations instead of a cash flow from investing activities within the unaudited Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2019. The Company has corrected this misstatement in the Unaudited Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2019 to correctly reflect the $1.0 million insurance recovery as a cash inflow from investing activities. Management has determined that these misstatements were not material to any of its previously issued financial statements and that correction of the misstatements is also not material to the current or estimated annual 2019 financial results on either a quantitative and qualitative basis.
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Codification Improvements to Topic 326 Financial Instruments – Credit Losses, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief, In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement, Fair Value Measurement. Concepts Statement No. 8 — Conceptual Framework for Financial Reporting — Chapter 8 — Notes to Financial Statements In August 2018, the FASB issued ASU 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans, In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements During 2019, we adopted the following accounting standards, which had the following impacts on our consolidated financial statements: In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), Codification Improvements to Topic 842 Leases Leases (Topic 842), Targeted Improvements Leases (Topic 840) Leases (Topic 842) Codification Improvements The Company adopted the new standard on January 1, 2019, the effective date of our initial application, using the optional transition method. At that time, the Company elected to carry forward the legacy ASC 840 disclosures for comparative periods and, therefore, did not adjust the comparative period financial information prior to January 1, 2019. In addition, the Company elected the package of practical expedients which allows for companies to not reassess whether any expired or existing contracts are or contain leases, not reassess historical lease classifications for expired or existing contracts and not reassess initial direct costs for existing leases. Additionally, the Company elected the practical expedients which allow the use of hindsight when determining the lease term, the short-term lease recognition exemption and the option to not separate lease and non-lease components. The adoption of this standard resulted in the recognition of a right-of-use asset and corresponding right-of-use liability on our Condensed Consolidated Balance Sheet of $10.3 million as of January 1, 2019, primarily related to our operating leases for office space, automobiles and other equipment. As a lessee, the adoption of this standard did not have a material impact on our Condensed Consolidated Statement of Income or Statement of Cash Flows. See Note 12 for additional information. As a lessor, the adoption of this standard did not have a material impact on the Company’s Condensed Consolidated Balance Sheet, Condensed Consolidated Statement of Income or Condensed Consolidated Statement of Cash Flows. Prior to and after adoption, all of our leases in which we are the lessor were classified as sales-type leases. In March 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (“SOFR”) Overnight Index Swap (“OIS”) Rate as a Benchmark Interest Rate for Hedge Accounting, In February 2018, the FASB issued ASU 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Comprehensive Income. See Note 13 for additional information.

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Final Allocation of the Purchase Price to the Estimated Fair Value of the Assets Acquired and Liabilities Assumed	The final allocation of the purchase price to the estimated fair value of the assets acquired and liabilities assumed at the acquisition date for SmartRG are as follows: (In thousands) Assets Tangible assets acquired $ 8,594 Intangible assets 9,960 Goodwill 3,476 Total assets acquired 22,030 Liabilities Liabilities assumed (6,001 ) Total liabilities assumed (6,001 ) Total purchase price $ 16,029
Details of the Acquired Intangible Assets	The details of the acquired intangible assets from the SmartRG acquisition are as follows: (In thousands) Value Life (in years) Developed technology $ 7,400 7 Customer relationships 1,790 3 Licensing agreements 560 5 – 10 Trade name 210 3 Total $ 9,960
Summary of Unaudited Supplemental Pro Forma Information	The following unaudited supplemental pro forma information presents the financial results of the Company for the nine months ended September 30, 2018 as if the acquisition of the Sumitomo EPON business had occurred on January 1, 2018. This unaudited supplemental pro forma information does not purport to be indicative of what would have occurred had the acquisition been completed on January 1, 2018, nor is it indicative of any future results. There were no material, non-recurring adjustments to this unaudited pro forma information. Nine Months Ended (In thousands) September 30, 2018 Pro forma revenue $ 390,449 Pro forma net loss $ (23,431 )

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Disaggregate of Revenue by Reportable Segment and Revenue Category	The following table disaggregates our revenue by reportable segment and revenue category for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 48,902 $ 16,212 $ 65,114 $ 76,046 $ 15,855 $ 91,901 Subscriber Solutions & Experience (1) 40,382 2,094 42,476 37,313 1,239 38,552 Traditional & Other Products 4,734 1,768 6,502 7,684 2,198 9,882 Total $ 94,018 $ 20,074 $ 114,092 $ 121,043 $ 19,292 $ 140,335 (1) The following table disaggregates our revenue by reportable segment and revenue category for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 230,837 $ 43,476 $ 274,313 $ 220,653 $ 37,670 $ 258,323 Subscriber Solutions & Experience (1) 113,545 6,186 119,731 99,396 3,817 103,213 Traditional & Other Products 14,625 5,605 20,230 21,310 6,343 27,653 Total $ 359,007 $ 55,267 $ 414,274 $ 341,359 $ 47,830 $ 389,189 (1) The table below presents sales information by category for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Access & Aggregation $ 65,114 $ 91,901 $ 274,313 $ 258,323 Subscriber Solutions & Experience 42,476 38,552 119,731 103,213 Traditional & Other Products 6,502 9,882 20,230 27,653 Total $ 114,092 $ 140,335 $ 414,274 $ 389,189
Information about Receivables, Contract Assets, and Unearned Revenue from Contracts with Customers	The following table provides information about receivables, contract assets and unearned revenue from contracts with customers: (In thousands) September 30, 2019 December 31, 2018 Accounts receivable, net $ 90,647 $ 99,385 Contract assets (1) $ 2,434 $ 3,766 Unearned revenue $ 14,022 $ 17,940 Non-current unearned revenue $ 4,581 $ 5,296 (1)

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Summary of Supplemental Balance Sheet Information Related to Deferred Tax Assets	Supplemental balance sheet information related to deferred tax assets is as follows: September 30, 2019 (In thousands) Deferred Tax Assets Valuation Allowance Deferred Tax Assets, net Domestic $ 40,496 $ (40,496 ) $ — International 8,909 (2,417 ) 6,492 Total $ 49,405 $ (42,913 ) $ 6,492

Pension Benefit Plan (Tables)

Pension Benefit Plan (Tables)	9 Months Ended
	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Summarization of Components of Net Periodic Pension Cost	The following table summarizes the components of net periodic pension cost for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Service cost $ 366 $ 294 $ 1,109 $ 905 Interest cost 158 179 479 551 Expected return on plan assets (346 ) (381 ) (1,049 ) (1,174 ) Amortization of actuarial losses 198 61 600 188 Net periodic pension cost $ 376 $ 153 $ 1,139 $ 470

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Expense Related to Stock Options, Performance Stock Units (PSUs), Restricted Stock Units (RSUs) and Restricted Stock	The following table summarizes stock-based compensation expense related to stock options, performance stock units (“PSUs”), restricted stock units (“RSUs”) and restricted stock for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Stock-based compensation expense included in cost of sales $ 83 $ 101 $ 272 $ 298 Selling, general and administrative expense 1,142 894 2,867 2,924 Research and development expense 646 645 2,045 2,021 Stock-based compensation expense included in operating expenses 1,788 1,539 4,912 4,945 Total stock-based compensation expense 1,871 1,640 5,184 5,243 Tax benefit for expense associated with stock options, PSUs, RSUs and restricted stock (446 ) (292 ) (1,235 ) (1,016 ) Total stock-based compensation expense, net of tax $ 1,425 $ 1,348 $ 3,949 $ 4,227
Summary of Stock Options Outstanding	The following table is a summary of our stock options outstanding as of December 31, 2018 and September 30, 2019, and the changes that occurred during the nine months ended September 30, 2019: Number of Stock Options (in thousands) Weighted Avg. Exercise Price (per share) Weighted Avg. Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Stock options outstanding, December 31, 2018 4,382 $ 22.91 4.10 $ — Stock options exercised (34 ) $ 15.53 Stock options forfeited (28 ) $ 15.53 Stock options expired (183 ) $ 24.41 Stock options outstanding, September 30, 2019 4,137 $ 22.96 3.27 $ — Stock options exercisable, September 30, 2019 3,915 $ 23.39 3.11 $ —
Summary of PSUs, RSUs and Restricted Stock Outstanding	The following table is a summary of our PSUs, RSUs and restricted stock outstanding as of December 31, 2018 and September 30, 2019 and the changes that occurred during the nine months ended September 30, 2019. Number of Shares (in thousands) Weighted Avg. Grant Date Fair Value (per share) Unvested PSUs, RSUs and restricted stock outstanding, December 31, 2018 1,570 $ 18.52 PSUs, RSUs and restricted stock granted 63 $ 12.81 PSUs, RSUs and restricted stock vested (22 ) $ 17.13 PSUs, RSUs and restricted stock forfeited (175 ) $ 18.69 Unvested PSUs, RSUs and restricted stock outstanding, September 30, 2019 1,436 $ 18.27

