Cogent Communications (CCOI) 10-K 28 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
Entity File Number	000-51829
Entity Registrant Name	COGENT COMMUNICATIONS HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5706863
Entity Address, Address Line One	2450 N Street N.W.
Entity Address, Country	US
Entity Address, City or Town	Washington, D.C
Entity Address, Postal Zip Code	20037
City Area Code	(202)
Local Phone Number	295-4200
Title of 12(b) Security	Common Stock
Trading Symbol	CCOI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		46,850,718
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001158324
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2.5

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 399,422	$ 276,093
Accounts receivable, net of allowance for doubtful accounts of $1,771 and $1,263, respectively	40,484	41,709
Prepaid expenses and other current assets	35,822	32,535
Total current assets	475,728	350,337
Property and equipment	1,366,782	1,300,503
Accumulated depreciation and amortization	(997,853)	(925,178)
Total property and equipment, net	368,929	375,325
Right-of-use leased assets	73,460
Deferred tax assets	335	2,733
Deposits and other assets	13,672	11,455
Total assets	932,124	739,850
Current liabilities:
Accounts payable	11,075	8,519
Accrued and other current liabilities	51,301	51,431
Current maturities, operating lease liabilities	10,101
Installment payment agreement, current portion, net of discount of $350 and $395, respectively	9,063	8,283
Current maturities, finance lease obligations	8,154	7,074
Total current liabilities	89,694	75,307
Operating lease liabilities, net of current maturities	86,690
Finance lease obligations, net of current maturities	161,635	156,706
Other long term liabilities	15,327	25,380
Total liabilities	1,135,803	888,852
Commitments and contingencies:
Stockholders' equity:
Common stock, $0.001 par value; 75,000,000 shares authorized; 46,821,586 and 46,336,499 shares issued and outstanding, respectively	47	46
Additional paid-in capital	493,178	471,331
Accumulated other comprehensive income	(12,326)	(10,928)
Accumulated deficit	(684,578)	(609,451)
Total stockholders' deficit	(203,679)	(149,002)
Total liabilities and stockholders' equity	932,124	739,850
Senior unsecured 2024 notes
Current liabilities:
Senior unsecured notes	150,001
Senior secured 2022 notes
Current liabilities:
Senior secured notes	444,088	443,710
Senior unsecured 2021 notes
Current liabilities:
Senior unsecured notes	$ 188,368	$ 187,749

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,771	$ 1,263
Liabilities and stockholders' equity
Installment payment agreement, current portion, net of discount	$ 350	$ 395
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	46,840,434	46,336,499
Common stock, shares outstanding	46,840,434	46,336,499
Senior secured 2022 notes
Liabilities and stockholders' equity
Unamortized debt costs	$ 1,897	$ 2,695
Unamortized debt premium	985	1,405
Senior unsecured 2024 notes
Liabilities and stockholders' equity
Unamortized debt costs	1,410
Senior unsecured 2021 notes
Liabilities and stockholders' equity
Unamortized debt costs	$ 857	$ 1,476

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Service revenue	$ 546,159	$ 520,193	$ 485,175
Operating expenses:
Network operations (including $944, $895 and $604 of equity-based compensation expense, respectively), exclusive of amounts shown separately	219,801	219,526	209,278
Selling, general, and administrative (including $17,466, $16,813 and $12,686 of equity-based compensation expense, respectively)	146,913	133,858	127,915
Depreciation and amortization	80,247	81,233	75,926
Total operating expenses	446,961	434,617	413,119
Gains on equipment transactions	1,059	982	3,862
Operating income	100,257	86,558	75,918
Interest income and other	9,870	5,880	3,667
Interest expense	(57,453)	(51,056)	(48,467)
Income before income taxes	52,674	41,382	31,118
Income tax expense	(15,154)	(12,715)	(25,242)
Net income	37,520	28,667	5,876
Comprehensive income:
Net income	37,520	28,667	5,876
Foreign currency translation adjustment	(1,398)	(6,328)	12,593
Comprehensive income	$ 36,122	$ 22,339	$ 18,469
Net income per common share:
Basic net income per common share (in dollars per share)	$ 0.82	$ 0.63	$ 0.13
Diluted net income per common share (in dollars per share)	0.81	0.63	0.13
Dividends declared per common share (in dollars per share)	$ 2.44	$ 2.12	$ 1.80
Weighted-average common shares - basic (in shares)	45,542,315	45,280,161	44,855,263
Weighted-average common shares - diluted (in shares)	46,080,395	45,780,954	45,184,203

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity-based compensation expense	$ 18,460	$ 17,708	$ 13,290
Network operations
Equity-based compensation expense	994	895	604
Selling, general and administrative
Equity-based compensation expense	$ 17,466	$ 16,813	$ 12,686

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2016	$ 45	$ 442,799	$ (17,193)	$ (478,905)	$ (53,254)
Balance (in shares) at Dec. 31, 2016	45,478,787
Increase (Decrease) in Stockholders' Equity
Forfeitures of shares granted to employees (in shares)	(10,181)
Equity-based compensation		14,504			14,504
Foreign currency translation			12,593		12,593
Issuances of common stock	$ 1				1
Issuances of common stock (in shares)	499,654
Exercises of options		1,222			1,222
Exercised (in shares)	39,289
Common stock purchases and retirement		(1,829)			(1,829)
Common stock purchases and retirement (in shares)	(46,750)
Dividends paid				(81,657)	(81,657)
Net income				5,876	5,876
Balance at Dec. 31, 2017	$ 46	456,696	(4,600)	(554,686)	(102,544)
Balance (in shares) at Dec. 31, 2017	45,960,799
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment from adoption of ASC 606				14,455	14,455
Forfeitures of shares granted to employees (in shares)	(24,973)
Equity-based compensation		19,431			19,431
Foreign currency translation			(6,328)		(6,328)
Issuances of common stock (in shares)	496,228
Exercises of options		1,768			1,768
Exercised (in shares)	52,440
Common stock purchases and retirement		(6,564)			(6,564)
Common stock purchases and retirement (in shares)	(147,995)
Dividends paid				(97,887)	(97,887)
Net income				28,667	28,667
Balance at Dec. 31, 2018	$ 46	471,331	(10,928)	(609,451)	$ (149,002)
Balance (in shares) at Dec. 31, 2018	46,336,499				46,336,499
Increase (Decrease) in Stockholders' Equity
Forfeitures of shares granted to employees (in shares)	(12,632)
Equity-based compensation		20,210			$ 20,211
Foreign currency translation			(1,398)		(1,398)
Issuances of common stock	$ 1				1
Issuances of common stock (in shares)	473,550
Exercises of options		1,637			1,636
Exercised (in shares)	43,017
Dividends paid				(112,647)	(112,647)
Net income				37,520	37,520
Balance at Dec. 31, 2019	$ 47	$ 493,178	$ (12,326)	$ (684,578)	$ (203,679)
Balance (in shares) at Dec. 31, 2019	46,840,434				46,840,434

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 37,520	$ 28,667	$ 5,876
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	80,247	81,233	75,926
Amortization of debt discount and premium	1,807	1,533	1,239
Equity-based compensation expense (net of amounts capitalized)	18,460	17,708	13,290
Unrealized foreign currency exchange gain on 2024 Euro notes	(2,273)
Gains - equipment transactions and other, net	(358)	(1,109)	(4,833)
Deferred income taxes	12,158	11,117	24,679
Changes in operating assets and liabilities:
Accounts receivable	1,067	(3,204)	(4,161)
Prepaid expenses and other current assets	(3,730)	(438)	1,146
Deposits and other assets	(1,131)	(1,490)	1,111
Accounts payable, accrued liabilities and other long-term liabilities	5,042	(96)	(2,571)
Net cash provided by operating activities	148,809	133,921	111,702
Cash flows from investing activities:
Purchases of property and equipment	(46,958)	(49,937)	(45,801)
Net cash used in investing activities	(46,958)	(49,937)	(45,801)
Cash flows from financing activities:
Net proceeds from issuance of senior unsecured 2024 Euro Notes - net of debt costs of $1,556	152,134
Net proceeds from issuance of 2022 secured notes - net of debt costs of $1,363		69,861
Dividends paid	(112,647)	(97,887)	(81,657)
Principal payments of finance lease obligations	(9,097)	(10,286)	(11,201)
Principal payments of installment payment agreement	(10,007)	(9,437)	(3,802)
Purchases of common stock		(6,564)	(1,829)
Proceeds from exercises of common stock options	1,637	1,768	1,222
Net cash provided by (used in) financing activities	22,020	(52,545)	(97,267)
Effect of exchange rate changes on cash	(542)	(2,357)	4,058
Net increase (decrease) in cash and cash equivalents	123,329	29,082	(27,308)
Cash and cash equivalents, beginning of period	276,093	247,011	274,319
Cash and cash equivalents, end of period	399,422	276,093	247,011
Supplemental disclosure of non-cash financing activities:
Cash paid for interest	56,022	48,918	47,032
Cash paid for income taxes	3,409	2,444	441
Supplemental disclosure of non-cash investing and financing activities:
Finance lease obligations incurred	14,307	20,050	22,595
PP&E obtained for installment payment agreement	11,255	9,925	9,027
Fair value of equipment acquired in leases	1,207
Non-cash component of network equipment obtained in exchange transactions	$ 978	$ 968	$ 3,861

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Senior unsecured 2024 notes
Cash flows from operating activities:
Debt costs	$ 1,556
Senior secured 2022 notes
Cash flows from operating activities:
Debt costs		$ 1,364