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Debt Securities and Other Investments, Recorded at Fair Value	Debt Securities and Other Investments At September 30, 2019, we held the following debt securities and other investments, recorded at fair value: Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 10,733 $ 95 $ — $ 10,828 Municipal fixed-rate bonds 931 — (1 ) 930 Asset-backed bonds 7,222 35 (2 ) 7,255 Mortgage/Agency-backed bonds 7,366 29 (7 ) 7,388 U.S. government bonds 9,160 4 (21 ) 9,143 Foreign government bonds 372 — (3 ) 369 Available-for-sale debt securities held at fair value $ 35,784 $ 163 $ (34 ) $ 35,913 At December 31, 2018, we held the following debt securities and other investments, recorded at fair value: Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 20,777 $ 19 $ (112 ) $ 20,684 Municipal fixed-rate bonds 1,339 — (26 ) 1,313 Asset-backed bonds 5,230 5 (14 ) 5,221 Mortgage/Agency-backed bonds 3,833 2 (44 ) 3,791 U.S. government bonds 9,271 1 (66 ) 9,206 Foreign government bonds 592 — (8 ) 584 Available-for-sale debt securities held at fair value $ 41,042 $ 27 $ (270 ) $ 40,799
Contractual Maturities of Debt Securities	As of September 30, 2019, our debt securities had the following contractual maturities: (In thousands) Corporate bonds Municipal fixed-rate bonds Asset- backed bonds Mortgage / Agency- backed bonds U.S. government bonds Foreign government bonds Less than one year $ 3,154 $ — $ — $ — $ — $ — One to two years 4,316 930 941 215 — — Two to three years 3,068 — 2,475 1,072 7,528 — Three to five years 290 — 1,593 920 1,615 369 Five to ten years — — 1,666 680 — — More than ten years — — 580 4,501 — — Total $ 10,828 $ 930 $ 7,255 $ 7,388 $ 9,143 $ 369
Gross Realized Gains and Losses on Sale of Debt Securities	The following table presents gross realized gains and losses related to our debt securities: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Gross realized gains on debt securities $ 36 $ 24 $ 85 $ 49 Gross realized losses on debt securities (7 ) (50 ) (40 ) (365 ) Total gain (loss) recognized, net $ 29 $ (26 ) $ 45 $ (316 )
Realized and Unrealized Gains and Losses for Marketable Equity Securities	Realized and unrealized gains and losses for our marketable equity securities for the three and nine months ended September 30, 2019 and 2018 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Realized gains (losses) on equity securities sold $ (20 ) $ 1,240 $ (83 ) $ 1,587 Unrealized gains (losses) on equity securities held (225 ) 3,293 8,233 4,129 Total gain (loss) recognized, net $ (245 ) $ 4,533 $ 8,150 $ 5,716
Fair Value Measurements of Cash Equivalents and Investments	We have categorized our cash equivalents and our investments held at fair value into a three-level fair value hierarchy based on the priority of the inputs to the valuation technique for the cash equivalents and investments as follows: Level 1 - Values based on unadjusted quoted prices for identical assets or liabilities in an active market; Level 2 - Values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; Level 3 - Values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs include information supplied by investees. Fair Value Measurements at September 30, 2019 Using (In thousands) Fair Value Quoted Prices in Active Market for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents Money market funds $ 1,817 $ 1,817 $ — $ — Commercial paper 1,295 — 1,295 — Cash equivalents 3,112 1,817 1,295 — Available-for-sale debt securities Corporate bonds 10,828 — 10,828 — Municipal fixed-rate bonds 930 — 930 — Asset-backed bonds 7,255 — 7,255 — Mortgage/Agency-backed bonds 7,388 — 7,388 — U.S. government bonds 9,143 9,143 — — Foreign government bonds 369 — 369 — Marketable equity securities Marketable equity securities – various industries 32,543 32,543 — — Equity in escrow 165 165 — — Deferred compensation plan assets 20,580 20,580 — — Total debt and equity securities at fair value 89,201 62,431 26,770 — Total $ 92,313 $ 64,248 $ 28,065 $ — Fair Value Measurements at December 31, 2018 Using (In thousands) Fair Value Quoted Prices in Active Market for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash equivalents Money market funds $ 1,554 $ 1,554 $ — $ — Cash equivalents 1,554 1,554 — — Available-for-sale debt securities Corporate bonds 20,684 — 20,684 — Municipal fixed-rate bonds 1,313 — 1,313 — Asset-backed bonds 5,221 — 5,221 — Mortgage/Agency-backed bonds 3,791 — 3,791 — U.S. government bonds 9,206 9,206 — — Foreign government bonds 584 — 584 — Marketable equity securities Marketable equity securities – various industries 26,763 26,763 — — Equity in escrow 253 253 — — Deferred compensation plan assets 18,256 18,256 — — Total debt and equity securities at fair value 86,071 54,478 31,593 — Total $ 87,625 $ 56,032 $ 31,593 $ —

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Components of Inventory	At September 30, 2019 and December 31, 2018, inventory consisted of the following: September 30, December 31, (In thousands) 2019 2018 Raw materials $ 39,133 $ 45,333 Work in process 1,083 1,638 Finished goods 64,725 52,877 Total $ 104,941 $ 99,848

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Property, Plant and Equipment	At September 30, 2019 and December 31, 2018, property, plant and equipment consisted of the following: September 30, December 31, (In thousands) 2019 2018 Land $ 4,575 $ 4,575 Building and land improvements 34,634 34,379 Building 68,247 68,183 Furniture and fixtures 19,878 19,831 Computer hardware and software 72,390 92,071 Engineering and other equipment 129,479 127,060 Total Property, Plant and Equipment 329,203 346,099 Less accumulated depreciation (255,819 ) (265,464 ) Total Property, Plant and Equipment, net $ 73,384 $ 80,635

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Intangible Assets Net Excluding Goodwill [Abstract]
Summary of Intangible Assets	The following table presents our intangible assets as of September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 (In thousands) Gross Value Accumulated Amortization Net Value Gross Value Accumulated Amortization Net Value Customer relationships $ 22,235 $ (6,671 ) $ 15,564 $ 22,455 $ (5,380 ) $ 17,075 Developed technology 10,170 (3,094 ) 7,076 12,801 (4,867 ) 7,934 Licensed technology 5,900 (1,011 ) 4,889 5,900 (520 ) 5,380 Supplier relationships 2,800 (2,158 ) 642 2,800 (1,108 ) 1,692 Licensing agreements 560 (61 ) 499 560 (5 ) 555 Patents 500 (209 ) 291 500 (157 ) 343 Trade names 310 (158 ) 152 310 (106 ) 204 Total $ 42,475 $ (13,362 ) $ 29,113 $ 45,326 $ (12,143 ) $ 33,183
Estimated Future Amortization Expense Related to Intangible Assets	As of September 30, 2019, estimated future amortization expense of our intangible assets was as follows: (In thousands) Amount Remainder of 2019 $ 1,329 2020 4,436 2021 4,088 2022 3,464 2023 3,313 Thereafter 12,483 Total $ 29,113

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information Related to Operating Leases	Supplemental balance sheet information related to operating leases is as follows: September 30, January 1, (In thousands) Classification 2019 2019 (1) Assets Operating lease asset Other assets $ 18,529 $ 10,322 Total lease assets $ 18,529 $ 10,322 Liabilities Current operating lease liability Accrued expenses $ 3,063 $ 2,948 Non-current operating lease liability Other non-current liabilities 15,659 7,374 Total lease liability $ 18,722 $ 10,322 (1)
Components of Lease Expense included in Condensed Consolidated Statement of Income	The components of lease expense included in the Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2019 were as follows: (in thousands) Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Selling, general and administrative expenses $ 352 $ 1,050 Research and development expenses 847 1,731 Cost of sales 16 49 Total operating lease expense $ 1,215 $ 2,830
Schedule of Maturity of Operating Lease Liabilities	As of September 30, 2019, operating lease liabilities included on the Condensed Consolidated Balance Sheet by future maturity were as follows: (In thousands) Amount Remainder of 2019 $ 1,044 2020 3,417 2021 3,071 2022 2,672 2023 2,350 Thereafter 8,258 Total lease payments 20,812 Less: Interest (2,090 ) Present value of lease liabilities $ 18,722
Future Minimum Rental Payments under Non-Cancelable Operating Leases, Including Renewals Determined to be Reasonably Assured, with Original Maturities of Greater than 12 Months	A s of December 31, 2018, future minimum rental payments under non-cancelable operating leases, including renewals determined to be reasonably assured as of December 31, 2018, with original maturities of greater than 12 months, were as follows: (In thousands) Amount (1) 2019 $ 3,873 2020 3,580 2021 2,771 2022 2,053 2023 1,317 Thereafter 762 Total $ 14,356 (1) Certain renewal options were subsequently determined to not be reasonably assured of renewal upon the Company’s adoption of the new lease accounting standard on January 1, 2019.
Schedule of Weighted Average Remaining Lease Terms and Weighted Average Discount Rates	The following table provides information about our weighted average lease terms and weighted average discount rates as of September 30, 2019: September 30, 2019 Weighted average remaining lease term (years) Operating leases with USD functional currency 8.4 Operating leases with Euro functional currency 4.6 Weighted average discount rate Operating leases with USD functional currency 3.22 % Operating leases with Euro functional currency 1.84 %
Schedule of Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to operating leases is as follows: Nine Months Ended (In thousands) September 30, 2019 Cash paid for amounts included in the measurement of operating lease assets / liabilities Cash used in operating activities related to operating leases $ (775 ) Right-of-use assets obtained in exchange for lease obligations $ 21,418
Components of Net Investment in Sales-Type Leases	As of September 30, 2019 and December 31, 2018, the components of the net investment in sales-type leases were as follows: September 30, December 31, (In thousands) 2019 2018 Current minimum lease payments receivable (1) $ 3,643 $ 11,339 Non-current minimum lease payments receivable (2) 1,073 1,670 Total minimum lease payments receivable 4,716 13,009 Less: Current unearned revenue 445 631 Less: Non-current unearned revenue 210 473 Net investment in sales-type leases $ 4,061 $ 11,905 (1) Included in other receivables on the Condensed Consolidated Balance Sheet. (2) Included in other assets on the Condensed Consolidated Balance Sheet.
Schedule of Components of Sales-type Lease Gross Profit and Interest and Dividend Income Included in Condensed Consolidated Statements of Income	The components of sales-type lease gross profit recognized at the lease commencement date and interest and dividend income, included in the Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2019, were as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2019 September 30, 2019 Sales - Network Solutions $ 47 $ 1,668 Cost of sales - Network Solutions 25 660 Gross profit $ 22 $ 1,008 Interest and dividend income $ 92 $ 278
Schedule of Future Minimum Lease Payments to be Received from Sales-Type Leases	As of September 30, 2019, future minimum lease payments to be received from sales-type leases were as follows: (In thousands) Amount Remainder of 2019 $ 2,700 2020 1,162 2021 542 2022 225 2023 83 Thereafter 4 Total $ 4,716

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax by Component	The following tables present the changes in accumulated other comprehensive income (loss), net of tax, by component for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments ASU 2018-02 Adoption (1) Total As of June 30, 2019 $ (271 ) $ (7,770 ) $ (6,439 ) $ 385 $ (14,095 ) Other comprehensive loss before reclassifications (39 ) — (2,486 ) — (2,525 ) Amounts reclassified from accumulated other comprehensive income (loss) 24 90 — — 114 Net current period other comprehensive income (loss) (15 ) 90 (2,486 ) — (2,411 ) As of September 30, 2019 $ (286 ) $ (7,680 ) $ (8,925 ) $ 385 $ (16,506 ) (1) Three Months Ended September 30, 2018 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments Total As of June 30, 2018 $ (741 ) $ (4,219 ) $ (4,158 ) $ (9,118 ) Other comprehensive income (loss) before reclassifications 1,208 — (451 ) 757 Amounts reclassified from accumulated other comprehensive income (loss) (1,240 ) 37 — (1,203 ) Net current period other comprehensive income (loss) (32 ) 37 (451 ) (446 ) As of September 30, 2018 $ (773 ) $ (4,182 ) $ (4,609 ) $ (9,564 ) The following tables present the changes in accumulated other comprehensive income (loss), net of tax, by component for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30, 2019 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments ASU 2018-02 Adoption (1) Total As of December 31, 2018 $ (563 ) $ (8,041 ) $ (5,812 ) $ — $ (14,416 ) Other comprehensive income (loss) before reclassifications 372 — (3,113 ) — (2,741 ) Amounts reclassified from accumulated other comprehensive income (loss) (95 ) 361 — — 266 Amounts reclassified to retained earnings (1) — — — 385 385 Net current period other comprehensive income (loss) 277 361 (3,113 ) 385 (2,090 ) As of September 30, 2019 $ (286 ) $ (7,680 ) $ (8,925 ) $ 385 $ (16,506 ) (1) Nine Months Ended September 30, 2018 (In thousands) Unrealized Gains (Losses) on Available- for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments Total As of December 31, 2017 $ 2,567 $ (4,286 ) $ (1,576 ) $ (3,295 ) Other comprehensive income (loss) before reclassifications 869 — (3,033 ) (2,164 ) Amounts reclassified from accumulated other comprehensive income (loss) (989 ) 104 — (885 ) Amounts reclassified to retained earnings (1) (3,220 ) — — (3,220 ) Net current period other comprehensive income (loss) (3,340 ) 104 (3,033 ) (6,269 ) As of September 30, 2018 $ (773 ) $ (4,182 ) $ (4,609 ) $ (9,564 ) (1)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	The following tables present the details of reclassifications out of accumulated other comprehensive income (loss) for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized losses on sales of securities $ (32 ) Net investment gain Defined benefit plan adjustments – actuarial losses (130 ) (1) Total reclassifications for the period, before tax (162 ) Tax benefit 48 Total reclassifications for the period, net of tax $ (114 ) (1) Three Months Ended September 30, 2018 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 1,676 Net investment gain Defined benefit plan adjustments – actuarial losses (54 ) (1) Total reclassifications for the period, before tax 1,622 Tax expense (419 ) Total reclassifications for the period, net of tax $ 1,203 (1) The following tables present the details of reclassifications out of accumulated other comprehensive income (loss) for the nine months ended September 30, 2019 and 2018: Nine Months Ended September 30, 2019 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 128 Net investment gain Defined benefit plan adjustments – actuarial losses (523 ) (1) Total reclassifications for the period, before tax (395 ) Tax benefit 129 Total reclassifications for the period, net of tax $ (266 ) (1) Nine Months Ended September 30, 2018 (In thousands) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income Is Presented Unrealized gains (losses) on available-for-sale securities: Net realized gains on sales of securities $ 1,352 Net investment gain Defined benefit plan adjustments – actuarial losses (151 ) (1) Total reclassifications for the period, before tax 1,201 Tax expense (316 ) Total reclassifications for the period, net of tax $ 885 (1)
Other Comprehensive Income (Loss)	The following table presents the tax effects related to the change in each component of other comprehensive income (loss) for the three months ended September 30, 2019 and 2018: Three Months Ended Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Unrealized gain (loss) on available-for-sale securities $ (53 ) $ 14 $ (39 ) $ 1,632 $ (424 ) $ 1,208 Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss) 32 (8 ) 24 (1,676 ) 436 (1,240 ) Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss) 130 (40 ) 90 54 (17 ) 37 Foreign currency translation adjustment (2,486 ) — (2,486 ) (451 ) — (451 ) Total Other Comprehensive Loss $ (2,377 ) $ (34 ) $ (2,411 ) $ (441 ) $ (5 ) $ (446 ) The following table presents the tax effects related to the change in each component of other comprehensive income (loss) for the nine months ended September 30, 2019 and 2018: Nine Months Ended Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Before-Tax Amount Tax (Expense) Benefit Net-of-Tax Amount Unrealized gain (loss) on available-for-sale securities $ 503 $ (131 ) $ 372 $ 1,174 $ (305 ) $ 869 Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss) (128 ) 33 (95 ) (1,352 ) 363 (989 ) Reclassification adjustment for amounts reclassed to retained earnings related to the adoption of ASU 2016-01 — — — (3,220 ) — (3,220 ) Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss) 523 (162 ) 361 151 (47 ) 104 Foreign currency translation adjustment (3,113 ) — (3,113 ) (3,033 ) — (3,033 ) Total Other Comprehensive Income (Loss) $ (2,215 ) $ (260 ) $ (2,475 ) $ (6,280 ) $ 11 $ (6,269 )