Description of the business and

Description of the business and summary of significant accounting policies:	12 Months Ended
	Dec. 31, 2019
Description of the business and summary of significant accounting policies:
Description of the business and summary of significant accounting policies:	1. Description of the business and summary of significant accounting policies: Reorganization and merger On May 15, 2014, pursuant to the Agreement and Plan of Reorganization (the “Merger Agreement”) by and among Cogent Communications Group, Inc. (“Group”), a Delaware corporation, Cogent Communications Holdings, Inc., a Delaware corporation (“Holdings”) and Cogent Communications Merger Sub, Inc., a Delaware corporation, Group adopted a new holding company organizational structure whereby Group is now a wholly owned subsidiary of Holdings. Holdings is a “successor issuer” to Group pursuant to Rule 12g-3(a) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). References to the “Company” for events that occurred prior to May 15, 2014 refer to Cogent Communications Group, Inc. and its subsidiaries and on and after May 15, 2014 the “Company” refers to Cogent Communications Holdings, Inc. and its subsidiaries. Description of business The Company is a Delaware corporation and is headquartered in Washington, DC. The Company is a facilities-based provider of low-cost, high-speed Internet access services, private network services and data center colocation space. The Company’s network is specifically designed and optimized to transmit packet routed data. The Company delivers its services primarily to small and medium-sized businesses, communications service providers and other bandwidth-intensive organizations in North America, Europe, Asia, Latin America and Australia. The Company offers on-net Internet access and private network services exclusively through its own facilities, which run from its network to its customers’ premises. The Company is not dependent on local telephone companies or cable TV companies to serve its customers for its on-net Internet access services because of its integrated network architecture. The Company offers its on-net services to customers located in buildings that are physically connected to its network. The Company’s on-net service consists of high-speed Internet access and private network services offered at speeds ranging from 100 megabits per second to 100 gigabits per second of bandwidth. The Company provides its on-net Internet access services and private network services to its corporate and net-centric customers. The Company’s corporate customers are located in multi-tenant office buildings and typically include law firms, financial services firms, advertising and marketing firms and other professional services businesses. The Company’s net-centric customers include bandwidth-intensive users such as other Internet service providers, telephone companies, cable television companies, web hosting companies, content delivery network companies and commercial content and application service providers. These net-centric customers obtain the Company’s services in colocation facilities and in the Company’s data centers. The Company operates data centers throughout North America and Europe that allow its customers to collocate their equipment and access the Company’s network. In addition to providing its on-net services, the Company provides Internet connectivity and private network services to customers that are not located in buildings directly connected to its network. The Company provides this off-net service primarily to corporate customers using other carriers’ facilities to provide the “last mile” portion of the link from the customers’ premises to the Company’s network. The Company also provides certain non-core services that resulted from acquisitions. The Company continues to support but does not actively sell these non-core services. Principles of consolidation The consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles and include the accounts of the Company and all of its wholly-owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. ​ 1. Description of the business and summary of significant accounting policies: (Continued) Use of estimates The preparation of consolidated financial statements in conformity with United States generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates. Allowance for doubtful accounts The Company establishes an allowance for doubtful accounts and other sales credit adjustments related to its trade receivables. Trade receivables are recorded at the invoiced amount and can bear interest. Allowances for sales credits are established through a reduction of revenue, while allowances for doubtful accounts are established through a charge to selling, general, and administrative expenses as bad debt expense. The Company assesses the adequacy of these reserves by evaluating factors, such as the length of time individual receivables are past due, historical collection experience, and changes in the credit worthiness of its customers. The Company also assesses the ability of specific customers to meet their financial obligations and establishes specific allowances related to these customers. If circumstances relating to specific customers change or economic conditions change such that the Company’s past collection experience and assessment of the economic environment are no longer appropriate, the Company’s estimate of the recoverability of its trade receivables could be impacted. Accounts receivable balances are written-off against the allowance for doubtful accounts after all means of internal collection activities have been exhausted and the potential for recovery is considered remote. The Company recognized bad debt expense, net of recoveries, of $4.1 million, $3.3 million and $3.7 million for the years ended December 31, 2019, 2018 and 2017, respectively. ​ 1. Description of the business and summary of significant accounting policies: (Continued) Recent Accounting Pronouncements— Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases ​ ​ ​ ​ ​ ​ ​ Year ​ ​ ​ Ended ​ ​ ​ December 31, 2019 ​ ​ ​ ​ ​ ​ Finance lease cost amortization of right-of-use assets $ 19,823 ​ Interest expense on finance lease liabilities ​ ​ 17,709 ​ Operating lease cost ​ ​ 15,688 ​ Total lease costs ​ ​ 53,220 ​ Other lease information ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ Operating cash flows from finance leases ​ ​ (17,959) ​ Operating cash flows from operating leases ​ ​ (17,106) ​ Financing cash flows from finance leases ​ ​ (9,097) ​ Right-of-use assets obtained in exchange for new finance lease liabilities ​ ​ 14,307 ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ ​ 9,754 ​ Weighted-average remaining lease term — finance leases (in years) ​ ​ 14.3 ​ Weighted-average remaining lease term — operating leases (in years) ​ ​ 21.9 ​ Weighted average discount rate — finance leases ​ ​ 11.0 % Weighted average discount rate — operating leases ​ ​ 5.6 % ​ ​ 1. Description of the business and summary of significant accounting policies: (Continued) Finance leases—fiber lease agreements The Company has entered into lease agreements with numerous providers of dark fiber under indefeasible-right-of use agreements (“IRUs). These IRUs typically have initial terms of 15 -20 The future minimum payments (principal and interest) under these finance leases are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 25,459 2021 ​ ​ 24,993 2022 ​ ​ 23,700 2023 ​ ​ 22,596 2024 ​ ​ 22,715 Thereafter ​ ​ 220,725 ​ ​ ​ ​ Total minimum finance lease obligations ​ ​ 340,188 Less—amounts representing interest ​ ​ (170,399) ​ ​ ​ ​ Present value of minimum finance lease obligations ​ ​ 169,789 Current maturities ​ ​ (8,154) ​ ​ ​ ​ Finance lease obligations, net of current maturities ​ $ 161,635 ​ ​ 1. Description of the business and summary of significant accounting policies: (Continued) Operating leases The Company leases office space and certain data center facilities under operating leases. In certain cases the Company also enters into short term operating leases for dark fiber. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments under the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the reasonably certain lease term. The implicit rates within the Company’s operating leases are generally not determinable and the Company uses its incremental borrowing rate at the lease commencement date to determine the present value of its lease payments. The determination of the Company’s incremental borrowing rate requires judgment. The Company determines its incremental borrowing rate for each lease using its current borrowing rate, adjusted for various factors including level of collateralization and term to align with the term of the lease. The determination of the Company's incremental borrowing rate requires judgment. The Company determines its incremental borrowing rate for each lease using its current borrowing rate, adjusted for various factors including level of collateralization and term to align with the term of the lease. Certain of the Company’s leases include options to extend or terminate the lease. The Company establishes the number of renewal option periods used in determining the operating lease term based upon its assessment at the inception of the operating lease of the number of option periods for which failure to renew the lease imposes a penalty in such amount that renewal appears to be reasonably certain. The option to renew may be automatic, at the option of the Company or mutually agreed to between the landlord or dark fiber provider and the Company. Once the Company has accepted the related fiber route or the facility lease term has begun, the present value of the aggregate future minimum operating lease payments is recorded as an operating lease liability and a right-of-use leased asset. Lease incentives and deferred rent liabilities for facilities operating leases are presented with the right-of-use leased asset. Lease expense for lease payments is recognized on a straight-line basis over the term of the lease. The future minimum payments under these operating lease agreements are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 15,075 2021 ​ ​ 13,788 2022 ​ ​ 12,211 2023 ​ ​ 11,376 2024 ​ ​ 9,903 Thereafter ​ ​ 98,542 ​ ​ ​ ​ Total minimum operating lease obligations ​ ​ 160,895 Less—amounts representing interest ​ ​ (64,104) ​ ​ ​ ​ Present value of minimum operating lease obligations ​ ​ 96,791 Current maturities ​ ​ (10,101) ​ ​ ​ ​ Lease obligations, net of current maturities ​ $ 86,690 ​ ​ 1. Description of the business and summary of significant accounting policies: (Continued) Revenue recognition The Company recognizes revenue under ASU No. 2014-09, Revenue from Contracts with Customers The Company’s service offerings consist of on-net and off-net telecommunications services. Fixed fees are billed monthly in advance and usage fees are billed monthly in arrears. Amounts billed are due upon receipt and contract lengths range from month to month to 60 months . The Company satisfies its performance obligations to provide services to customers over time as the services are rendered. In accordance with ASC 606, revenue is recognized when a customer obtains the promised service. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these services. The Company has adopted the practical expedient related to certain performance obligation disclosures since it has a right to consideration from its customer in an amount that corresponds directly with the value to the customer of the Company’s performance completed to date. To achieve this core principle, the Company follows the following five steps: 1) Identification of the contract, or contracts with a customer 2) Identification of the performance obligations in the contract 3) Determination of the transaction price 4) Allocation of the transaction price to the performance obligations in the contract 5) Recognition of revenue when, or as, we satisfy a performance obligation Fees billed in connection with customer installations are deferred (as deferred revenue) and recognized as noted above. To the extent a customer contract is terminated prior to its contractual end the customer is subject to termination fees. The Company vigorously seeks payment of these amounts. The Company recognizes revenue for these amounts as they are collected. Service revenue recognized from amounts in deferred revenue (contract liabilities) at the beginning of the period during the year ended December 31, 2019 was $4.4 million and during the year ended December 31, 2018 was $5.0 million. Amortization expense for contract costs was $17.3 million for the year ended December 31, 2019 and $16.8 million for the year ended December 31, 2018. ​ 1. Description of the business and summary of significant accounting policies: (Continued) Gross receipts taxes, universal service fund and other surcharges Revenue recognition standards include guidance relating to taxes or surcharges assessed by a governmental authority that are directly imposed on a revenue-producing transaction between a seller and a customer and may include, but are not limited to, gross receipts taxes, excise taxes, Universal Service Fund fees and certain state regulatory fees. Such charges may be presented gross or net based upon the Company’s accounting policy election. The Company records certain excise taxes and surcharges on a gross basis and includes them in its revenues and costs of network operations. Excise taxes and surcharges billed to customers and recorded on a gross basis (as service revenue and network operations expense) were $14.9 million, $12.5 million, and $10.9 million for the years ended December 31, 2019, 2018 and 2017, respectively. Network operations Network operations expenses include the costs of personnel and related operating expenses associated with service delivery, network management, and customer support, network facilities costs, fiber and equipment maintenance fees, leased circuit costs, access fees paid to building owners and certain excise taxes and surcharges recorded on a gross basis. The Company estimates its accruals for any disputed leased circuit obligations based upon the nature and age of the dispute. Network operations costs are impacted by the timing and amounts of disputed circuit costs. The Company generally records these disputed amounts when billed by the vendor and reverses these amounts when the vendor credit has been received or the dispute has otherwise been resolved. The Company does not allocate depreciation and amortization expense to its network operations expense. Foreign currency translation adjustment and comprehensive income The consolidated financial statements of the Company’s non-US operations are translated into US dollars using the period-end foreign currency exchange rates for assets and liabilities and the average foreign currency exchange rates for revenues and expenses. Gains and losses on translation of the accounts are accumulated and reported as a component of other comprehensive income in stockholders’ equity. The Company’s only components of “other comprehensive income” are currency translation adjustments for all periods presented. The Company considers the majority of its investments in its foreign subsidiaries to be long-term in nature. The Company’s foreign exchange transaction gains (losses) are included within interest income and other on the consolidated statements of comprehensive income. Financial instruments The Company considers all highly liquid investments with an original maturity of three months or less at purchase to be cash equivalents. The Company determines the appropriate classification of its investments at the time of purchase and evaluates such designation at each balance sheet date. At December 31, 2019 and December 31, 2018, the carrying amount of cash and cash equivalents, accounts receivable, prepaid and other current assets, accounts payable, and accrued expenses approximated fair value because of the short-term nature of these instruments. The Company measures its cash equivalents at amortized cost, which approximates fair value based upon quoted market prices (Level 1). Based upon recent trading prices (Level 2—market approach) at December 31, 2019 the fair value of the Company’s $189.2 million senior unsecured notes was $191.8 million , the fair value of the Company's $445.0 million senior secured notes was $466.1 million and the fair value of the Company’s €135.0 million ($151.4 million) senior unsecured notes was $155.4 million. ​ 1. Description of the business and summary of significant accounting policies: (Continued) Concentrations of credit risk The Company's assets that are exposed to credit risk consist of its cash and cash equivalents, other assets and accounts receivable. As of December 31, 2019 and 2018, the Company's cash equivalents were invested in demand deposit accounts, overnight investments and money market funds. The Company places its cash equivalents in instruments that meet high-quality credit standards as specified in the Company's investment policy guidelines. Accounts receivable are due from customers located in major metropolitan areas in the United States, Europe, Canada, Mexico, Asia, Latin America and Australia. Receivables from the Company's net-centric (wholesale) customers are generally subject to a higher degree of credit risk than the Company's corporate customers. The Company relies upon an equipment vendor for the majority of its network equipment and is also dependent upon many third-party fiber providers for providing its services to its customers. Property and equipment Property and equipment are recorded at cost and depreciated once deployed using the straight-line method over the estimated useful lives of the assets. Useful lives are determined based on historical usage with consideration given to technological changes and trends in the industry that could impact the asset utilization. System infrastructure costs include the capitalized compensation costs of employees directly involved with construction activities and costs incurred by third party contractors. Assets and liabilities under finance leases are recorded at the lesser of the present value of the aggregate future minimum lease payments or the fair value of the assets under lease. Leasehold improvements include costs associated with building improvements. The Company determines the number of renewal option periods, if any, included in the lease term for purposes of amortizing leasehold improvements and the lease term of its finance leases based upon its assessment at the inception of the lease for which the failure to renew the lease imposes a penalty on the Company in such amount that a renewal appears to be reasonably assured. Expenditures for maintenance and repairs are expensed as incurred. Depreciation and amortization periods are as follows: ​ ​ ​ ​ Type of asset Depreciation or amortization period Indefeasible rights of use (IRUs) Shorter of useful life or the IRU lease agreement; generally 15 Network equipment 3 Leasehold improvements Shorter of lease term, including reasonably assured renewal periods, or useful life Software 5 years Owned buildings 40 years Office and other equipment 3 to 7 years System infrastructure 5 ​ ​ 1. Description of the business and summary of significant accounting policies: (Continued) Long-lived assets The Company’s long-lived assets include property and equipment. These long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Impairment is determined by comparing the carrying value of these long-lived assets to management’s probability weighted estimate of the future undiscounted cash flows expected to result from the use of the assets. In the event an impairment exists, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the asset, which would be determined by using quoted market prices or valuation techniques such as the discounted present value of expected future cash flows, appraisals, or other pricing models. In the event there are changes in the planned use of the Company’s long-term assets or the Company’s expected future undiscounted cash flows are reduced significantly, the Company’s assessment of its ability to recover the carrying value of these assets could change. Equity-based compensation The Company recognizes compensation expense for its share-based payments granted to its employees based on their grant date fair values with the expense being recognized on a straight-line basis over the requisite service period. The Company begins recording equity-based compensation expense related to performance awards when it is considered probable that the performance conditions will be met and for market based awards compensation cost is recognized if the service condition is satisfied even if the market condition is not satisfied. Equity-based compensation expense is recognized in the statement of operations in a manner consistent with the classification of the employee's salary and other compensation. Income taxes The Company’s deferred tax assets or liabilities are computed based upon the differences between financial statement and income tax bases of assets and liabilities using the enacted marginal tax rate. Deferred income tax expenses or benefits are based upon the changes in the assets or liability from period to period. At each balance sheet date, the Company assesses the likelihood that it will be able to realize its deferred tax assets. Valuation allowances are established when management determines that it is “more likely than not” that some portion or all of the deferred tax asset may not be realized. The Company considers all available positive and negative evidence in assessing the need for a valuation allowance including its historical operating results, ongoing tax planning, and forecasts of future taxable income, on a jurisdiction by jurisdiction basis. The Company reduces its valuation allowance if the Company concludes that it is “more likely than not” that it would be able to realize its deferred tax assets. Management determines whether a tax position is more likely than not to be sustained upon examination based on the technical merits of the position. Once it is determined that a position meets this recognition threshold, the position is measured to determine the amount of benefit to be recognized in the financial statements. The Company adjusts its estimated liabilities for uncertain tax positions periodically because of ongoing examinations by, and settlements with, the various taxing authorities, as well as changes in tax laws, regulations and interpretations. The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of its income tax expense. Basic and diluted net income per common share Basic earnings per share (“EPS”) excludes dilution for common stock equivalents and is computed by dividing net income or (loss) available to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted EPS is based on the weighted-average number of shares of common stock outstanding during each period, adjusted for the effect of dilutive common stock equivalents. ​ 1. Description of the business and summary of significant accounting policies: (Continued) Shares of restricted stock are included in the computation of basic EPS as they vest and are included in diluted EPS, to the extent they are dilutive, determined using the treasury stock method. The following details the determination of the diluted weighted average shares: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended Year Ended Year Ended ​ ​ December 31, ​ December 31, ​ December 31, ​ ​ 2019 ​ 2018 ​ 2017 Weighted average common shares—basic 45,542,315 45,280,161 44,855,263 Dilutive effect of stock options 32,222 33,134 31,534 Dilutive effect of restricted stock 505,858 467,659 297,406 Weighted average common shares—diluted 46,080,395 45,780,954 45,184,203 ​ The following details unvested shares of restricted common stock as well as the anti-dilutive effects of stock options and restricted stock awards outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, December 31, ​ ​ 2019 ​ 2018 ​ 2017 Unvested shares of restricted common stock ​ 1,283,281 ​ 1,187,586 ​ 1,112,151 Anti-dilutive options for common stock ​ 39,608 ​ 53,114 ​ 47,513 Anti-dilutive shares of restricted common stock 348 3,545 ​ 201 ​ Recent Accounting Pronouncements—to be Adopted In June 2016, the FASB issued ASU No. 2016-13, “ Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments.

Property and equipment_

Property and equipment:	12 Months Ended
	Dec. 31, 2019
Property and equipment:
Property and equipment:	2. Property and equipment: Property and equipment consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Owned assets: ​ ​ ​ ​ ​ ​ Network equipment ​ $ 566,936 ​ $ 538,761 Leasehold improvements ​ 227,388 ​ 214,495 System infrastructure ​ 134,726 ​ 124,018 Software ​ 10,035 ​ 9,963 Office and other equipment ​ 18,169 ​ 16,711 Building ​ 1,252 ​ 1,277 Land ​ 106 ​ 108 ​ ​ 958,612 ​ 905,333 Less—Accumulated depreciation and amortization ​ (790,033) ​ (736,356) ​ ​ 168,579 ​ 168,977 Assets under finance leases: ​ ​ ​ ​ ​ ​ IRUs ​ 408,170 ​ 395,170 Less—Accumulated depreciation and amortization ​ (207,820) ​ (188,822) ​ ​ 200,350 ​ 206,348 Property and equipment, net ​ $ 368,929 ​ $ 375,325 ​ ​ 2. Property and equipment: (Continued) Depreciation and amortization expense related to property and equipment and finance leases was $80.2 million, $81.2 million and $75.9 million, for 2019, 2018 and 2017, respectively. The Company capitalizes the compensation cost of employees directly involved with its construction activities. In 2019, 2018 and 2017, the Company capitalized compensation costs of $10.7 million, $10.5 million and $9.7 million respectively. These amounts are included in system infrastructure costs. Exchange agreement In 2019, 2018 and 2017 the Company exchanged certain used network equipment and cash consideration for new network equipment. The fair value of the new network equipment received was estimated to be $3.3 million, $3.2 million and $9.1 million resulting in gains of $1.0 million, $1.0 million and $3.9 million respectively. The estimated fair value of the equipment received was based upon the cash consideration price the Company pays for the new network equipment on a standalone basis (Level 3). Installment payment agreement The Company has entered into an installment payment agreement (“IPA”) with a vendor. Under the IPA the Company may purchase network equipment in exchange for interest free note obligations each with a twenty-four month term. There are no payments under each note obligation for the first six months followed by eighteen equal installment payments for the remaining eighteen month term. As of December 31, 2019 and December 31, 2018, there was $12.5 million and $11.2 million, respectively, of note obligations outstanding under the IPA, secured by the related equipment. The Company recorded the assets purchased and the present value of the note obligation utilizing an imputed interest rate. The resulting discounts totaling $0.4 million and $0.4 million as of December 31, 2019 and December 31, 2018, respectively, under the note obligations are being amortized over the note term using the effective interest rate method.