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Summary of Calculation of Basic and Diluted Earnings (Loss) Per Share	A summary of the calculation of basic and diluted earnings (loss) per share for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands, except per share amounts) 2019 2018 2019 2018 Numerator Net income (loss) $ (46,123 ) $ 7,589 $ (41,358 ) $ (10,895 ) Denominator Weighted average number of shares – basic 47,824 47,710 47,803 47,927 Effect of dilutive securities Stock options — 27 — — PSUs, RSUs and restricted stock — 97 — — Weighted average number of shares – diluted 47,824 47,834 47,803 47,927 Earnings (loss) per share – basic $ (0.96 ) $ 0.16 $ (0.87 ) $ (0.23 ) Earnings (loss) per share – diluted $ (0.96 ) $ 0.16 $ (0.87 ) $ (0.23 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Sales and Gross Profit of Reportable Segments	The following table presents information about the sales and gross profit of our reportable segments for the three and nine months ended September 30, 2019 and 2018. We do not produce asset information by reportable segment; therefore, it is not reported. Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Sales Gross Profit Sales Gross Profit Network Solutions $ 94,018 $ 37,574 $ 121,043 $ 51,100 Services & Support 20,074 8,757 19,292 7,348 Total $ 114,092 $ 46,331 $ 140,335 $ 58,448 Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Sales Gross Profit Sales Gross Profit Network Solutions $ 359,007 $ 151,654 $ 341,359 $ 133,175 Services & Support 55,267 20,304 47,830 15,002 Total $ 414,274 $ 171,958 $ 389,189 $ 148,177
Disaggregate of Revenue by Reportable Segment and Revenue Category	The following table disaggregates our revenue by reportable segment and revenue category for the three months ended September 30, 2019 and 2018: Three Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 48,902 $ 16,212 $ 65,114 $ 76,046 $ 15,855 $ 91,901 Subscriber Solutions & Experience (1) 40,382 2,094 42,476 37,313 1,239 38,552 Traditional & Other Products 4,734 1,768 6,502 7,684 2,198 9,882 Total $ 94,018 $ 20,074 $ 114,092 $ 121,043 $ 19,292 $ 140,335 (1) The following table disaggregates our revenue by reportable segment and revenue category for the nine months ended September 30, 2019 and 2018 : Nine Months Ended September 30, 2019 September 30, 2018 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Access & Aggregation $ 230,837 $ 43,476 $ 274,313 $ 220,653 $ 37,670 $ 258,323 Subscriber Solutions & Experience (1) 113,545 6,186 119,731 99,396 3,817 103,213 Traditional & Other Products 14,625 5,605 20,230 21,310 6,343 27,653 Total $ 359,007 $ 55,267 $ 414,274 $ 341,359 $ 47,830 $ 389,189 (1) The table below presents sales information by category for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Access & Aggregation $ 65,114 $ 91,901 $ 274,313 $ 258,323 Subscriber Solutions & Experience 42,476 38,552 119,731 103,213 Traditional & Other Products 6,502 9,882 20,230 27,653 Total $ 114,092 $ 140,335 $ 414,274 $ 389,189
Sales Information by Geographic Area	The following table represents sales information by geographic area for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 United States $ 83,144 $ 83,730 $ 230,960 $ 214,039 International 30,948 56,605 183,314 175,150 Total $ 114,092 $ 140,335 $ 414,274 $ 389,189

Liability for Warranty Returns

Liability for Warranty Returns (Tables)	9 Months Ended
	Sep. 30, 2019
Product Warranties Disclosures [Abstract]
Reconciliation of Beginning and Ending Warranty Accrual	A reconciliation of the beginning and ending warranty accrual for the three and nine months ended September 30, 2019 and 2018 is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Balance at beginning of period $ 8,972 $ 10,111 $ 8,623 $ 9,724 Plus: Amounts charged to cost and expenses 816 (34 ) 3,796 6,649 Less: Deductions (1,131 ) (1,053 ) (3,762 ) (7,349 ) Balance at end of period $ 8,657 $ 9,024 $ 8,657 $ 9,024

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2019
Restructuring And Related Activities [Abstract]
Schedule of Reconciliation of Restructuring Liability	A reconciliation of the beginning and ending restructuring liability, which is included in accrued wages and benefits in the Condensed Consolidated Balance Sheets, is as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2019 September 30, 2019 Balance at beginning of period $ 2,655 $ 185 Plus: Amounts charged to cost and expense 1,195 4,658 Less: Amounts paid (252 ) (1,245 ) Balance at end of period $ 3,598 $ 3,598
Schedule of Components of Restructuring Expense	The components of restructuring expense in the Condensed Consolidated Statements of Income are as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Selling, general and administrative expenses $ 531 $ 261 $ 2,078 $ 2,661 Research and development expenses 602 — 1,833 1,814 Cost of sales 62 — 747 2,761 Total restructuring expenses $ 1,195 $ 261 $ 4,658 $ 7,236 The following table represents the components of restructuring expense by geographic area for the three and nine months ended September 30, 2019 and 2018: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2019 2018 2019 2018 Domestic $ 1,116 $ 256 $ 1,941 $ 7,096 International 79 5 2,717 140 Total restructuring expenses $ 1,195 $ 261 $ 4,658 $ 7,236

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 01, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2019	Sep. 30, 2019
Summary Of Significant Accounting Policy [Line Items]
Life insurance proceeds received					$ 1,000
Operating lease, right-of-use asset	$ 10,322				18,529
Operating lease, right-of-use liability	10,322				$ 18,722
ASU 2018-02 [Member]
Summary Of Significant Accounting Policy [Line Items]
Reclassification of tax effects related to adoption ASU	$ 400
Errors in Operating Activity [Member]
Summary Of Significant Accounting Policy [Line Items]
Amount of revision			$ 1,000
Out-of-Period Adjustment [Member]
Summary Of Significant Accounting Policy [Line Items]
Increase (decrease) in cost of goods sold		$ 800		$ (200)
Increase (decrease) in excess and obsolete inventory reserve		$ 800		$ (200)

Business Combinations - Additio

Business Combinations - Additional Information (Detail) - USD ($)	Nov. 30, 2018	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Gain on contingency						$ 1,230,000
Goodwill						$ 7,000,000		$ 7,100,000
Bargain purchase gain net of income taxes							$ 11,322,000
SmartRG Inc [Member]
Business Acquisition [Line Items]
Date of acquisition						Nov. 30, 2018
Business acquisition, description						On November 30, 2018, we acquired SmartRG, Inc. (“SmartRG”), a provider of carrier-class, open connected home platforms and cloud services for broadband service providers in exchange for cash consideration. This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. The revenue from the SmartRG portfolio is included in the Subscriber Solutions & Experience category within the Network Solutions and Services & Support reportable segments.
Business combination, contingent consideration, liability	$ 1,200,000
Gain on contingency			$ 1,200,000
Business combination escrow amount	2,800,000
Goodwill						$ 3,500,000
Acquisition and integration related expenses and amortization of acquired intangibles		$ 500,000		$ 0		$ 1,700,000	$ 0
SmartRG Inc [Member] | Minimum [Member]
Business Acquisition [Line Items]
Business combination potential release of funds	0
SmartRG Inc [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business combination potential release of funds	$ 2,800,000
Sumitomo [Member]
Business Acquisition [Line Items]
Date of acquisition						Mar. 19, 2018
Business acquisition, description						On March 19, 2018, we acquired Sumitomo Electric Lightwave Corp.’s North American EPON business and entered into a technology license and OEM supply agreement with Sumitomo Electric Industries, Ltd.
Bargain purchase gain net of income taxes					$ 11,300,000