Accrued and other liabilities_

Accrued and other liabilities:	12 Months Ended
	Dec. 31, 2019
Accrued and other liabilities:
Accrued and other liabilities:	3. Accrued and other liabilities: Accrued and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2019 2018 Operating accruals ​ $ 23,695 ​ $ 24,020 Deferred revenue—current portion ​ 4,316 ​ 4,504 Payroll and benefits ​ 6,613 ​ 7,695 Taxes—non-income based ​ 6,053 ​ 4,212 Interest ​ 10,624 ​ 11,000 Total ​ $ 51,301 ​ $ 51,431 ​

Long-term debt_

Long-term debt:	12 Months Ended
	Dec. 31, 2019
Long-term debt:
Long-term debt:	4. Long-term debt: Issuance of 2024 Notes On June 25, 2019, Group completed an offering of €135.0 million aggregate principal amount of 4.375% senior unsecured notes ("The 2024 Notes") due on June 30, 2024. The net proceeds from the offering, after deducting offering expenses, were approximately $152.1 million. The Company expects to use the proceeds for general corporate purposes and/or to repurchase the Company’s common stock or for special or recurring dividends to the Company’s stockholders. The 2024 Notes are guaranteed (the “Guarantees”) on a senior unsecured basis, jointly and severally, by the Company’s material domestic subsidiaries, subject to certain exceptions, and by the Company (collectively, the “Guarantors”). Under certain circumstances, the Guarantors may be released from these Guarantees without the consent of the holders of the 2024 Notes. ​ 4. Long-term debt: (Continued) The 2024 Notes and the Guarantees are Group’s and the Guarantors’ senior unsecured obligations. The 2024 Notes and the Guarantees are effectively subordinated to all of Group’s and the Guarantors’ existing and future secured indebtedness to the extent of the value of the collateral securing such indebtedness, and are structurally subordinated to all indebtedness and other liabilities of subsidiaries that are not Guarantors. Without giving effect to collateral arrangements, the 2024 Notes and the Guarantees rank pari passu in right of payment with Group’s and the Guarantors’ existing and future senior indebtedness. The 2024 Notes and the Guarantees rank contractually senior in right of payment to all of Group’s and the Guarantors’ existing and future subordinated indebtedness. The 2024 Notes were offered and sold only to persons reasonably believed to be qualified institutional buyers in an unregistered offering pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Act”), and to certain non-U.S. persons in transactions outside the United States in compliance with Regulation S under the Act. The 2024 Notes have not been registered under the Act, and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements. The 2024 Notes are listed on the Official List of The International Stock Exchange; however, there can be no assurance that the listing will be maintained. The 2024 Notes bear interest at a rate of 4.375% per annum. Interest began to accrue on the 2024 Notes on June 25, 2019 and will be paid semi-annually in arrears on June 30 and December 30 of each year, commencing on December 30, 2019. Unless earlier redeemed, the 2024 Notes will mature on June 30, 2024. The 2024 Notes were issued by Group, a subsidiary with a US dollar functional currency, and issued at par for €135.0 million ($153.7 million) on June 25, 2019. The 2024 Notes were issued in Euros and are reported in the Company’s reporting currency — US Dollars. As of December 31, 2019 the 2024 Notes were valued at $151.4 million resulting in an unrealized gain on foreign exchange of $2.3 million for the year ended December 31, 2019. Group may redeem some or all of the 2024 Notes at any time prior to June 30, 2021 at a price equal to 100% of the principal amount of the 2024 Notes, plus a “make-whole” premium as set forth in the indenture, plus accrued and unpaid interest, if any, to, but not including, the date of redemption. Thereafter, Group may redeem the 2024 Notes, in whole or in part, at a redemption price ranging from 102.188% to par (depending on the year), as set forth in the indenture. Group may also redeem up to 35% of the principal amount of the 2024 Notes using proceeds of certain equity offerings completed prior to June 30, 2021 at a redemption price equal to 104.375%, plus accrued and unpaid interest, if any, to, but not including, the date of redemption, subject to certain exceptions. Group may also redeem the 2024 Notes, in whole but not in part, in the event of certain changes in the tax laws of the United States (or any taxing authority in the United States). This redemption would be at 100% of the principal amount of the 2024 Notes to be redeemed (plus any accrued interest and additional amounts then payable with respect to the 2024 Notes to, but not including, the redemption date). If Group undergoes specific kinds of change in control accompanied by certain ratings events, it will be required to offer to repurchase the 2024 Notes from holders at a price equal to 101% of the principal amount thereof, plus accrued and unpaid interest, if any, to, but not including, the date of repurchase. Additionally, if Group or any of its restricted subsidiaries sells assets and does not apply the proceeds from such sale in a certain manner or certain other events have not occurred, under certain circumstances, Group will be required to use the excess net proceeds to make an offer to purchase the 2024 Notes at an offer price in cash equal to 100% of the principal amount of the 2024 Notes, plus accrued and unpaid interest, if any, to, but not including, the repurchase date. In connection with any offer to purchase all or any of the 2024 Notes (including a change of control offer, asset sale offer or any tender offer), if holders of no less than 90% of the aggregate principal amount of the 2024 Notes validly tender their 2024 Notes, Group or a third party is entitled to redeem any remaining 2024 Notes at the price offered to each holder. ​ 4. Long-term debt: (Continued) The 2024 notes indenture includes covenants that restrict Group and its restricted subsidiaries’ ability to, among other things: incur indebtedness; issue certain preferred stock or similar equity securities; pay dividends or make other distributions in respect of, or repurchase or redeem, capital stock; make certain investments and other restricted payments, such as prepayment, redemption or repurchase of certain indebtedness; create liens; consolidate, merge, sell or otherwise dispose of all or substantially all of the assets of Group and its restricted subsidiaries taken as a whole; incur restrictions on the ability of a subsidiary to pay dividends or make other payments; and enter into transactions with affiliates. However, the covenants provide for certain exceptions to these restrictions and the Company is not subject to the covenants under the 2024 Notes indenture. Certain covenants will cease to apply to the 2024 Notes if, and for so long as, the 2024 Notes have investment grade ratings from any two of Moody’s Investors Service, Inc., Fitch Ratings, Inc. and S&P Global Ratings and so long as no default or event of default under the Indenture has occurred and is continuing. The principal amount of the 2024 Notes would become immediately due and payable upon the occurrence of certain bankruptcy or insolvency events involving Group or certain of its subsidiaries, and may be declared immediately due and payable by the trustee or the holders of at least 25% of the aggregate principal amount of the then-outstanding 2024 Notes upon the occurrence of certain events of default under the indenture. Senior secured notes -$445.0 million 2022 Notes In February 2015, Group issued $250.0 million of 5.375% senior secured notes due 2022 (the “2022 Notes”). The net proceeds from the offering were $248.6 million after deducting discounts and commissions and offering expenses. In December 2016, the Company issued an additional $125.0 million par value of its 2022 Notes at a premium of 100.375 % of par value. The Company received net proceeds of $124.3 million after deducting offering costs. In August 2018, the Company issued an additional $70.0 million par value of its 2022 Notes at a premium of 101.75% of par value. The Company received net proceeds of $69.9 million after deducting offering costs. The premium and offering costs are amortized to interest expense to the maturity date using the effective interest rate method. The net proceeds from these offerings are intended to be used for general corporate purposes. The 2022 Notes were sold in private offerings for resale to qualified institutional buyers pursuant to SEC Rule 144A and mature on March 1, 2022. Interest accrues at 5.375% and is paid semi-annually in arrears on March 1 and September 1 of each year. The indenture governing the 2022 Notes provides that the Company and each of the Company’s existing domestic subsidiaries and future material domestic subsidiaries guarantee the 2022 Notes, subject to certain exceptions and permitted liens. The 2022 Notes are also secured by a pledge of all of the equity interests in Group’s domestic subsidiaries and 65% of the equity interests in Group’s first-tier foreign subsidiaries. The 2022 Notes and the subsidiary guarantees will be the Company’s and the subsidiary guarantors’ senior indebtedness and will rank pari passu ​ 4. Long-term debt: (Continued) The 2022 Notes may be redeemed prior to December 1, 2021 (three months prior to the maturity date of the Notes) in whole or from time to time in part, at a redemption price equal to the sum of (1) 100% of the principal amount plus accrued and unpaid interest, if any, to, but not including, the redemption date, and (2) a make-whole premium, if any. The make-whole premium is the excess of (1) the net present value, on the redemption date, of the principal being redeemed or paid and the amount of interest (exclusive of interest accrued to the date of redemption) that would have been payable if such redemption had not been made, over (2) the aggregate principal amount of the notes being redeemed or paid. Net present value shall be determined by discounting, on a semi-annual basis, such principal and interest at the reinvestment rate (as determined in the indenture governing the 2022 Notes) from the respective dates on which such principal and interest would have been payable if such redemption had not been made. In addition, at any time on or after December 1, 2021 (three months prior to the maturity date of the 2022 Notes), the Issuer may redeem the 2022 Notes, in whole and or in part, at a redemption price equal to 100% of the principal amount of the 2022 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but not including, the redemption date. Senior unsecured notes—$189.2 million 2021 Notes On April 9, 2014, Cogent Communications Finance, Inc. ( “Cogent Finance”), a newly formed financing subsidiary of Group, completed an offering at par of $200.0 million in aggregate principal amount of 5.625% Senior Notes due 2021 (the “2021 Notes”). The 2021 Notes were sold in private offerings for resale to qualified institutional buyers pursuant to SEC Rule 144A and will mature on April 15, 2021. Interest is paid semi-annually on April 15 and October 15. Cogent Finance merged with Group, with Group continuing as the surviving corporation (the “Finance Merger”). At the time of consummation of the Finance Merger, Group assumed the obligations of Cogent Finance under the 2021 Notes and the indenture governing the 2021 Notes (the “Indenture”) and Group and each of Group’s domestic subsidiaries became party to the Indenture pursuant to a supplemental indenture to the Indenture and the obligations under the Indenture became obligations solely of Group and each of Group’s domestic subsidiaries. Holdings also provided a guarantee of the 2021 Notes but Holdings is not subject to the covenants under the Indenture. The net proceeds from the offering were $195.8 million after deducting commissions and offering expenses. The net proceeds from the offering are intended to be used for general corporate purposes. In the second quarter of 2016, the Company paid $10.9 million for the purchase of $10.8 million of par value and accrued interest on its 2021 Notes reducing the principal amount to $189.2 million and resulting in a loss on extinguishment of $0.2 million. The loss resulted from the write off of the remaining unamortized debt issuance costs related to the purchased notes. The 2021 Notes bear interest at a rate of 5.625% per year and will mature on April 15, 2021. Interest is paid semi-annually on April 15 and October 15. The 2021 Notes are senior unsecured obligations of Group and are guaranteed on a senior unsecured basis by Holdings. The 2021 Notes are effectively subordinated in right of payment to all of Group’s and each guarantor’s secured indebtedness and future secured indebtedness, if any, to the extent of the value of the assets securing such indebtedness. The 2021 Notes are equal in right of payment with Group’s and each guarantor’s unsecured indebtedness that is not subordinated in right of payment to the 2021 Notes. The 2021 Notes rank senior in right of payment to Group’s and each guarantor’s future subordinated debt, if any; and are structurally subordinated in right of payment to all indebtedness and other liabilities of any of the Group’s subsidiaries that are not guarantors, which only consist of immaterial subsidiaries and foreign subsidiaries that do not guarantee other indebtedness of Group. ​ 4. Long-term debt: (Continued) Group may also redeem the 2021 Notes, in whole or in part, at any time on or after April 15, 2017 at the applicable redemption prices specified under the indenture governing the 2021 Notes plus accrued and unpaid interest, if any, to the date of redemption. The redemption prices (expressed as a percentage of the principal amount) are 104.219% during the 12-month period beginning on April 15, 2017, 102.813% during the 12-month period beginning on April 15, 2018, 101.406% during the 12-month period beginning on April 15, 2019 and 100.0% during the 12-month period beginning on April 15, 2020 and thereafter. If Group experiences specific kinds of changes of control, Group must offer to repurchase all of the 2021 Notes at a purchase price of 101.0% of their principal amount, plus accrued and unpaid interest, if any, to the repurchase date. Limitations under the indentures The indentures governing the 2024 Notes, 2022 Notes and 2021 Notes, among other things, limit the Company’s ability to incur indebtedness; to pay dividends or make other distributions; to make certain investments and other restricted payments; to create liens; consolidate, merge, sell or otherwise dispose of all or substantially all of its assets; to incur restrictions on the ability of a subsidiary to pay dividends or make other payments; and to enter into certain transactions with its affiliates. Limitations on the ability to incur additional indebtedness (excluding IRU agreements incurred in the normal course of business) include a restriction on incurring additional indebtedness if the Company’s consolidated leverage ratio, as defined in the indentures, is greater than 6.0 for the 2024 Notes and greater than 5.0 for the 2022 Notes and 2021 Notes. Limitations on the ability to incur additional secured indebtedness include a restriction on incurring additional secured indebtedness if the Company’s consolidated secured leverage ratio, as defined in the indentures, is greater than 4.0 for the 2024 Notes and greater than 3.5 for the 2022 Notes and 2021 Notes. The indentures prohibit certain payments, such as dividends and stock purchases, when the Company’s consolidated leverage ratio, as defined by the indentures, is greater than 4.25. A certain amount of such unrestricted payments is permitted notwithstanding this prohibition. The unrestricted payment amount may be increased by the Company’s consolidated cash flow, as defined in the indentures, as long as the Company’s consolidated leverage ratio is less than 4.25. The Company’s consolidated leverage ratio was above 4.25 as of December 31, 2019. As of December 31, 2019, a total of $110.3 million (primarily held by Holdings in cash and cash equivalents) was permitted for investment payments including dividends and stock purchases. Long-term debt maturities The aggregate future contractual maturities of long-term debt were as follows as of December 31, 2019 (in thousands): ​ ​ ​ ​ For the year ending December 31, ​ ​ 2020 ​ $ 9,413 2021 ​ 192,299 2022 ​ 445,000 2023 ​ — 2024 ​ 151,411 Thereafter ​ — Total ​ $ 798,123 ​

Income taxes_

Income taxes:	12 Months Ended
	Dec. 31, 2019
Income taxes:
Income taxes:	5. Income taxes: On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (the "TCJA"). The TCJA amended the Internal Revenue Code and reduced the corporate tax rate from a maximum of 35% to a flat 21% rate. The rate reduction was effective on January 1, 2018. The Company's net deferred tax assets represent a decrease in corporate taxes expected to be paid in the future. Under generally accepted accounting principles deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The Company's net deferred tax asset was determined based on the current enacted federal tax rate of 35% prior to the passage of the Act. As a result of the reduction in the corporate income tax rate from 35% to 21% and other provisions under the TCJA, the Company made reasonable estimates of the effects of the TCJA and revalued its net deferred tax asset at December 31, 2017 resulting in a reduction in the value of its net deferred tax asset of approximately $9.0 million and recorded a transition tax of $2.3 million related to its foreign operations for a total of $11.3 million, which was recorded as additional noncash income tax expense in the year ended December 31, 2017. As of December 31, 2018, the Company had collected all of the necessary data to complete its analysis of the effect of the TCJA on its underlying deferred income taxes and recorded a $0.1 million reduction in the value to its net deferred tax asset. The TCJA subjects a U.S. shareholder to current tax on global intangible low-taxed income earned by certain foreign subsidiaries. FASB Staff Q&A, Topic 740, No. 5, "Accounting for Global Intangible Low-Taxed Income", states that the Company is permitted to make an accounting policy election to either recognize deferred income taxes for temporary basis differences expected to reverse as global intangible low-taxed income in future years or provide for the income tax expense related to such income in the year the income tax is incurred. The Company has made an accounting policy to record these income taxes as a period cost in the year the income tax in incurred. The components of income (loss) before income taxes consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Domestic ​ $ 72,773 ​ $ 63,878 ​ $ 52,250 Foreign ​ (20,099) ​ (22,496) ​ (21,132) Total income before income taxes ​ $ 52,674 ​ $ 41,382 ​ $ 31,118 ​ The income tax expense is comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ — ​ $ — ​ $ — State ​ (2,647) ​ (1,522) ​ (353) Foreign ​ (370) ​ (75) ​ (209) Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ (10,899) ​ (9,746) ​ (24,150) State ​ (1,285) ​ (802) ​ (430) Foreign ​ 47 ​ (570) ​ (100) Total income tax expense ​ $ (15,154) ​ $ (12,715) ​ $ (25,242) ​ ​ 5. Income taxes: (Continued) Our consolidated temporary differences comprising our net deferred tax assets are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Deferred Tax Assets: ​ ​ ​ ​ ​ ​ Net operating loss carry-forwards ​ $ 255,269 ​ $ 255,235 Tax credits ​ 2,261 ​ 2,458 Equity-based compensation ​ ​ 4,116 ​ ​ 3,322 Operating leases ​ ​ 32,289 ​ ​ — Total gross deferred tax assets ​ 293,935 ​ 261,015 Valuation allowance ​ ​ (131,069) ​ ​ (126,579) ​ ​ ​ 162,866 ​ ​ 134,436 Deferred Tax Liabilities: ​ ​ ​ ​ ​ ​ Depreciation and amortization ​ 34,884 ​ 29,769 Accrued liabilities and other ​ 107,711 ​ 101,934 Right-of-use assets ​ ​ 29,670 ​ ​ — Gross deferred tax liabilities ​ 172,265 ​ 131,703 Net deferred tax (liabilities) assets ​ $ (9,399) ​ $ 2,733 ​ At each balance sheet date, the Company assesses the likelihood that it will be able to realize its deferred tax assets. The Company considers all available positive and negative evidence in assessing the need for a valuation allowance. The Company maintains a full valuation allowance against certain of its deferred tax assets consisting primarily of net operating loss carryforwards related to its foreign operations in Canada, Europe, Asia, Latin America and Australia and net operating losses in the United States that are limited for use under Section 382 of the Internal Revenue Code. As of December 31, 2019, the Company has combined net operating loss carry-forwards of $994.0 million. This amount includes federal net operating loss carry-forwards in the United States of $97.6 million, net operating loss carry-forwards related to its European, Mexican, Canadian and Asian operations of $890.1 million, $3.3 million, $1.8 million and $1.0 million, respectively. Section 382 of the Internal Revenue Code in the United States limits the utilization of net operating losses when ownership changes, as defined by that section, occur. The Company has performed an analysis of its Section 382 ownership changes and has determined that the utilization of certain of its net operating loss carryforwards in the United States is limited based on the annual Section 382 limitation and remaining carryforward period. Of the net operating losses available at December 31, 2019 in the United States $38.4 million are limited for use under Section 382. Net operating loss carryforwards outside of the United States totaling $896.4 million are not subject to limitations similar to Section 382. The net operating loss carryforwards in the United States will expire, if unused, between 2025 and 2036. The net operating loss carry-forwards related to the Company's Mexican, Asian and Canadian operations will expire if unused, between 2020 and 2029. The net operating loss carry-forwards related to the Company's European operations include $744.6 million that do not expire and $145.5 million that expire between 2020 and 2035. Other than the $2.3 million transition tax recorded in the year ended December 31, 2017 as a result of its foreign earnings the Company has not provided for United States deferred income taxes or foreign withholding taxes on its undistributed earnings for certain non-US subsidiaries earnings or cumulative translation adjustments because these earnings and adjustments are intended to be permanently reinvested in operations outside the United States. It is not practical to determine the amount of the unrecognized deferred tax liability on such undistributed earnings or cumulative translation adjustments. ​ 5. Income taxes: (Continued) In the normal course of business the Company takes positions on its tax returns that may be challenged by taxing authorities. The Company evaluates all uncertain tax positions to assess whether the position will more likely than not be sustained upon examination. If the Company determines that the tax position is not more likely than not to be sustained, the Company records a liability for the amount of the benefit that is not more likely than not to be realized when the tax position is settled. The Company does not have a liability for uncertain tax positions at December 31, 2019 and does not expect that its liability for uncertain tax positions will materially increase during the twelve months ended December 31, 2020, however, actual changes in the liability for uncertain tax positions could be different than currently expected. If recognized, changes in the Company's total unrecognized tax benefits would impact the Company's effective income tax rate. The Company or one of its subsidiaries files income tax returns in the US federal jurisdiction and various state and foreign jurisdictions. The Company is subject to US federal tax and state tax examinations for years 2004 to 2019. The Company is subject to tax examinations in its foreign jurisdictions generally for years 2005 to 2019. The following is a reconciliation of the Federal statutory income taxes to the amounts reported in the financial statements (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Federal income tax expense at statutory rates ​ $ (11,061) ​ $ (8,690) ​ $ (10,892) Effect of: ​ ​ ​ ​ ​ ​ ​ ​ ​ State income taxes, net of federal benefit ​ (2,973) ​ (2,665) ​ (2,244) Impact of foreign operations ​ (11) ​ (146) ​ 74 Non-deductible expenses ​ (592) ​ (1,274) ​ (1,350) Federal tax rate change ​ — ​ — ​ (9,046) Tax effect of TCJA from foreign earnings ​ (28) ​ (130) ​ (2,296) Other ​ (581) ​ (645) ​ 239 Changes in valuation allowance ​ 92 ​ 835 ​ 273 Income tax expense ​ $ (15,154) ​ $ (12,715) ​ $ (25,242) ​

Commitments and contingencies_

Commitments and contingencies:	12 Months Ended
	Dec. 31, 2019
Commitments and contingencies:
Commitments and contingencies:	6. Commitments and contingencies: Current and potential litigation In accordance with the accounting guidance for contingencies, the Company accrues its estimate of a contingent liability when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Where it is probable that a liability has been incurred and there is a range of expected loss for which no amount in the range is more likely than any other amount, the Company accrues at the low end of the range. The Company reviews its accruals at least quarterly and adjusts them to reflect the impact of negotiations, settlements, rulings, advice of legal counsel, and other information and events pertaining to a particular matter. The Company has taken certain positions related to its obligations for leased circuits for which it is reasonably possible could result in a loss of up to $3.1 million in excess of the amount accrued at December 31, 2019. The Company is engaged in an arbitration proceeding in Spain in which a former provider of optical fiber to the Company is seeking approximately $9.0 million for Company’s early termination of the optical fiber leases, which amount the Company accrued in 2015. The Company has counterclaimed for damages and is contesting its obligation to pay the termination liability. The arbitration is being conducted by the Civil and Commercial Arbitration Court (CIMA) in Madrid, Spain. In the ordinary course of business the Company is involved in other legal activities and claims. Because such matters are subject to many uncertainties and the outcomes are not predictable with assurance, the liability related to these legal actions and claims cannot be determined with certainty. Management does not believe that such claims and actions will have a material impact on the Company’s financial condition or results of operations. Judgment is required in estimating the ultimate outcome of any dispute resolution process, as well as any other amounts that may be incurred to conclude the negotiations or settle any litigation. Actual results may differ from these estimates under different assumptions or conditions and such differences could be material. Leases The Company enters into leases for network equipment sites and data center facilities. Future minimum annual payments under these arrangements are as follows (in thousands): ​ ​ ​ ​ ​ For the year ending December 31, ​ ​ 2020 ​ $ 21,044 2021 ​ 10,983 2022 ​ 5,362 2023 ​ 3,348 2024 ​ 1,511 Thereafter ​ 1,944 ​ ​ $ 44,192 ​ Expenses related to these arrangements were $20.6 million in 2019, $20.8 million in 2018 and $19.2 million in 2017. Short-term lease expense as required to be disclosed under ASU 2016-02 was $0.9 million for the year ended December 31, 2019. Unconditional purchase obligations Unconditional purchase obligations for equipment and services totaled $7.6 million at December 31, 2019. As of December 31, 2019, the Company had also committed to additional dark fiber IRU capital and operating lease agreements totaling $20.3 million in future payments to be paid over periods of up to 20 years. These obligations begin when the related fiber is accepted, which is generally expected to occur in 2020. Future minimum payments under these obligations are $4.6 million, $0.6 million, $0.7 million, $0.7 million and $0.6 million for the years ending December 31, 2020 to December 31, 2024, respectively, and $13.0 million, thereafter. Defined contribution plan The Company sponsors a 401(k) defined contribution plan that provides for a Company matching payment. The Company matching payments were paid in cash and were $0.8 million for 2019, $0.8 million for 2018 and $0.7 million for 2017.

Stockholders' equity_

Stockholders' equity:	12 Months Ended
	Dec. 31, 2019
Stockholders' equity:
Stockholders' equity:	7. Stockholders’ equity: Authorized shares The Company has 75.0 million shares of authorized $0.001 par value common stock and 10,000 authorized but unissued shares of $0.001 par value preferred stock. The holders of common stock are entitled to one vote per common share and, subject to any rights of any series of preferred stock, dividends may be declared and paid on the common stock when determined by the Company’s Board of Directors. Common stock buybacks The Company’s Board of Directors has approved $50.0 million for purchases of the Company’s common stock under a buyback program (the “Buyback Program”). At December 31, 2019, there was $34.9 million remaining for purchases under the Buyback Program. During 2018 and 2017 the Company purchased 147,995 and 46,750 shares of its common stock for $6.6 million and $1.8 million, respectively. These shares of common stock were subsequently retired.There were no purchases of common stock in 2019. Dividends on common stock Dividends are recorded as a reduction to retained earnings. Dividends on unvested restricted shares of common stock are paid as the awards vest. The Company’s initial quarterly dividend payment was made in the third quarter of 2012. The payment of any future dividends and any other returns of capital, including stock buybacks, will be at the discretion of the Company’s Board of Directors and may be reduced, eliminated or increased and will be dependent upon the Company’s financial position, results of operations, available cash, cash flow, capital requirements, limitations under the Company’s debt indentures and other factors deemed relevant by the Company’s Board of Directors. The Company is a Delaware Corporation and under the General Corporate Law of the State of Delaware distributions may be restricted including a restriction that distributions, including stock purchases and dividends, do not result in an impairment of a corporation’s capital, as defined under Delaware Law. The indentures governing the Company’s notes limit the Company’s ability to return cash to its stockholders.