Business Combinations - Final A

Business Combinations - Final Allocation of the Purchase Price to the Estimated Fair Value of the Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Nov. 30, 2018	Sep. 30, 2019	Dec. 31, 2018
Assets
Goodwill		$ 6,968	$ 7,106
SmartRG Inc [Member]
Assets
Tangible assets acquired	$ 8,594
Intangible assets	9,960
Goodwill	3,476
Total assets acquired	22,030
Liabilities
Liabilities assumed	(6,001)
Total liabilities assumed	(6,001)
Total purchase price	$ 16,029

Business Combinations - Details

Business Combinations - Details of the Acquired Intangible Assets (Detail) - SmartRG Inc [Member] $ in Thousands	Nov. 30, 2018USD ($)
Business Acquisition [Line Items]
Total, Value	$ 9,960
Developed Technology [Member]
Business Acquisition [Line Items]
Total, Value	$ 7,400
Life (in years)	7 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Total, Value	$ 1,790
Life (in years)	3 years
Licensing Agreements [Member]
Business Acquisition [Line Items]
Total, Value	$ 560
Trade Name [Member]
Business Acquisition [Line Items]
Total, Value	$ 210
Life (in years)	3 years
Licensing Agreements [Member] | Minimum [Member]
Business Acquisition [Line Items]
Life (in years)	5 years
Licensing Agreements [Member] | Maximum [Member]
Business Acquisition [Line Items]
Life (in years)	10 years

Business Combinations - Summary

Business Combinations - Summary of Unaudited Supplemental Pro Forma Information (Detail) - Sumitomo [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Business Acquisition [Line Items]
Pro forma revenue	$ 390,449
Pro forma net loss	$ (23,431)

Revenue - Additional Informatio

Revenue - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)Category
Revenue From Contract With Customer [Abstract]
Number of categories | Category		3
Remaining performance obligations	$ 0	$ 0
Recognized revenue	$ 1,200,000	$ 11,700,000

Revenue - Disaggregate of Reven

Revenue - Disaggregate of Revenue by Reportable Segment and Revenue Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenue	$ 114,092	$ 140,335	$ 414,274	$ 389,189
Access & Aggregation [Member]
Disaggregation Of Revenue [Line Items]
Revenue	65,114	91,901	274,313	258,323
Subscriber Solutions & Experience [Member]
Disaggregation Of Revenue [Line Items]
Revenue	42,476	38,552	119,731	103,213
Traditional & Other Products [Member]
Disaggregation Of Revenue [Line Items]
Revenue	6,502	9,882	20,230	27,653
Network Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	94,018	121,043	359,007	341,359
Network Solutions [Member] | Access & Aggregation [Member]
Disaggregation Of Revenue [Line Items]
Revenue	48,902	76,046	230,837	220,653
Network Solutions [Member] | Subscriber Solutions & Experience [Member]
Disaggregation Of Revenue [Line Items]
Revenue	40,382	37,313	113,545	99,396
Network Solutions [Member] | Traditional & Other Products [Member]
Disaggregation Of Revenue [Line Items]
Revenue	4,734	7,684	14,625	21,310
Services & Support [Member]
Disaggregation Of Revenue [Line Items]
Revenue	20,074	19,292	55,267	47,830
Services & Support [Member] | Access & Aggregation [Member]
Disaggregation Of Revenue [Line Items]
Revenue	16,212	15,855	43,476	37,670
Services & Support [Member] | Subscriber Solutions & Experience [Member]
Disaggregation Of Revenue [Line Items]
Revenue	2,094	1,239	6,186	3,817
Services & Support [Member] | Traditional & Other Products [Member]
Disaggregation Of Revenue [Line Items]
Revenue	$ 1,768	$ 2,198	$ 5,605	$ 6,343

Revenue - Information about Rec

Revenue - Information about Receivables, Contract Assets, and Unearned Revenue from Contracts with Customers (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Accounts receivable, net	$ 90,647	$ 99,385
Contract assets	2,434	3,766
Unearned revenue	14,022	17,940
Non-current unearned revenue	$ 4,581	$ 5,296

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Line Items]
Effective tax rate expense (benefit)		197.10%	34.90%
Effective tax rate reduction related to transfer pricing study		9.38%
Deferred tax assets, gross	$ 49,405	$ 49,405
Valuation allowance established against deferred tax assets	42,913	42,913
Deferred tax assets, state research and development credits	5,800	5,800
Deferred tax assets	6,492	6,492
Domestic [Member]
Income Tax Disclosure [Line Items]
Valuation allowance established against deferred tax assets	37,100
Deferred tax assets, gross	40,496	40,496
Valuation allowance established against deferred tax assets	$ 40,496	$ 40,496

Income Taxes - Summary of Suppl

Income Taxes - Summary of Supplemental Balance Sheet Information Related to Deferred Tax Assets (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	$ 49,405
Valuation Allowance	(42,913)
Deferred Tax Assets, net	6,492
Domestic [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	40,496
Valuation Allowance	(40,496)
International [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	8,909
Valuation Allowance	(2,417)
Deferred Tax Assets, net	$ 6,492

Pension Benefit Plan - Summariz

Pension Benefit Plan - Summarization of Components of Net Periodic Pension Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Service cost	$ 366	$ 294	$ 1,109	$ 905
Interest cost	158	179	479	551
Expected return on plan assets	(346)	(381)	(1,049)	(1,174)
Amortization of actuarial losses	198	61	600	188
Net periodic pension cost	$ 376	$ 153	$ 1,139	$ 470

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense Related to Stock Options, Performance Stock Units (PSUs), Restricted Stock Units (RSUs) and Restricted Stock (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,871	$ 1,640	$ 5,184	$ 5,243
Tax benefit for expense associated with stock options, PSUs, RSUs and restricted stock	(446)	(292)	(1,235)	(1,016)
Total stock-based compensation expense, net of tax	1,425	1,348	3,949	4,227
Stock-based Compensation Expense Included in Cost of Sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	83	101	272	298
Selling, General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	1,142	894	2,867	2,924
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	646	645	2,045	2,021
Stock-based Compensation Expense Included in Operating Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,788	$ 1,539	$ 4,912	$ 4,945

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Options Outstanding (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Stock Options, Stock options outstanding, Beginning Balance	4,382
Number of Stock Options, Stock options exercised	(34)
Number of Stock Options, Stock options forfeited	(28)
Number of Stock Options, Stock options expired	(183)
Number of Stock Options, Stock options outstanding, Ending Balance	4,137	4,382
Number of Stock Options, Stock options exercisable	3,915
Weighted Avg. Exercise Price, Stock options outstanding, Beginning Balance	$ 22.91
Weighted Avg. Exercise Price, Stock options exercised	15.53
Weighted Avg. Exercise Price, Stock options forfeited	15.53
Weighted Avg. Exercise Price, Stock options expired	24.41
Weighted Avg. Exercise Price, Stock options outstanding, Ending Balance	22.96	$ 22.91
Weighted Avg. Exercise Price, Stock options exercisable	$ 23.39
Weighted Avg. Remaining Contractual Life In Years, Stock options outstanding	3 years 3 months 7 days	4 years 1 month 6 days
Weighted Avg. Remaining Contractual Life In Years, Stock options exercisable	3 years 1 month 9 days
Aggregate Intrinsic Value, Stock options outstanding	$ 0