Stock option and award plan_

Stock option and award plan:	12 Months Ended
	Dec. 31, 2019
Stock option and award plan:
Stock option and award plan:	8. Stock option and award plan: Incentive award plan The Company grants restricted stock and options for common stock under its award plan, as amended (the “Award Plan”). Stock options granted under the Award Plan generally vest over a four-year period and have a term of ten years. Grants of shares of restricted stock granted under the Award Plan generally vest over periods ranging from three ​ 8. Stock option and award plan: (Continued) The accounting for equity-based compensation expense requires the Company to make estimates and judgments that affect its financial statements. These estimates for stock options include the following. Expected Dividend Yield—The Company uses an expected dividend yield based upon expected annual dividends and the Company’s stock price. Expected Volatility—The Company uses its historical volatility for a period commensurate with the expected term of the option. Risk-Free Interest Rate—The Company uses the zero coupon US Treasury rate during the quarter having a term that most closely resembles the expected term of the option. Expected Term of the Option—The Company estimates the expected life of the option term by analyzing historical stock option exercises. Forfeiture Rates—The Company estimates its forfeiture rate based on historical data with further consideration given to the class of employees to whom the options or shares were granted. The weighted-average per share grant date fair value of options was $8.92 in 2019, $8.45 in 2018 and $7.06 in 2017. The following assumptions were used for determining the fair value of options granted in the three years ended December 31, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, ​ Black-Scholes Assumptions 2019 2018 2017 Dividend yield 4.5 % 4.6 % 4.1 % Expected volatility 28.3 % 28.7 % 27.1 % Risk-free interest rate 2.5 % 2.5 % 2.0 % Expected life of the option term (in years) 4.3 ​ 4.4 ​ 4.5 ​ ​ Stock option activity under the Company’s Award Plan during the year ended December 31, 2019, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted-Average ​ ​ Options ​ Exercise Price Outstanding at December 31, 2018 168,547 ​ $ 41.01 Granted 68,552 ​ $ 55.44 Cancelled and expired (37,416) ​ $ 49.11 Exercised—intrinsic value $0.8 million; cash received $1.6 million (43,017) ​ $ 38.06 Outstanding at December 31, 2019—$3.1 million intrinsic value and 7.5 years weighted-average remaining contractual term 156,666 ​ $ 46.21 Exercisable at December 31, 2019—$2.2 million intrinsic value and 6.3 years weighted-average remaining contractual term 88,377 ​ $ 41.27 Expected to vest—$2.9 million intrinsic value and 7.3 years weighted-average remaining contractual term 138,392 ​ $ 45.21 ​ ​ 8. Stock option and award plan: (Continued) A summary of the Company’s non-vested restricted stock awards as of December 31, 2019 and the changes during the year ended December 31, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Non-vested awards Shares Fair Value Non-vested at December 31, 2018 1,187,586 ​ $ 41.12 Granted 473,550 ​ $ 53.53 Vested (365,223) ​ $ 41.83 Forfeited (12,632) ​ $ 50.49 Non-vested at December 31, 2019 1,283,281 ​ $ 45.40 ​ The weighted average per share grant date fair value of restricted stock granted was $53.53 in 2019 (0.5 million shares) $44.02 in 2018 (0.5 million shares) and $40.52 in 2017 (0.5 million shares). The fair value was determined using the quoted market price of the Company’s common stock on the date of grant. Valuations were obtained to determine the fair value for the shares granted to the Company’s CEO that are subject to the total shareholder return of the Company’s common stock compared to the total shareholder return of the Nasdaq Telecommunications Index. The fair value of shares of restricted stock vested in 2019, 2018 and 2017 was $20.8 million, $19.1 million and $12.6 million, respectively. Equity-based compensation expense related to stock options and restricted stock was $18.5 million, $17.7 million, and $13.3 million for 2019, 2018, and 2017, respectively. The income tax benefit related to stock options and restricted stock was $3.0 million, $1.8 million, and $2.5 million for 2019, 2018, and 2017, respectively. The Company capitalized compensation expense related to stock options and restricted stock for 2019, 2018, and 2017 of $1.8 million, $1.7 million and $1.2 million, respectively. As of December 31, 2019, there was $31.7 million of total unrecognized compensation cost related to non-vested equity-based compensation awards. That cost is expected to be recognized over a weighted average period of 1.9 years.

Related party transactions_

Related party transactions:	12 Months Ended
	Dec. 31, 2019
Related party transactions:
Related party transactions:	9. Related party transactions: Office lease The Company’s headquarters is located in an office building owned by Sodium LLC whose owner is the Company’s Chief Executive Officer. The fixed annual rent for the headquarters building is $1.0 million per year plus an allocation of taxes and utilities. The lease began in May 2015 and the lease term was for five years . In February 2020 the lease term was extended to May 2025. The lease is cancellable by the Company upon 60 days ’ notice. The Company’s audit committee reviews and approves all transactions with related parties. The Company paid $1.7 million in 2019, $1.7 million in 2018 and $1.6 million in 2017 for rent and related costs (including taxes and utilities) for this lease.

Geographic information_

Geographic information:	12 Months Ended
	Dec. 31, 2019
Geographic information:
Geographic information:	10. Geographic information: Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing the Company’s performance. The Company has one operating segment. Revenues are attributed to regions based on where the services are provided. Below are the Company’s service revenues and long lived assets by geographic region (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 Revenues On-net ​ Off-net Non-core Total North America ​ $ 319,330 ​ $ 131,815 ​ $ 422 ​ $ 451,567 Europe ​ ​ 72,320 ​ ​ 16,323 ​ ​ 53 ​ ​ 88,696 Asia Pacific ​ 4,615 ​ ​ 778 ​ — ​ 5,393 Latin America ​ ​ 488 ​ ​ 15 ​ ​ — ​ ​ 503 Total ​ $ 396,753 ​ $ 148,931 ​ $ 475 ​ $ 546,159 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 Revenues On-net Off-net Non-core Total North America ​ $ 299,021 ​ $ 128,510 ​ $ 572 ​ $ 428,103 Europe ​ 72,958 ​ 15,918 ​ 62 ​ 88,938 Asia Pacific ​ 2,562 ​ 576 ​ — ​ 3,138 Latin America ​ ​ 14 ​ ​ — ​ ​ — ​ ​ 14 Total ​ $ 374,555 ​ $ 145,004 ​ $ 634 ​ $ 520,193 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2017 Revenues On-net Off-net Non-core Total North America ​ $ 278,714 ​ $ 122,683 ​ $ 797 ​ $ 402,194 Europe ​ 66,588 ​ 14,867 ​ 41 ​ 81,496 Asia Pacific ​ 1,143 ​ 342 ​ — ​ 1,485 Total ​ $ 346,445 ​ $ 137,892 ​ $ 838 ​ $ 485,175 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2019 2018 Long lived assets, net ​ ​ ​ ​ ​ ​ North America ​ $ 269,364 ​ $ 275,367 Europe and other ​ 99,582 ​ 99,978 Total ​ $ 368,946 ​ $ 375,345 ​

Quarterly financial information

Quarterly financial information (unaudited):	12 Months Ended
	Dec. 31, 2019
Quarterly financial information (unaudited):
Quarterly financial information (unaudited):	11. Quarterly financial information (unaudited): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2019 2019 2019 2019 ​ ​ (in thousands, except share and per share amounts) Service revenue ​ $ 134,137 ​ $ 134,789 ​ $ 136,942 ​ $ 140,292 Network operations, including equity-based compensation expense ​ 54,150 ​ 54,407 ​ 55,253 ​ 55,990 Gains on equipment transactions ​ ​ 536 ​ ​ 185 ​ ​ 87 ​ ​ 251 Operating income ​ 24,400 ​ 22,022 ​ 25,799 ​ 28,033 Net income (1) ​ 9,217 ​ 7,136 ​ 13,701 ​ 7,465 Net income per common share—basic and diluted ​ 0.20 ​ 0.16 ​ 0.30 ​ 0.16 Weighted-average number of common shares—basic ​ ​ 45,223,157 ​ ​ 45,354,327 ​ ​ 45,438,656 ​ ​ 45,553,727 Weighted-average number of common shares—diluted ​ 45,644,236 ​ 45,912,291 ​ 46,019,691 ​ 46,145,970 ​ ​ 11. Quarterly financial information (unaudited): (Continued) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2018 2018 2018 2018 ​ ​ (in thousands, except share and per share amounts) Service revenue ​ $ 128,706 ​ $ 129,296 ​ $ 130,139 ​ $ 132,049 Network operations, including equity-based compensation expense ​ 54,875 ​ 54,379 ​ 54,615 ​ 55,660 Gains on equipment transactions ​ ​ 117 ​ ​ 357 ​ ​ 416 ​ ​ 92 Operating income ​ 20,637 ​ 21,354 ​ 22,255 ​ 22,311 Net income ​ 6,784 ​ 6,552 ​ 8,231 ​ 7,100 Net income per common share—basic and diluted ​ 0.15 ​ 0.15 ​ 0.18 ​ 0.16 Weighted-average number of common shares—basic ​ ​ 44,923,973 ​ 45,016,767 ​ 45,105,830 ​ 45,284,481 Weighted-average number of common shares—diluted ​ ​ 45,294,697 ​ 45,536,473 ​ 45,699,635 ​ 45,803,418 (1) Included in net income for the three months ended September 30, 2019 and December 31, 2019 are an unrealized gain and (loss) on foreign exchange on the Company’s 2024 Notes of $6.1 million and ($4.0) million, respectively.

Subsequent Events_

Subsequent Events:	12 Months Ended
	Dec. 31, 2019
Subsequent Events:
Subsequent Events:	12. Subsequent Events: Dividend On February 26,2020, the Company’s Board of Directors approved the payment of its quarterly dividend of $0.66 per common share. The dividend for the first quarter of 2020 will be paid to holders of record on March 13,2020. This estimated $30.1 million dividend payment is expected to be made on March 27,2020.

Schedule II VALUATION AND QUALI

Schedule II VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2019
Schedule II VALUATION AND QUALIFYING ACCOUNTS
Schedule II VALUATION AND QUALIFYING ACCOUNTS	Schedule II COGENT COMMUNICATIONS HOLDINGS, INC. AND SUBSIDIARIES ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Charged to ​ ​ ​ ​ Balance at ​ ​ Beginning of ​ Costs and ​ ​ ​ ​ End of Description Period Expenses (Deductions) Period Allowance for doubtful service accounts receivable (deducted from accounts receivable)(a) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 $ 1,734 $ 4,835 $ (5,070) $ 1,499 Year ended December 31, 2018 $ 1,499 $ 4,115 $ (4,351) $ 1,263 Year ended December 31, 2019 $ 1,263 $ 6,190 $ (5,682) $ 1,771 Deferred tax valuation allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 $ 110,194 $ 20,102 $ (623) $ 129,673 Year ended December 31, 2018 $ 129,673 $ 2,138 $ (5,232) $ 126,579 Year ended December 31, 2019 $ 126,579 $ 5,785 $ (1,295) $ 131,069 (a) Bad debt expense, net of recoveries, was approximately $4.1 million for the year ended December 31, 2019, $3.3 million for the year ended December 31, 2018 and $3.7 million for the year ended December 31, 2017.

Description of the business a_2

Description of the business and summary of significant accounting policies: (Policies)	12 Months Ended
	Dec. 31, 2019
Description of the business and summary of significant accounting policies:
Principles of consolidation	The consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles and include the accounts of the Company and all of its wholly-owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of estimates	Use of estimates The preparation of consolidated financial statements in conformity with United States generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates.
Allowance for doubtful accounts	Allowance for doubtful accounts The Company establishes an allowance for doubtful accounts and other sales credit adjustments related to its trade receivables. Trade receivables are recorded at the invoiced amount and can bear interest. Allowances for sales credits are established through a reduction of revenue, while allowances for doubtful accounts are established through a charge to selling, general, and administrative expenses as bad debt expense. The Company assesses the adequacy of these reserves by evaluating factors, such as the length of time individual receivables are past due, historical collection experience, and changes in the credit worthiness of its customers. The Company also assesses the ability of specific customers to meet their financial obligations and establishes specific allowances related to these customers. If circumstances relating to specific customers change or economic conditions change such that the Company’s past collection experience and assessment of the economic environment are no longer appropriate, the Company’s estimate of the recoverability of its trade receivables could be impacted. Accounts receivable balances are written-off against the allowance for doubtful accounts after all means of internal collection activities have been exhausted and the potential for recovery is considered remote. The Company recognized bad debt expense, net of recoveries, of $4.1 million, $3.3 million and $3.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.
Recent Accounting Pronouncements-Adopted	Recent Accounting Pronouncements— Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases ​ ​ ​ ​ ​ ​ ​ Year ​ ​ ​ Ended ​ ​ ​ December 31, 2019 ​ ​ ​ ​ ​ ​ Finance lease cost amortization of right-of-use assets $ 19,823 ​ Interest expense on finance lease liabilities ​ ​ 17,709 ​ Operating lease cost ​ ​ 15,688 ​ Total lease costs ​ ​ 53,220 ​ Other lease information ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ Operating cash flows from finance leases ​ ​ (17,959) ​ Operating cash flows from operating leases ​ ​ (17,106) ​ Financing cash flows from finance leases ​ ​ (9,097) ​ Right-of-use assets obtained in exchange for new finance lease liabilities ​ ​ 14,307 ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ ​ 9,754 ​ Weighted-average remaining lease term — finance leases (in years) ​ ​ 14.3 ​ Weighted-average remaining lease term — operating leases (in years) ​ ​ 21.9 ​ Weighted average discount rate — finance leases ​ ​ 11.0 % Weighted average discount rate — operating leases ​ ​ 5.6 % Finance leases—fiber lease agreements The Company has entered into lease agreements with numerous providers of dark fiber under indefeasible-right-of use agreements (“IRUs). These IRUs typically have initial terms of 15 -20 The future minimum payments (principal and interest) under these finance leases are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 25,459 2021 ​ ​ 24,993 2022 ​ ​ 23,700 2023 ​ ​ 22,596 2024 ​ ​ 22,715 Thereafter ​ ​ 220,725 ​ ​ ​ ​ Total minimum finance lease obligations ​ ​ 340,188 Less—amounts representing interest ​ ​ (170,399) ​ ​ ​ ​ Present value of minimum finance lease obligations ​ ​ 169,789 Current maturities ​ ​ (8,154) ​ ​ ​ ​ Finance lease obligations, net of current maturities ​ $ 161,635 Operating leases The Company leases office space and certain data center facilities under operating leases. In certain cases the Company also enters into short term operating leases for dark fiber. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments under the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the reasonably certain lease term. The implicit rates within the Company’s operating leases are generally not determinable and the Company uses its incremental borrowing rate at the lease commencement date to determine the present value of its lease payments. The determination of the Company’s incremental borrowing rate requires judgment. The Company determines its incremental borrowing rate for each lease using its current borrowing rate, adjusted for various factors including level of collateralization and term to align with the term of the lease. The determination of the Company's incremental borrowing rate requires judgment. The Company determines its incremental borrowing rate for each lease using its current borrowing rate, adjusted for various factors including level of collateralization and term to align with the term of the lease. Certain of the Company’s leases include options to extend or terminate the lease. The Company establishes the number of renewal option periods used in determining the operating lease term based upon its assessment at the inception of the operating lease of the number of option periods for which failure to renew the lease imposes a penalty in such amount that renewal appears to be reasonably certain. The option to renew may be automatic, at the option of the Company or mutually agreed to between the landlord or dark fiber provider and the Company. Once the Company has accepted the related fiber route or the facility lease term has begun, the present value of the aggregate future minimum operating lease payments is recorded as an operating lease liability and a right-of-use leased asset. Lease incentives and deferred rent liabilities for facilities operating leases are presented with the right-of-use leased asset. Lease expense for lease payments is recognized on a straight-line basis over the term of the lease. The future minimum payments under these operating lease agreements are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 15,075 2021 ​ ​ 13,788 2022 ​ ​ 12,211 2023 ​ ​ 11,376 2024 ​ ​ 9,903 Thereafter ​ ​ 98,542 ​ ​ ​ ​ Total minimum operating lease obligations ​ ​ 160,895 Less—amounts representing interest ​ ​ (64,104) ​ ​ ​ ​ Present value of minimum operating lease obligations ​ ​ 96,791 Current maturities ​ ​ (10,101) ​ ​ ​ ​ Lease obligations, net of current maturities ​ $ 86,690
Revenue recognition	Revenue recognition The Company recognizes revenue under ASU No. 2014-09, Revenue from Contracts with Customers The Company’s service offerings consist of on-net and off-net telecommunications services. Fixed fees are billed monthly in advance and usage fees are billed monthly in arrears. Amounts billed are due upon receipt and contract lengths range from month to month to 60 months . The Company satisfies its performance obligations to provide services to customers over time as the services are rendered. In accordance with ASC 606, revenue is recognized when a customer obtains the promised service. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these services. The Company has adopted the practical expedient related to certain performance obligation disclosures since it has a right to consideration from its customer in an amount that corresponds directly with the value to the customer of the Company’s performance completed to date. To achieve this core principle, the Company follows the following five steps: 1) Identification of the contract, or contracts with a customer 2) Identification of the performance obligations in the contract 3) Determination of the transaction price 4) Allocation of the transaction price to the performance obligations in the contract 5) Recognition of revenue when, or as, we satisfy a performance obligation Fees billed in connection with customer installations are deferred (as deferred revenue) and recognized as noted above. To the extent a customer contract is terminated prior to its contractual end the customer is subject to termination fees. The Company vigorously seeks payment of these amounts. The Company recognizes revenue for these amounts as they are collected. Service revenue recognized from amounts in deferred revenue (contract liabilities) at the beginning of the period during the year ended December 31, 2019 was $4.4 million and during the year ended December 31, 2018 was $5.0 million. Amortization expense for contract costs was $17.3 million for the year ended December 31, 2019 and $16.8 million for the year ended December 31, 2018.
Gross receipts taxes, universal service fund and other surcharges	Gross receipts taxes, universal service fund and other surcharges Revenue recognition standards include guidance relating to taxes or surcharges assessed by a governmental authority that are directly imposed on a revenue-producing transaction between a seller and a customer and may include, but are not limited to, gross receipts taxes, excise taxes, Universal Service Fund fees and certain state regulatory fees. Such charges may be presented gross or net based upon the Company’s accounting policy election. The Company records certain excise taxes and surcharges on a gross basis and includes them in its revenues and costs of network operations. Excise taxes and surcharges billed to customers and recorded on a gross basis (as service revenue and network operations expense) were $14.9 million, $12.5 million, and $10.9 million for the years ended December 31, 2019, 2018 and 2017, respectively.
Network operations	Network operations Network operations expenses include the costs of personnel and related operating expenses associated with service delivery, network management, and customer support, network facilities costs, fiber and equipment maintenance fees, leased circuit costs, access fees paid to building owners and certain excise taxes and surcharges recorded on a gross basis. The Company estimates its accruals for any disputed leased circuit obligations based upon the nature and age of the dispute. Network operations costs are impacted by the timing and amounts of disputed circuit costs. The Company generally records these disputed amounts when billed by the vendor and reverses these amounts when the vendor credit has been received or the dispute has otherwise been resolved. The Company does not allocate depreciation and amortization expense to its network operations expense.
Foreign currency translation adjustment and comprehensive income	Foreign currency translation adjustment and comprehensive income The consolidated financial statements of the Company’s non-US operations are translated into US dollars using the period-end foreign currency exchange rates for assets and liabilities and the average foreign currency exchange rates for revenues and expenses. Gains and losses on translation of the accounts are accumulated and reported as a component of other comprehensive income in stockholders’ equity. The Company’s only components of “other comprehensive income” are currency translation adjustments for all periods presented. The Company considers the majority of its investments in its foreign subsidiaries to be long-term in nature. The Company’s foreign exchange transaction gains (losses) are included within interest income and other on the consolidated statements of comprehensive income.
Financial instruments	Financial instruments The Company considers all highly liquid investments with an original maturity of three months or less at purchase to be cash equivalents. The Company determines the appropriate classification of its investments at the time of purchase and evaluates such designation at each balance sheet date. At December 31, 2019 and December 31, 2018, the carrying amount of cash and cash equivalents, accounts receivable, prepaid and other current assets, accounts payable, and accrued expenses approximated fair value because of the short-term nature of these instruments. The Company measures its cash equivalents at amortized cost, which approximates fair value based upon quoted market prices (Level 1). Based upon recent trading prices (Level 2—market approach) at December 31, 2019 the fair value of the Company’s $189.2 million senior unsecured notes was $191.8 million , the fair value of the Company's $445.0 million senior secured notes was $466.1 million and the fair value of the Company’s €135.0 million ($151.4 million) senior unsecured notes was $155.4 million.
Concentrations of credit risk	Concentrations of credit risk The Company's assets that are exposed to credit risk consist of its cash and cash equivalents, other assets and accounts receivable. As of December 31, 2019 and 2018, the Company's cash equivalents were invested in demand deposit accounts, overnight investments and money market funds. The Company places its cash equivalents in instruments that meet high-quality credit standards as specified in the Company's investment policy guidelines. Accounts receivable are due from customers located in major metropolitan areas in the United States, Europe, Canada, Mexico, Asia, Latin America and Australia. Receivables from the Company's net-centric (wholesale) customers are generally subject to a higher degree of credit risk than the Company's corporate customers. The Company relies upon an equipment vendor for the majority of its network equipment and is also dependent upon many third-party fiber providers for providing its services to its customers.
Property and equipment	Property and equipment Property and equipment are recorded at cost and depreciated once deployed using the straight-line method over the estimated useful lives of the assets. Useful lives are determined based on historical usage with consideration given to technological changes and trends in the industry that could impact the asset utilization. System infrastructure costs include the capitalized compensation costs of employees directly involved with construction activities and costs incurred by third party contractors. Assets and liabilities under finance leases are recorded at the lesser of the present value of the aggregate future minimum lease payments or the fair value of the assets under lease. Leasehold improvements include costs associated with building improvements. The Company determines the number of renewal option periods, if any, included in the lease term for purposes of amortizing leasehold improvements and the lease term of its finance leases based upon its assessment at the inception of the lease for which the failure to renew the lease imposes a penalty on the Company in such amount that a renewal appears to be reasonably assured. Expenditures for maintenance and repairs are expensed as incurred. Depreciation and amortization periods are as follows: ​ ​ ​ ​ Type of asset Depreciation or amortization period Indefeasible rights of use (IRUs) Shorter of useful life or the IRU lease agreement; generally 15 Network equipment 3 Leasehold improvements Shorter of lease term, including reasonably assured renewal periods, or useful life Software 5 years Owned buildings 40 years Office and other equipment 3 to 7 years System infrastructure 5
Long-lived assets	Long-lived assets The Company’s long-lived assets include property and equipment. These long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Impairment is determined by comparing the carrying value of these long-lived assets to management’s probability weighted estimate of the future undiscounted cash flows expected to result from the use of the assets. In the event an impairment exists, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the asset, which would be determined by using quoted market prices or valuation techniques such as the discounted present value of expected future cash flows, appraisals, or other pricing models. In the event there are changes in the planned use of the Company’s long-term assets or the Company’s expected future undiscounted cash flows are reduced significantly, the Company’s assessment of its ability to recover the carrying value of these assets could change.
Equity-based compensation	Equity-based compensation The Company recognizes compensation expense for its share-based payments granted to its employees based on their grant date fair values with the expense being recognized on a straight-line basis over the requisite service period. The Company begins recording equity-based compensation expense related to performance awards when it is considered probable that the performance conditions will be met and for market based awards compensation cost is recognized if the service condition is satisfied even if the market condition is not satisfied. Equity-based compensation expense is recognized in the statement of operations in a manner consistent with the classification of the employee's salary and other compensation.
Income taxes	Income taxes The Company’s deferred tax assets or liabilities are computed based upon the differences between financial statement and income tax bases of assets and liabilities using the enacted marginal tax rate. Deferred income tax expenses or benefits are based upon the changes in the assets or liability from period to period. At each balance sheet date, the Company assesses the likelihood that it will be able to realize its deferred tax assets. Valuation allowances are established when management determines that it is “more likely than not” that some portion or all of the deferred tax asset may not be realized. The Company considers all available positive and negative evidence in assessing the need for a valuation allowance including its historical operating results, ongoing tax planning, and forecasts of future taxable income, on a jurisdiction by jurisdiction basis. The Company reduces its valuation allowance if the Company concludes that it is “more likely than not” that it would be able to realize its deferred tax assets. Management determines whether a tax position is more likely than not to be sustained upon examination based on the technical merits of the position. Once it is determined that a position meets this recognition threshold, the position is measured to determine the amount of benefit to be recognized in the financial statements. The Company adjusts its estimated liabilities for uncertain tax positions periodically because of ongoing examinations by, and settlements with, the various taxing authorities, as well as changes in tax laws, regulations and interpretations. The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of its income tax expense.
Basic and diluted net income per common share	Basic and diluted net income per common share Shares of restricted stock are included in the computation of basic EPS as they vest and are included in diluted EPS, to the extent they are dilutive, determined using the treasury stock method. The following details the determination of the diluted weighted average shares: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended Year Ended Year Ended ​ ​ December 31, ​ December 31, ​ December 31, ​ ​ 2019 ​ 2018 ​ 2017 Weighted average common shares—basic 45,542,315 45,280,161 44,855,263 Dilutive effect of stock options 32,222 33,134 31,534 Dilutive effect of restricted stock 505,858 467,659 297,406 Weighted average common shares—diluted 46,080,395 45,780,954 45,184,203 ​ The following details unvested shares of restricted common stock as well as the anti-dilutive effects of stock options and restricted stock awards outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, December 31, ​ ​ 2019 ​ 2018 ​ 2017 Unvested shares of restricted common stock ​ 1,283,281 ​ 1,187,586 ​ 1,112,151 Anti-dilutive options for common stock ​ 39,608 ​ 53,114 ​ 47,513 Anti-dilutive shares of restricted common stock 348 3,545 ​ 201
Recent Accounting Pronouncements-to be Adopted	Recent Accounting Pronouncements—to be Adopted In June 2016, the FASB issued ASU No. 2016-13, “ Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments.

Description of the business a_3

Description of the business and summary of significant accounting policies: (Tables)	12 Months Ended
	Dec. 31, 2019
Description of the business and summary of significant accounting policies:
Schedule of lease cost	​ ​ ​ ​ ​ ​ ​ Year ​ ​ ​ Ended ​ ​ ​ December 31, 2019 ​ ​ ​ ​ ​ ​ Finance lease cost amortization of right-of-use assets $ 19,823 ​ Interest expense on finance lease liabilities ​ ​ 17,709 ​ Operating lease cost ​ ​ 15,688 ​ Total lease costs ​ ​ 53,220 ​ Other lease information ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ Operating cash flows from finance leases ​ ​ (17,959) ​ Operating cash flows from operating leases ​ ​ (17,106) ​ Financing cash flows from finance leases ​ ​ (9,097) ​ Right-of-use assets obtained in exchange for new finance lease liabilities ​ ​ 14,307 ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ ​ 9,754 ​ Weighted-average remaining lease term — finance leases (in years) ​ ​ 14.3 ​ Weighted-average remaining lease term — operating leases (in years) ​ ​ 21.9 ​ Weighted average discount rate — finance leases ​ ​ 11.0 % Weighted average discount rate — operating leases ​ ​ 5.6 %
Schedule of future minimum payments under finance leases	The future minimum payments (principal and interest) under these finance leases are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 25,459 2021 ​ ​ 24,993 2022 ​ ​ 23,700 2023 ​ ​ 22,596 2024 ​ ​ 22,715 Thereafter ​ ​ 220,725 ​ ​ ​ ​ Total minimum finance lease obligations ​ ​ 340,188 Less—amounts representing interest ​ ​ (170,399) ​ ​ ​ ​ Present value of minimum finance lease obligations ​ ​ 169,789 Current maturities ​ ​ (8,154) ​ ​ ​ ​ Finance lease obligations, net of current maturities ​ $ 161,635
Schedule of future minimum payments under operating lease agreements	The future minimum payments under these operating lease agreements are as follows (in thousands): ​ ​ ​ ​ ​ For the Twelve Months Ending December 31, ​ ​ 2020 $ 15,075 2021 ​ ​ 13,788 2022 ​ ​ 12,211 2023 ​ ​ 11,376 2024 ​ ​ 9,903 Thereafter ​ ​ 98,542 ​ ​ ​ ​ Total minimum operating lease obligations ​ ​ 160,895 Less—amounts representing interest ​ ​ (64,104) ​ ​ ​ ​ Present value of minimum operating lease obligations ​ ​ 96,791 Current maturities ​ ​ (10,101) ​ ​ ​ ​ Lease obligations, net of current maturities ​ $ 86,690
Schedule of depreciation and amortization periods	​ ​ ​ ​ Type of asset Depreciation or amortization period Indefeasible rights of use (IRUs) Shorter of useful life or the IRU lease agreement; generally 15 Network equipment 3 Leasehold improvements Shorter of lease term, including reasonably assured renewal periods, or useful life Software 5 years Owned buildings 40 years Office and other equipment 3 to 7 years System infrastructure 5
Schedule of diluted weighted average shares	​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended Year Ended Year Ended ​ ​ December 31, ​ December 31, ​ December 31, ​ ​ 2019 ​ 2018 ​ 2017 Weighted average common shares—basic 45,542,315 45,280,161 44,855,263 Dilutive effect of stock options 32,222 33,134 31,534 Dilutive effect of restricted stock 505,858 467,659 297,406 Weighted average common shares—diluted 46,080,395 45,780,954 45,184,203 ​
Schedule of unvested and anti-dilutive shares	​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, December 31, ​ ​ 2019 ​ 2018 ​ 2017 Unvested shares of restricted common stock ​ 1,283,281 ​ 1,187,586 ​ 1,112,151 Anti-dilutive options for common stock ​ 39,608 ​ 53,114 ​ 47,513 Anti-dilutive shares of restricted common stock 348 3,545 ​ 201

Property and equipment_ (Tables

Property and equipment: (Tables)	12 Months Ended
	Dec. 31, 2019
Property and equipment:
Schedule of property and equipment	Property and equipment consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Owned assets: ​ ​ ​ ​ ​ ​ Network equipment ​ $ 566,936 ​ $ 538,761 Leasehold improvements ​ 227,388 ​ 214,495 System infrastructure ​ 134,726 ​ 124,018 Software ​ 10,035 ​ 9,963 Office and other equipment ​ 18,169 ​ 16,711 Building ​ 1,252 ​ 1,277 Land ​ 106 ​ 108 ​ ​ 958,612 ​ 905,333 Less—Accumulated depreciation and amortization ​ (790,033) ​ (736,356) ​ ​ 168,579 ​ 168,977 Assets under finance leases: ​ ​ ​ ​ ​ ​ IRUs ​ 408,170 ​ 395,170 Less—Accumulated depreciation and amortization ​ (207,820) ​ (188,822) ​ ​ 200,350 ​ 206,348 Property and equipment, net ​ $ 368,929 ​ $ 375,325