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Options) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value based on fair market value	$ 0		$ 0
Total pre-tax intrinsic value of options exercised			$ 100
Number of Stock options, granted	0	0	0	0
Unvested Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 100		$ 100
Recognition period of unvested compensation expense			3 months 18 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of PSUs, RSUs and Restricted Stock Outstanding (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Unvested PSUs, RSUs and restricted stock outstanding, beginning balance | shares	1,570
Number of Shares, PSUs, RSUs and restricted stock granted | shares	63
Number of Shares, PSUs, RSUs and restricted stock vested | shares	(22)
Number of Shares, PSUs, RSUs and restricted stock forfeited | shares	(175)
Number of Shares, Unvested PSUs, RSUs and restricted stock outstanding, ending balance | shares	1,436
Weighted Avg. Grant Date Fair Value, Unvested PSUs, RSUs and restricted stock outstanding, Beginning Balance | $ / shares	$ 18.52
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock granted | $ / shares	12.81
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock vested | $ / shares	17.13
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock forfeited | $ / shares	18.69
Weighted Avg. Grant Date Fair Value, Unvested PSUs, RSUs and restricted stock outstanding, Ending Balance | $ / shares	$ 18.27

Stock-Based Compensation (PSUs,

Stock-Based Compensation (PSUs, RSUs and Restricted Stock) - Additional Information (Detail) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,871,000	$ 1,640,000	$ 5,184,000	$ 5,243,000
Market-Based PSUs, RSUs and Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options	11,600,000		$ 11,600,000
Recognition period of unvested compensation expense			2 years 4 months 24 days
Performance-Based PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options	8,200,000		$ 8,200,000
Recognition period of unvested compensation expense			3 months 18 days
Stock-based compensation expense	$ 0	$ 0	$ 0	$ 0
Stock Options, PSUs, RSUs or Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options available for issuance under shareholders-approved equity plan	2.7		2.7

Investments - Debt Securities a

Investments - Debt Securities and Other Investments, Recorded at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 35,784	$ 41,042
Gross Unrealized Gains	163	27
Gross Unrealized Losses	(34)	(270)
Fair Value	35,913	40,799
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,733	20,777
Gross Unrealized Gains	95	19
Gross Unrealized Losses		(112)
Fair Value	10,828	20,684
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	931	1,339
Gross Unrealized Losses	(1)	(26)
Fair Value	930	1,313
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,222	5,230
Gross Unrealized Gains	35	5
Gross Unrealized Losses	(2)	(14)
Fair Value	7,255	5,221
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,366	3,833
Gross Unrealized Gains	29	2
Gross Unrealized Losses	(7)	(44)
Fair Value	7,388	3,791
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,160	9,271
Gross Unrealized Gains	4	1
Gross Unrealized Losses	(21)	(66)
Fair Value	9,143	9,206
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	372	592
Gross Unrealized Losses	(3)	(8)
Fair Value	$ 369	$ 584

Investments - Contractual Matur

Investments - Contractual Maturities of Debt Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Fair Value/Carrying Value	$ 35,913	$ 40,799
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	3,154
One to two years	4,316
Two to three years	3,068
Three to five years	290
Available-for-sale debt securities, Fair Value/Carrying Value	10,828	20,684
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	930
Available-for-sale debt securities, Fair Value/Carrying Value	930	1,313
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	941
Two to three years	2,475
Three to five years	1,593
Five to ten years	1,666
More than ten years	580
Available-for-sale debt securities, Fair Value/Carrying Value	7,255	5,221
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	215
Two to three years	1,072
Three to five years	920
Five to ten years	680
More than ten years	4,501
Available-for-sale debt securities, Fair Value/Carrying Value	7,388	3,791
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Two to three years	7,528
Three to five years	1,615
Available-for-sale debt securities, Fair Value/Carrying Value	9,143	9,206
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Three to five years	369
Available-for-sale debt securities, Fair Value/Carrying Value	$ 369	$ 584

Investments - Gross Realized Ga

Investments - Gross Realized Gains and Losses on Sale of Debt Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Gross realized gains on debt securities	$ 36	$ 24	$ 85	$ 49
Gross realized losses on debt securities	(7)	(50)	(40)	(365)
Total gain (loss) recognized, net	$ 29	$ (26)	$ 45	$ (316)

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Jan. 01, 2018
Schedule of Investments [Line Items]
Restricted certificate of deposit held		$ 25.6
Restricted certificate of deposit held, maturity date		Jan. 8, 2020
Transfer to investments	$ 3.4
Carrying value		$ 3.4
Other Receivables [Member]
Schedule of Investments [Line Items]
Note receivable		$ 0.9	$ 4.3
ASU 2016-01 [Member]
Schedule of Investments [Line Items]
Reclassification of net unrealized gains of marketable equity securities from AOCI to retained earnings				$ 3.2
Alabama State Industrial Development Authority [Member]
Schedule of Investments [Line Items]
Maturity date of bond		Jan. 1, 2020
Percentage of interest on bond		2.00%
Alabama State Industrial Development Authority [Member] | Taxable Revenue Bond [Member]
Schedule of Investments [Line Items]
Collateral deposit against outstanding principal amount		$ 25.6	25.6
Alabama State Industrial Development Authority [Member] | Taxable Revenue Bond [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Investments [Line Items]
Estimated fair value of bond		$ 25.6	$ 25.4
Investment [Member] | Issuer Concentration [Member] | Market Value of Total Investment Portfolio [Member]
Schedule of Investments [Line Items]
Investment concentration risk percentage		5.00%

Investments - Realized and Unre

Investments - Realized and Unrealized Gains and Losses for Marketable Equity Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Realized gains (losses) on equity securities sold	$ (20)	$ 1,240	$ (83)	$ 1,587
Unrealized gains (losses) on equity securities held	(225)	3,293	8,233	4,129
Total gain (loss) recognized, net	$ (245)	$ 4,533	$ 8,150	$ 5,716

Investments - Fair Value Measur

Investments - Fair Value Measurements of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	$ 35,913	$ 40,799
Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	3,112	1,554
Total debt and equity securities at fair value	89,201	86,071
Total	92,313	87,625
Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,817	1,554
Total debt and equity securities at fair value	62,431	54,478
Total	64,248	56,032
Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,295
Total debt and equity securities at fair value	26,770	31,593
Total	28,065	31,593
Money Market Funds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,817	1,554
Money Market Funds [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,817	1,554
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	10,828	20,684
Corporate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	10,828	20,684
Corporate Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	10,828	20,684
Commercial Paper | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,295
Commercial Paper | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1,295
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	930	1,313
Municipal Fixed-Rate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	930	1,313
Municipal Fixed-Rate Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	930	1,313
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,255	5,221
Asset-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,255	5,221
Asset-Backed Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,255	5,221
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,388	3,791
Mortgage/Agency-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,388	3,791
Mortgage/Agency-Backed Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	7,388	3,791
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	9,143	9,206
U.S. Government Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	9,143	9,206
U.S. Government Bonds [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	9,143	9,206
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	369	584
Foreign Government Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	369	584
Foreign Government Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	369	584
Marketable Equity Securities - Various Industries [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	32,543	26,763
Marketable Equity Securities - Various Industries [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	32,543	26,763
Deferred Compensation Plan Assets [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	20,580	18,256
Deferred Compensation Plan Assets [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	20,580	18,256
Equity in Escrow [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	165	253
Equity in Escrow [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	$ 165	$ 253

Inventory - Components of Inven

Inventory - Components of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 39,133	$ 45,333
Work in process	1,083	1,638
Finished goods	64,725	52,877
Total	$ 104,941	$ 99,848

Inventory - Additional Informat

Inventory - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventory valuation reserves	$ 32	$ 30

Property, Plant and Equipment -

Property, Plant and Equipment - Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Land	$ 4,575	$ 4,575
Building and land improvements	34,634	34,379
Building	68,247	68,183
Furniture and fixtures	19,878	19,831
Computer hardware and software	72,390	92,071
Engineering and other equipment	129,479	127,060
Total Property, Plant and Equipment	329,203	346,099
Less accumulated depreciation	(255,819)	(265,464)
Total Property, Plant and Equipment, net	$ 73,384	$ 80,635

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Depreciation	$ 3,100	$ 3,100	$ 9,300	$ 9,500
Asset impairments	$ 3,872		$ 3,872

Goodwill - Additional Informati

Goodwill - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill, relates to acquisition		$ 7	$ 7.1
SmartRG Inc [Member]
Goodwill [Line Items]
Goodwill, relates to acquisition		3.5
Goodwill, reduced amount relates to acquisition		0.1
Network Solutions [Member]
Goodwill [Line Items]
Goodwill, relates to acquisition	$ 6.6	6.6	6.7
Services & Support [Member]
Goodwill [Line Items]
Goodwill, relates to acquisition	$ 0.4	$ 0.4	$ 0.4