Accrued and other liabilities_

Accrued and other liabilities: (Tables)	12 Months Ended
	Dec. 31, 2019
Accrued and other liabilities:
Schedule of accrued and other current liabilities	Accrued and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2019 2018 Operating accruals ​ $ 23,695 ​ $ 24,020 Deferred revenue—current portion ​ 4,316 ​ 4,504 Payroll and benefits ​ 6,613 ​ 7,695 Taxes—non-income based ​ 6,053 ​ 4,212 Interest ​ 10,624 ​ 11,000 Total ​ $ 51,301 ​ $ 51,431

Long-term debt_ (Tables)

Long-term debt: (Tables)	12 Months Ended
	Dec. 31, 2019
Long-term debt:
Schedule of aggregate future contractual maturities of long-term debt	The aggregate future contractual maturities of long-term debt were as follows as of December 31, 2019 (in thousands): ​ ​ ​ ​ For the year ending December 31, ​ ​ 2020 ​ $ 9,413 2021 ​ 192,299 2022 ​ 445,000 2023 ​ — 2024 ​ 151,411 Thereafter ​ — Total ​ $ 798,123

Income taxes_ (Tables)

Income taxes: (Tables)	12 Months Ended
	Dec. 31, 2019
Income taxes:
Schedule of components of income before income taxes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Domestic ​ $ 72,773 ​ $ 63,878 ​ $ 52,250 Foreign ​ (20,099) ​ (22,496) ​ (21,132) Total income before income taxes ​ $ 52,674 ​ $ 41,382 ​ $ 31,118
Schedule of income tax expense	The income tax expense is comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ — ​ $ — ​ $ — State ​ (2,647) ​ (1,522) ​ (353) Foreign ​ (370) ​ (75) ​ (209) Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ (10,899) ​ (9,746) ​ (24,150) State ​ (1,285) ​ (802) ​ (430) Foreign ​ 47 ​ (570) ​ (100) Total income tax expense ​ $ (15,154) ​ $ (12,715) ​ $ (25,242)
Schedule of net deferred tax assets	Our consolidated temporary differences comprising our net deferred tax assets are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Deferred Tax Assets: ​ ​ ​ ​ ​ ​ Net operating loss carry-forwards ​ $ 255,269 ​ $ 255,235 Tax credits ​ 2,261 ​ 2,458 Equity-based compensation ​ ​ 4,116 ​ ​ 3,322 Operating leases ​ ​ 32,289 ​ ​ — Total gross deferred tax assets ​ 293,935 ​ 261,015 Valuation allowance ​ ​ (131,069) ​ ​ (126,579) ​ ​ ​ 162,866 ​ ​ 134,436 Deferred Tax Liabilities: ​ ​ ​ ​ ​ ​ Depreciation and amortization ​ 34,884 ​ 29,769 Accrued liabilities and other ​ 107,711 ​ 101,934 Right-of-use assets ​ ​ 29,670 ​ ​ — Gross deferred tax liabilities ​ 172,265 ​ 131,703 Net deferred tax (liabilities) assets ​ $ (9,399) ​ $ 2,733
Schedule of reconciliation of the Federal statutory income taxes to the amounts reported in the financial statements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2019 2018 2017 Federal income tax expense at statutory rates ​ $ (11,061) ​ $ (8,690) ​ $ (10,892) Effect of: ​ ​ ​ ​ ​ ​ ​ ​ ​ State income taxes, net of federal benefit ​ (2,973) ​ (2,665) ​ (2,244) Impact of foreign operations ​ (11) ​ (146) ​ 74 Non-deductible expenses ​ (592) ​ (1,274) ​ (1,350) Federal tax rate change ​ — ​ — ​ (9,046) Tax effect of TCJA from foreign earnings ​ (28) ​ (130) ​ (2,296) Other ​ (581) ​ (645) ​ 239 Changes in valuation allowance ​ 92 ​ 835 ​ 273 Income tax expense ​ $ (15,154) ​ $ (12,715) ​ $ (25,242)

Commitments and contingencies_

Commitments and contingencies: (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and contingencies:
Schedule of future minimum annual payments under operating leases, other facility leases and building access agreements	​ ​ ​ ​ ​ For the year ending December 31, ​ ​ 2020 ​ $ 21,044 2021 ​ 10,983 2022 ​ 5,362 2023 ​ 3,348 2024 ​ 1,511 Thereafter ​ 1,944 ​ ​ $ 44,192

Stock option and award plan_ (T

Stock option and award plan: (Tables)	12 Months Ended
	Dec. 31, 2019
Stock option and award plan:
Schedule of assumptions used for determining the fair value of options granted	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, ​ Black-Scholes Assumptions 2019 2018 2017 Dividend yield 4.5 % 4.6 % 4.1 % Expected volatility 28.3 % 28.7 % 27.1 % Risk-free interest rate 2.5 % 2.5 % 2.0 % Expected life of the option term (in years) 4.3 ​ 4.4 ​ 4.5 ​
Schedule of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted-Average ​ ​ Options ​ Exercise Price Outstanding at December 31, 2018 168,547 ​ $ 41.01 Granted 68,552 ​ $ 55.44 Cancelled and expired (37,416) ​ $ 49.11 Exercised—intrinsic value $0.8 million; cash received $1.6 million (43,017) ​ $ 38.06 Outstanding at December 31, 2019—$3.1 million intrinsic value and 7.5 years weighted-average remaining contractual term 156,666 ​ $ 46.21 Exercisable at December 31, 2019—$2.2 million intrinsic value and 6.3 years weighted-average remaining contractual term 88,377 ​ $ 41.27 Expected to vest—$2.9 million intrinsic value and 7.3 years weighted-average remaining contractual term 138,392 ​ $ 45.21
Schedule of non-vested restricted stock awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date Non-vested awards Shares Fair Value Non-vested at December 31, 2018 1,187,586 ​ $ 41.12 Granted 473,550 ​ $ 53.53 Vested (365,223) ​ $ 41.83 Forfeited (12,632) ​ $ 50.49 Non-vested at December 31, 2019 1,283,281 ​ $ 45.40

Geographic information_ (Tables

Geographic information: (Tables)	12 Months Ended
	Dec. 31, 2019
Geographic information:
Schedule of service revenue by geographic region and product class and long lived assets by geographic region	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 Revenues On-net ​ Off-net Non-core Total North America ​ $ 319,330 ​ $ 131,815 ​ $ 422 ​ $ 451,567 Europe ​ ​ 72,320 ​ ​ 16,323 ​ ​ 53 ​ ​ 88,696 Asia Pacific ​ 4,615 ​ ​ 778 ​ — ​ 5,393 Latin America ​ ​ 488 ​ ​ 15 ​ ​ — ​ ​ 503 Total ​ $ 396,753 ​ $ 148,931 ​ $ 475 ​ $ 546,159 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 Revenues On-net Off-net Non-core Total North America ​ $ 299,021 ​ $ 128,510 ​ $ 572 ​ $ 428,103 Europe ​ 72,958 ​ 15,918 ​ 62 ​ 88,938 Asia Pacific ​ 2,562 ​ 576 ​ — ​ 3,138 Latin America ​ ​ 14 ​ ​ — ​ ​ — ​ ​ 14 Total ​ $ 374,555 ​ $ 145,004 ​ $ 634 ​ $ 520,193 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2017 Revenues On-net Off-net Non-core Total North America ​ $ 278,714 ​ $ 122,683 ​ $ 797 ​ $ 402,194 Europe ​ 66,588 ​ 14,867 ​ 41 ​ 81,496 Asia Pacific ​ 1,143 ​ 342 ​ — ​ 1,485 Total ​ $ 346,445 ​ $ 137,892 ​ $ 838 ​ $ 485,175 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2019 2018 Long lived assets, net ​ ​ ​ ​ ​ ​ North America ​ $ 269,364 ​ $ 275,367 Europe and other ​ 99,582 ​ 99,978 Total ​ $ 368,946 ​ $ 375,345

Quarterly financial informati_2

Quarterly financial information (unaudited): (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly financial information (unaudited):
Schedule of quarterly financial information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2019 2019 2019 2019 ​ ​ (in thousands, except share and per share amounts) Service revenue ​ $ 134,137 ​ $ 134,789 ​ $ 136,942 ​ $ 140,292 Network operations, including equity-based compensation expense ​ 54,150 ​ 54,407 ​ 55,253 ​ 55,990 Gains on equipment transactions ​ ​ 536 ​ ​ 185 ​ ​ 87 ​ ​ 251 Operating income ​ 24,400 ​ 22,022 ​ 25,799 ​ 28,033 Net income (1) ​ 9,217 ​ 7,136 ​ 13,701 ​ 7,465 Net income per common share—basic and diluted ​ 0.20 ​ 0.16 ​ 0.30 ​ 0.16 Weighted-average number of common shares—basic ​ ​ 45,223,157 ​ ​ 45,354,327 ​ ​ 45,438,656 ​ ​ 45,553,727 Weighted-average number of common shares—diluted ​ 45,644,236 ​ 45,912,291 ​ 46,019,691 ​ 46,145,970 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2018 2018 2018 2018 ​ ​ (in thousands, except share and per share amounts) Service revenue ​ $ 128,706 ​ $ 129,296 ​ $ 130,139 ​ $ 132,049 Network operations, including equity-based compensation expense ​ 54,875 ​ 54,379 ​ 54,615 ​ 55,660 Gains on equipment transactions ​ ​ 117 ​ ​ 357 ​ ​ 416 ​ ​ 92 Operating income ​ 20,637 ​ 21,354 ​ 22,255 ​ 22,311 Net income ​ 6,784 ​ 6,552 ​ 8,231 ​ 7,100 Net income per common share—basic and diluted ​ 0.15 ​ 0.15 ​ 0.18 ​ 0.16 Weighted-average number of common shares—basic ​ ​ 44,923,973 ​ 45,016,767 ​ 45,105,830 ​ 45,284,481 Weighted-average number of common shares—diluted ​ ​ 45,294,697 ​ 45,536,473 ​ 45,699,635 ​ 45,803,418 (1) Included in net income for the three months ended September 30, 2019 and December 31, 2019 are an unrealized gain and (loss) on foreign exchange on the Company’s 2024 Notes of $6.1 million and ($4.0) million, respectively.

Description of the business a_4

Description of the business and summary of significant accounting policies: (Details)	12 Months Ended
	Dec. 31, 2019GBMB
Minimum
Speed per second of bandwidth (in megabits and gigabits) | MB	100
Maximum
Speed per second of bandwidth (in megabits and gigabits) | GB	100

Description of the business a_5

Description of the business and summary of significant accounting policies: Allowance for doubtful accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Description of the business and summary of significant accounting policies:
Bad debt expense, net of recoveries	$ 4.1	$ 3.3	$ 3.7

Description of the business a_6

Description of the business and summary of significant accounting policies: Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Recent accounting pronouncements- adopted
Accumulated deficit	$ (684,578)	$ (609,451)
Finance leases-fiber lease agreements
Additional finance lease future payments due	20,300
Cash paid for amounts included in the measurement of lease liabilities
Finance lease cost Amortization of right-of-use assets	19,823
Interest expense on finance lease liabilities	17,709
Operating lease cost	15,688
Total lease costs	53,220
Operating cash flows from finance leases	(17,959)
Operating cash flows from operating leases	(17,106)
Financing cash flows from finance leases	(9,097)	(10,286)	$ (11,201)
Right-of-use assets obtained in exchange for new finance lease liabilities	14,307
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 9,754
Weighted-average remaining lease term - finance leases (in years)	14 years 3 months 18 days
Weighted-average remaining lease term - operating leases (in years)	21 years 10 months 24 days
Weighted average discount rate - finance leases	11.00%
Weighted average discount rate - operating leases	5.60%
Future minimum payments (principal and interest) under these finance leases
2020	$ 25,459
2021	24,993
2022	23,700
2023	22,596
2024	22,715
Thereafter	220,725
Total minimum finance lease obligations	340,188
Less-amounts representing interest	(170,399)
Present value of minimum finance lease obligations	169,789
Current maturities, finance lease obligations	(8,154)	(7,074)
Finance lease obligations, net of current maturities	161,635	$ 156,706
Future minimum payments under these operating lease agreements
2020	15,075
2021	13,788
2022	12,211
2023	11,376
2024	9,903
Thereafter	98,542
Total minimum operating lease obligations	160,895
Less-amounts representing interest	(64,104)
Present value of minimum operating lease obligations	96,791
Current maturities, operating lease liabilities	(10,101)
Lease obligations, net of current maturities	86,690
ASU 2016-02
Recent accounting pronouncements- adopted
Accumulated deficit	$ 97,300
Minimum
Finance leases-fiber lease agreements
Initial terms	15 years
Maximum
Finance leases-fiber lease agreements
Initial terms	20 years

Description of the business a_7

Description of the business and summary of significant accounting policies: Revenue recognition (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Recent accounting pronouncements- adopted
Maximum contract lengths for billing due upon receipts (in months)		60 months
Capitalized Contract Cost, Net	$ 18.7	$ 18.7	$ 18.5
ASU 2014-09
Recent accounting pronouncements- adopted
Service revenue recognized	4.4	5
Amortization expense for contract costs	$ 17.3	$ 16.8

Description of the business a_8

Description of the business and summary of significant accounting policies: Gross receipts taxes, universal service fund and other surcharges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Description of the business and summary of significant accounting policies:
Excise taxes and surcharge	$ 14.9	$ 12.5	$ 10.9

Description of the business a_9

Description of the business and summary of significant accounting policies: Financial instruments (Details) - Dec. 31, 2019 € in Millions, $ in Millions	USD ($)	EUR (€)
Senior secured 2022 notes
Financial instruments
Senior notes	$ 189.2
Senior secured 2022 notes | Level 2
Financial instruments
Senior notes, fair value	191.8
Senior unsecured 2021 notes
Financial instruments
Senior notes	445
Senior unsecured 2021 notes | Level 2
Financial instruments
Senior notes, fair value	466.1
Senior unsecured 2024 notes
Financial instruments
Senior notes	151.4	€ 135
Senior unsecured 2024 notes | Level 2
Financial instruments
Senior notes, fair value	$ 155.4

Description of the business _10

Description of the business and summary of significant accounting policies: Property and equipment (Details)	12 Months Ended
	Dec. 31, 2019
IRU | Minimum
Property and equipment
Depreciation or amortization period (in years)	15 years
IRU | Maximum
Property and equipment
Depreciation or amortization period (in years)	20 years
Network equipment | Minimum
Property and equipment
Depreciation or amortization period (in years)	3 years
Network equipment | Maximum
Property and equipment
Depreciation or amortization period (in years)	8 years
Software
Property and equipment
Depreciation or amortization period (in years)	5 years
Building
Property and equipment
Depreciation or amortization period (in years)	40 years
Office and other equipment | Minimum
Property and equipment
Depreciation or amortization period (in years)	3 years
Office and other equipment | Maximum
Property and equipment
Depreciation or amortization period (in years)	7 years
System infrastructure | Minimum
Property and equipment
Depreciation or amortization period (in years)	5 years
System infrastructure | Maximum
Property and equipment
Depreciation or amortization period (in years)	10 years