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Value	$ 42,475	$ 45,326
Accumulated Amortization	(13,362)	(12,143)
Net Value	29,113	33,183
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	22,235	22,455
Accumulated Amortization	(6,671)	(5,380)
Net Value	15,564	17,075
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	10,170	12,801
Accumulated Amortization	(3,094)	(4,867)
Net Value	7,076	7,934
Licensed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	5,900	5,900
Accumulated Amortization	(1,011)	(520)
Net Value	4,889	5,380
Supplier Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	2,800	2,800
Accumulated Amortization	(2,158)	(1,108)
Net Value	642	1,692
Licensing Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	560	560
Accumulated Amortization	(61)	(5)
Net Value	499	555
Patent [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	500	500
Accumulated Amortization	(209)	(157)
Net Value	291	343
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Value	310	310
Accumulated Amortization	(158)	(106)
Net Value	$ 152	$ 204

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Intangible Assets Net Excluding Goodwill [Abstract]
Amortization expense	$ 1.3	$ 0.9	$ 4	$ 2.4

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
Remainder of 2019	$ 1,329
2020	4,436
2021	4,088
2022	3,464
2023	3,313
Thereafter	12,483
Net Value	$ 29,113	$ 33,183

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Lessor and Lessee Lease Description [Line Items]
Operating lease, option to extend, existence		true
Operating lease, option to terminate, existence		true
Short-term lease cost	$ 100,000	$ 300,000
Variable lease cost	300,000	700,000
Future operating lease payments	20,812,000	20,812,000	$ 7,600,000
Allowance for credit losses for our investment in sales type leases	$ 0	$ 0	$ 0
Minimum [Member]
Lessor and Lessee Lease Description [Line Items]
Operating lease, remaining lease terms		2 months
Operating lease, options to terminate term		3 months
Maximum [Member]
Lessor and Lessee Lease Description [Line Items]
Operating lease, remaining lease terms		6 years
Operating lease, renewal term	5 years	5 years
Lessor sales type lease arrangement terms for network equipments		5 years

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Balance Sheet Information Related to Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
ASSETS
Operating lease asset	$ 18,529	$ 10,322
Operating lease, right-of-use asset, statement of financial position [extensible list]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Liabilities
Current operating lease liability	$ 3,063	$ 2,948
Operating lease, liability, current, statement of financial position [extensible list]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Non-current operating lease liability	$ 15,659	$ 7,374
Operating lease, liability, noncurrent, statement of financial position [extensible list]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Total lease liability	$ 18,722	$ 10,322

Leases - Components of Lease Ex

Leases - Components of Lease Expense included in Condensed Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lessor Lease Description [Line Items]
Total operating lease expense	$ 1,215	$ 2,830
Selling, General and Administrative Expenses [Member]
Lessor Lease Description [Line Items]
Total operating lease expense	352	1,050
Research and Development Expenses [Member]
Lessor Lease Description [Line Items]
Total operating lease expense	847	1,731
Stock-based Compensation Expense Included in Cost of Sales [Member]
Lessor Lease Description [Line Items]
Total operating lease expense	$ 16	$ 49

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Lease Liabilities Payments Due [Abstract]
Remainder of 2019	$ 1,044
2020	3,417
2021	3,071
2022	2,672
2023	2,350
Thereafter	8,258
Total lease payments	20,812		$ 7,600
Less: Interest	(2,090)
Operating lease, right-of-use liability	$ 18,722	$ 10,322

Leases - Future Minimum Rental

Leases - Future Minimum Rental Payments under Non-Cancelable Operating Leases, Including Renewals Determined to be Reasonably Assured, with Original Maturities of Greater than 12 Months (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2019	$ 3,873
2020	3,580
2021	2,771
2022	2,053
2023	1,317
Thereafter	762
Total	$ 14,356

Leases - Schedule of Weighted A

Leases - Schedule of Weighted Average Remaining Lease Terms and Weighted Average Discount Rates (Detail)	Sep. 30, 2019
USD
Weighted average remaining lease term (years)
Operating leases with functional currency	8 years 4 months 24 days
Weighted average discount rate
Operating leases with functional currency	3.22%
Euro
Weighted average remaining lease term (years)
Operating leases with functional currency	4 years 7 months 6 days
Weighted average discount rate
Operating leases with functional currency	1.84%

Leases - Schedule of Suppleme_2

Leases - Schedule of Supplemental Cash Flow Information Related to Operating Leases (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Cash paid for amounts included in the measurement of operating lease assets / liabilities
Cash used in operating activities related to operating leases	$ (775)
Right-of-use assets obtained in exchange for lease obligations	$ 21,418

Leases - Components of Net Inve

Leases - Components of Net Investment in Sales-Type Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Sales Type Leases Net Investment In Leases [Abstract]
Current minimum lease payments receivable	$ 3,643	$ 11,339
Non-current minimum lease payments receivable	1,073	1,670
Total minimum lease payments receivable	4,716	13,009
Less: Current unearned revenue	445	631
Less: Non-current unearned revenue	210	473
Net investment in sales-type leases	$ 4,061	$ 11,905

Leases - Schedule of Components

Leases - Schedule of Components of Sales-type Lease Gross Profit and Interest and Dividend Income Included in Condensed Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Sales [Member] | Network Solutions [Member]
Lessor Lease Description [Line Items]
Sales type leases	$ 47	$ 1,668
Stock-based Compensation Expense Included in Cost of Sales [Member] | Network Solutions [Member]
Lessor Lease Description [Line Items]
Sales type leases	25	660
Gross Profit [Member]
Lessor Lease Description [Line Items]
Sales type leases	22	1,008
Interest and Dividend Income [Member]
Lessor Lease Description [Line Items]
Sales type leases	$ 92	$ 278

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments to be Received from Sales-Type Leases (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Sales Type And Direct Financing Leases Lease Receivable Fiscal Year Maturity [Abstract]
Remainder of 2019	$ 2,700
2020	1,162
2021	542
2022	225
2023	83
Thereafter	4
Total	$ 4,716

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Equity [Abstract]
Stock repurchased, shares	13,000,000
Shares repurchased, average price per share | $ / shares	$ 14.06
Additional shares authorized for purchase	2,500,000
Maximum shares authorized for repurchase, prior and new announcements and total after new announcement	5,000,000

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 445,975	$ 459,627	$ 446,279	$ 497,911
Other comprehensive income (loss) before reclassifications	(2,525)	757	(2,741)	(2,164)
Amounts reclassified from accumulated other comprehensive income (loss)	114	(1,203)	266	(885)
Amounts reclassified to retained earnings			385	(3,220)
Net current period other comprehensive income (loss)	(2,411)	(446)	(2,090)	(6,269)
Ending Balance	394,955	463,601	394,955	463,601
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	385
Amounts reclassified to retained earnings			385
Net current period other comprehensive income (loss)			385
Ending Balance	385		385
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(271)	(741)	(563)	2,567
Other comprehensive income (loss) before reclassifications	(39)	1,208	372	869
Amounts reclassified from accumulated other comprehensive income (loss)	24	(1,240)	(95)	(989)
Amounts reclassified to retained earnings				(3,220)
Net current period other comprehensive income (loss)	(15)	(32)	277	(3,340)
Ending Balance	(286)	(773)	(286)	(773)
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(7,770)	(4,219)	(8,041)	(4,286)
Amounts reclassified from accumulated other comprehensive income (loss)	90	37	361	104
Net current period other comprehensive income (loss)	90	37	361	104
Ending Balance	(7,680)	(4,182)	(7,680)	(4,182)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(6,439)	(4,158)	(5,812)	(1,576)
Other comprehensive income (loss) before reclassifications	(2,486)	(451)	(3,113)	(3,033)
Net current period other comprehensive income (loss)	(2,486)	(451)	(3,113)	(3,033)
Ending Balance	(8,925)	(4,609)	(8,925)	(4,609)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(14,095)	(9,118)	(14,416)	(3,295)
Ending Balance	$ (16,506)	$ (9,564)	$ (16,506)	$ (9,564)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	$ (67,761)			$ (81,887)			$ (242,316)	$ (241,012)
Income (Loss) Before Income Taxes	(18,406)			3,220			(13,921)	(22,784)
Tax benefit (expense)	(27,717)			4,369			(27,437)	11,889
Net Income (Loss)	(46,123)	$ 3,995	$ 770	7,589	$ (7,670)	$ (10,814)	(41,358)	(10,895)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit plan adjustments – actuarial losses	(130)			(54)			(523)	(151)
Income (Loss) Before Income Taxes	(162)			1,622			(395)	1,201
Tax benefit (expense)	48			(419)			129	(316)
Net Income (Loss)	(114)			1,203			(266)	885
Unrealized Gains (Losses) on Available-for-Sale Securities [Member] | Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net investment gain	$ (32)			$ 1,676			$ 128	$ 1,352

Stockholders' Equity - Tax Effe

Stockholders' Equity - Tax Effects Related to the Change in Each Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity [Abstract]
Unrealized gain (loss) on available-for-sale securities, Before-Tax Amount	$ (53)			$ 1,632			$ 503	$ 1,174
Unrealized gain (loss) on available-for-sale securities, Tax (Expense) Benefit	14			(424)			(131)	(305)
Unrealized gain (loss) on available-for-sale securities, Net-of-Tax Amount	(39)			1,208			372	869
Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss), Before-Tax Amount	32			(1,676)			(128)	(1,352)
Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss), Tax (Expense) Benefit	(8)			436			33	363
Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss), Net-of-Tax Amount	24			(1,240)			(95)	(989)
Reclassification adjustment for amounts reclassed to retained earnings related of the adoption of ASU 2016-01, Before-Tax Amount								(3,220)
Reclassification adjustment for amounts reclassed to retained earnings related of the adoption of ASU 2016-01, Net-of-Tax Amount								(3,220)
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss), Before-Tax Amount	130			54			523	151
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss), Tax (Expense) Benefit	(40)			(17)			(162)	(47)
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss), Net-of-Tax Amount	90			37			361	104
Foreign currency translation adjustment, Before-Tax Amount	(2,486)			(451)			(3,113)	(3,033)
Foreign currency translation adjustment, Net-of-Tax Amount	(2,486)			(451)			(3,113)	(3,033)
Total Other Comprehensive Income (Loss), Before-Tax Amount	(2,377)			(441)			(2,215)	(6,280)
Total Other Comprehensive Income (Loss), Tax (Expense) Benefit	(34)			(5)			(260)	11
Other Comprehensive Loss, net of tax	$ (2,411)	$ 790	$ (854)	$ (446)	$ (3,315)	$ (2,508)	$ (2,475)	$ (6,269)

Earnings (Loss) Per Share - Sum

Earnings (Loss) Per Share - Summary of Calculation of Basic and Diluted Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net Income (Loss)	$ (46,123)	$ 3,995	$ 770	$ 7,589	$ (7,670)	$ (10,814)	$ (41,358)	$ (10,895)
Denominator
Weighted average number of shares – basic	47,824			47,710			47,803	47,927
Effect of dilutive securities
Stock options				27
PSUs, RSUs and restricted stock				97
Weighted average number of shares – diluted	47,824			47,834			47,803	47,927
Earnings (loss) per share – basic	$ (0.96)			$ 0.16			$ (0.87)	$ (0.23)
Earnings (loss) per share – diluted	$ (0.96)			$ 0.16			$ (0.87)	$ (0.23)

Earnings (Loss) Per Share - Add

Earnings (Loss) Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share		1.8
Unvested Stock Options, PSUs, RSUs and Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share	4.1		3	2.3

Segment Information - Additiona

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019CategorySegment
Segment Reporting [Abstract]
Number of reportable segments | Segment	2
Number of categories | Category	3

Segment Information - Sales and

Segment Information - Sales and Gross Profit of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Sales	$ 114,092	$ 140,335	$ 414,274	$ 389,189
Gross Profit	46,331	58,448	171,958	148,177
Network Solutions [Member]
Segment Reporting Information [Line Items]
Sales	94,018	121,043	359,007	341,359
Gross Profit	37,574	51,100	151,654	133,175
Services & Support [Member]
Segment Reporting Information [Line Items]
Sales	20,074	19,292	55,267	47,830
Gross Profit	$ 8,757	$ 7,348	$ 20,304	$ 15,002

Segment Information - Sales Inf

Segment Information - Sales Information by Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenue	$ 114,092	$ 140,335	$ 414,274	$ 389,189
Access & Aggregation [Member]
Disaggregation Of Revenue [Line Items]
Revenue	65,114	91,901	274,313	258,323
Subscriber Solutions & Experience [Member]
Disaggregation Of Revenue [Line Items]
Revenue	42,476	38,552	119,731	103,213
Traditional & Other Products [Member]
Disaggregation Of Revenue [Line Items]
Revenue	$ 6,502	$ 9,882	$ 20,230	$ 27,653

Segment Information- Sales Info

Segment Information- Sales Information by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from External Customer [Line Items]
Sales	$ 114,092	$ 140,335	$ 414,274	$ 389,189
United States [Member]
Revenue from External Customer [Line Items]
Sales	83,144	83,730	230,960	214,039
International [Member]
Revenue from External Customer [Line Items]
Sales	$ 30,948	$ 56,605	$ 183,314	$ 175,150

Liability for Warranty Return_2

Liability for Warranty Returns - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Product Warranties Disclosures [Abstract]
Period of assurance-based warranty for product defects	90 days to five years
Liability for warranty obligations	$ 8,657	$ 8,972	$ 8,623	$ 9,024	$ 10,111	$ 9,724

Liability for Warranty Return_3

Liability for Warranty Returns - Summary of Warranty Expense and Write-Off Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Product Warranties Disclosures [Abstract]
Balance at beginning of period	$ 8,972	$ 10,111	$ 8,623	$ 9,724
Plus: Amounts charged to cost and expenses	816	(34)	3,796	6,649
Less: Deductions	(1,131)	(1,053)	(3,762)	(7,349)
Balance at end of period	$ 8,657	$ 9,024	$ 8,657	$ 9,024

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Oct. 17, 2019Officer	Sep. 30, 2019USD ($)EquityFund
Contingencies And Commitments [Line Items]
Number of private equity funds | EquityFund		2
Commitments towards private equity funds | $		$ 7.7
Investment Commitments [Member]
Contingencies And Commitments [Line Items]
Aggregate investment committed in private equity funds | $		$ 7.9
Current Executive Officers [Member] | Subsequent Event [Member]
Contingencies And Commitments [Line Items]
Number of officers | Officer	2
Former Executive Officers [Member] | Subsequent Event [Member]
Contingencies And Commitments [Line Items]
Number of officers | Officer	1

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Cumulative amount incurred for restructuring program	$ 1.1	$ 0.3	$ 1.9	$ 7.2	$ 7.3

Restructuring - Schedule of Rec

Restructuring - Schedule of Reconciliation of Restructuring Liability (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring And Related Activities [Abstract]
Balance at beginning of period	$ 2,655		$ 185
Plus: Amounts charged to cost and expense	1,195	$ 261	4,658	$ 7,236
Less: Amounts paid	(252)		(1,245)
Balance at end of period	$ 3,598		$ 3,598

Restructuring - Schedule of Com

Restructuring - Schedule of Components of Restructuring Expense in Condensed Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 1,195	$ 261	$ 4,658	$ 7,236
Selling, General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	531	$ 261	2,078	2,661
Research and Development Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	602		1,833	1,814
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 62		$ 747	$ 2,761

Restructuring - Schedule of C_2

Restructuring - Schedule of Components of Restructuring Expense by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 1,195	$ 261	$ 4,658	$ 7,236
United States [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	1,116	256	1,941	7,096
International [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 79	$ 5	$ 2,717	$ 140

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Oct. 30, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 02, 2019
Subsequent Event [Line Items]
Dividend payments		$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividend declaration date	Oct. 30, 2019
Dividend payments	$ 0.09
Dividend record date	Nov. 14, 2019
Dividend payment date	Dec. 2, 2019
Scenario Forecast [Member]
Subsequent Event [Line Items]
Quarterly dividend payable, aggregate amount subsequent to balance sheet date								$ 4.3