Description of the business _11

Description of the business and summary of significant accounting policies: Basic and diluted net income per common share (Details) - shares	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Diluted weighted average shares
Weighted-average common shares - basic (in shares)	45,553,727	45,438,656	45,354,327	45,223,157	45,284,481	45,105,830	45,016,767	44,923,973	45,542,315	45,280,161	44,855,263
Weighted average common shares-diluted	46,145,970	46,019,691	45,912,291	45,644,236	45,803,418	45,699,635	45,536,473	45,294,697	46,080,395	45,780,954	45,184,203
Stock options
Diluted weighted average shares
Dilutive effect (options or restricted stock)									32,222	33,134	31,534
Anti-dilutive effects
Anti-dilutive (options or restricted stock)									39,608	53,114	47,513
Restricted stock
Diluted weighted average shares
Dilutive effect (options or restricted stock)									505,858	467,659	297,406
Anti-dilutive effects
Unvested shares of restricted common stock	1,283,281				1,187,586				1,283,281	1,187,586	1,112,151
Anti-dilutive (options or restricted stock)									348	3,545	201

Property and equipment_ (Detail

Property and equipment: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and equipment
Property and equipment, gross	$ 1,366,782	$ 1,300,503
Accumulated depreciation and amortization	(997,853)	(925,178)
Depreciation and amortization	80,247	81,233	$ 75,926
Property, Plant and Equipment, Net	368,929	375,325
Owned assets
Property and equipment
Property and equipment, gross	958,612	905,333
Accumulated depreciation and amortization	(790,033)	(736,356)
Property, Plant and Equipment, Net	168,579	168,977
Network equipment | Owned assets
Property and equipment
Property and equipment, gross	566,936	538,761
Leasehold improvements | Owned assets
Property and equipment
Property and equipment, gross	227,388	214,495
System infrastructure | Owned assets
Property and equipment
Property and equipment, gross	134,726	124,018
Capitalized salaries and related benefits of employees	10,700	10,500	$ 9,700
Software | Owned assets
Property and equipment
Property and equipment, gross	10,035	9,963
Office and other equipment | Owned assets
Property and equipment
Property and equipment, gross	18,169	16,711
Building | Owned assets
Property and equipment
Property and equipment, gross	1,252	1,277
Land | Owned assets
Property and equipment
Property and equipment, gross	106	108
IRU
Property and equipment
Property and equipment, gross	408,170	395,170
Accumulated depreciation and amortization	(207,820)	(188,822)
Property, Plant and Equipment, Net	$ 200,350	$ 206,348

Property and equipment_ Exchang

Property and equipment: Exchange agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and equipment
Non cash component of network equipment obtained in exchange transactions	$ 1	$ 1	$ 3.9
Exchange agreement | Level 3 | Network equipment
Property and equipment
Fair value of new equipment	$ 3.3	$ 3.2	$ 9.1

Property and equipment_ Install

Property and equipment: Installment payment agreement (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)payment	Dec. 31, 2018USD ($)
Installment payment agreement
Unamortized discount	$ 350	$ 395
Network equipment | Note obligations
Installment payment agreement
Term of debt (in months)	24 months
Number of payments first six months | payment	0
Number of equal payments | payment	18
Outstanding obligation	$ 12,500	11,200
Unamortized discount	$ 400	$ 400

Accrued and other liabilities_2

Accrued and other liabilities: (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued and other liabilities:
Operating accruals	$ 23,695	$ 24,020
Deferred revenue - current portion	4,316	4,504
Payroll and benefits	6,613	7,695
Taxes-non-income based	6,053	4,212
Interest	10,624	11,000
Total Accrued Liabilities	$ 51,301	$ 51,431

Long-term debt_ (Details)

Long-term debt: (Details) $ in Thousands, € in Millions	Jun. 25, 2019USD ($)	Aug. 31, 2018USD ($)	Dec. 31, 2016USD ($)	Feb. 28, 2015USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019EUR (€)	Jun. 25, 2019EUR (€)
Debt extinguishment, redemption and new debt issuances
Unrealized foreign currency exchange gain					$ (4,000)	$ 6,100	$ 2,273
Senior unsecured 2024 notes
Debt extinguishment, redemption and new debt issuances
Senior notes outstanding					151,400		151,400	€ 135
Face amount	$ 153,700								€ 135
Interest rate (as a percent)	4.375%								4.375%
Net proceeds	$ 152,100
Debt fair value					151,400		151,400
Unrealized foreign currency exchange gain							$ 2,300
Principal amount plus accrued and unpaid interest (as a percent)	100.00%						100.00%
Senior secured 2022 notes
Debt extinguishment, redemption and new debt issuances
Senior notes outstanding					$ 189,200		$ 189,200
Face amount		$ 70,000	$ 125,000	$ 250,000
Interest rate (as a percent)				5.375%
Net proceeds		$ 69,900	$ 124,300	$ 248,600
Premium percentage (as a percent)		101.75%	100.375%
Equity interest in foreign entities as collateral (in percent)							65.00%
Prior to June 30, 2021 | Senior unsecured 2024 notes
Debt extinguishment, redemption and new debt issuances
Premium percentage (as a percent)	35.00%
Principal amount plus accrued and unpaid interest (as a percent)	104.375%
After June 30, 2021 | Senior unsecured 2024 notes
Debt extinguishment, redemption and new debt issuances
Principal amount plus accrued and unpaid interest (as a percent)	102.188%
Prior to December 1, 2021 | Senior secured 2022 notes
Debt extinguishment, redemption and new debt issuances
Principal amount plus accrued and unpaid interest (as a percent)							100.00%
On or after December 1, 2021 | Senior secured 2022 notes
Debt extinguishment, redemption and new debt issuances
Principal amount plus accrued and unpaid interest (as a percent)							100.00%

Long-term debt_ Senior unsecure

Long-term debt: Senior unsecured notes - $189.2 million 2021 Notes (Details) € in Millions, $ in Millions	Jun. 25, 2019USD ($)	Apr. 09, 2014USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2019	Jun. 25, 2019EUR (€)
Senior unsecured 2021 notes
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount		$ 200	$ 189.2
Interest rate (as a percent)		5.625%
Net proceeds		$ 195.8
Interest expense on original debt			10.9
Interest expense on repurchased debt			10.8
Loss on extinguishment debt purchases			$ (0.2)
Percentage of principal amount at which notes will be required to be repurchased in the event of a change of control				101.00%
Senior unsecured 2021 notes | On or After April 15, 2017
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount plus accrued and unpaid interest (as a percent)				104.219%
Senior unsecured 2021 notes | 12-month period beginning on April 15, 2018
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount plus accrued and unpaid interest (as a percent)				102.813%
Senior unsecured 2021 notes | 12-month period beginning on April 15, 2019
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount plus accrued and unpaid interest (as a percent)				101.406%
Senior unsecured 2021 notes | 12-month period beginning on April 15, 2020
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount plus accrued and unpaid interest (as a percent)				100.00%
Senior unsecured 2024 notes
Senior unsecured notes- $189.2 million 2021 Notes
Principal amount	$ 153.7				€ 135
Interest rate (as a percent)	4.375%				4.375%
Net proceeds	$ 152.1
Percentage of principal amount at which notes will be required to be repurchased in the event of a change of control				101.00%
Principal amount plus accrued and unpaid interest (as a percent)	100.00%			100.00%
Minimum
Senior unsecured notes- $189.2 million 2021 Notes
Precenatge of principal amount by debt holders entitled to redeem remaining 2024 notes				90.00%

Long-term debt_ Limitations und

Long-term debt: Limitations under the Indentures (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2019EUR (€)	Jun. 25, 2019USD ($)	Jun. 25, 2019EUR (€)	Aug. 31, 2018USD ($)	Dec. 31, 2016USD ($)	Jun. 30, 2016USD ($)	Feb. 28, 2015USD ($)	Apr. 09, 2014USD ($)
Long-term debt
Consolidated leverage ratio	4.25	4.25
Amount permitted for investment payments	$ 110.3
Senior unsecured 2021 notes
Long-term debt
Senior notes outstanding	445
Principal amount							$ 189.2		$ 200
Interest rate (as a percent)									5.625%
Senior secured 2022 notes
Long-term debt
Senior notes outstanding	189.2
Principal amount					$ 70	$ 125		$ 250
Interest rate (as a percent)								5.375%
Senior unsecured 2024 notes
Long-term debt
Senior notes outstanding	$ 151.4	€ 135
Principal amount			$ 153.7	€ 135
Interest rate (as a percent)			4.375%	4.375%
Consolidated leverage ratio	6	6
Consolidated secured leverage ratio	4	4
Senior secured 2022 Notes and 2021 Notes
Long-term debt
Consolidated leverage ratio	5	5
Consolidated secured leverage ratio	3.5	3.5
Restriction on dividends and stock purchases
Long-term debt
Consolidated leverage ratio	4.25	4.25

Long-term debt_ Long-term debt

Long-term debt: Long-term debt maturities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Long-term debt:
2020	$ 9,413
2021	192,299
2022	445,000
2024	151,411
Total	$ 798,123

Income taxes (Details)

Income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income taxes:
Federal income tax at statutory rates (as a percent)		21.00%	35.00%
Reduction in the value of net deferred tax asset		$ 100	$ 9,000
Transition tax	$ 28	$ 130	2,296
Noncash income tax expense			$ 11,300

Income taxes_ Components of inc

Income taxes: Components of income before income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of income before income taxes
Domestic	$ 72,773	$ 63,878	$ 52,250
Foreign	(20,099)	(22,496)	(21,132)
Income before income taxes	$ 52,674	$ 41,382	$ 31,118

Income taxes_ Income tax expens

Income taxes: Income tax expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
State	$ (2,647)	$ (1,522)	$ (353)
Foreign	(370)	(75)	(209)
Deferred:
Federal	(10,899)	(9,746)	(24,150)
State	(1,285)	(802)	(430)
Foreign	47	(570)	(100)
Total income tax expense	$ (15,154)	$ (12,715)	$ (25,242)

Income taxes_ Temporary differe

Income taxes: Temporary differences (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets:
Net operating loss carry-forwards	$ 255,269	$ 255,235
Tax credits	2,261	2,458
Equity-based compensation	4,116	3,322
Operating leases	32,289
Total gross deferred tax assets	293,935	261,015
Deferred Tax Liabilities:
Depreciation and amortization	34,884	29,769
Accrued liabilities and other	107,711	101,934
Right-of-use assets	29,670
Total gross deferred tax liabilities	172,265	131,703
Deferred tax assets (liabilities)
Net deferred tax assets before valuation allowance	(9,399)	2,733
Valuation allowance	(131,069)	(126,579)
Net deferred tax assets	$ 162,866	$ 134,436

Income taxes_ Loss carry-forwar

Income taxes: Loss carry-forwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net operating loss carry-forwards
Net operating loss carry-forwards	$ 994,000
Transition tax	28	$ 130	$ 2,296
United States
Net operating loss carry-forwards
Net operating loss carry-forwards	97,600
Carry-forwards limited for use	38,400
Europe
Net operating loss carry-forwards
Net operating loss carry-forwards	890,100
Carry-forwards limited for use	145,500
Carry-forwards not limited for use	744,600
Mexico
Net operating loss carry-forwards
Net operating loss carry-forwards	3,300
Asian
Net operating loss carry-forwards
Net operating loss carry-forwards	1,800
Canada
Net operating loss carry-forwards
Net operating loss carry-forwards	1,000
Other than United States
Net operating loss carry-forwards
Carry-forwards not limited for use	$ 896,400

Income taxes_ Effective Income

Income taxes: Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of the Federal statutory income taxes to the amounts reported in the financial statements
Federal income tax expense at statutory rates	$ (11,061)	$ (8,690)	$ (10,892)
State income tax, net of federal benefit	(2,973)	(2,665)	(2,244)
Impact of foreign operations	(11)	(146)	74
Non-deductible expenses	(592)	(1,274)	(1,350)
Federal tax rate change			(9,046)
Transition tax on foreign earnings	(28)	(130)	(2,296)
Other	(581)	(645)	239
Change in valuation allowance	92	835	273
Total income tax expense	$ (15,154)	$ (12,715)	$ (25,242)

Commitments and contingencies_2

Commitments and contingencies: Current and potential litigation (Details) - USD ($) $ in Millions	Dec. 31, 2019	Mar. 31, 2015
Commitments and contingencies
Estimate of possible loss in excess of accrual	$ 3.1
Spain
Commitments and contingencies
Estimate of possible loss		$ 9

Commitments and contingencies_3

Commitments and contingencies: Capital leases - future minimum payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Future minimum payments under capital lease agreements
2020	$ 21,044
2021	10,983
2022	5,362
2023	3,348
2023	1,511
Thereafter	1,944
Total minimum lease obligations	44,192
Expenses related to operating lease arrangements	20,600	$ 20,800	$ 19,200
Short-term lease expense	$ 900

Commitments and contingencies_4

Commitments and contingencies: Unconditional purchase obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Unconditional purchase obligations
2020	$ 4,600
2021	600
2022	700
2023	700
2024	600
Thereafter	13,000
Unconditional purchase obligation	9,063	$ 8,283
Equipment and services
Unconditional purchase obligations
Unconditional purchase obligation	7,600
IRU
Unconditional purchase obligations
Unconditional purchase obligation	$ 20,300
Maximum period of maintenance payment (in years)	20 years

Commitments and contingencies_5

Commitments and contingencies: Defined contribution plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and contingencies:
Matching cash payments towards defined contribution plan	$ 0.8	$ 0.8	$ 0.7

Stockholders' equity_ Authorize

Stockholders' equity: Authorized shares (Details)	12 Months Ended
	Dec. 31, 2019Vote / shares$ / sharesshares	Dec. 31, 2018$ / sharesshares
Stockholders' equity:
Common stock, shares authorized | shares	75,000,000	75,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Preferred stock, authorized but unissued shares (in shares) | shares	10,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001
Voting rights per common share | Vote / shares	1

Stockholders' equity_ Common st

Stockholders' equity: Common stock buybacks (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common stock buyback program:
Common Stock, Shares Authorized	75,000,000	75,000,000
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Authorized amount for common stock repurchases	$ 50
Remaining authorized amount for common stock repurchases	$ 34.9
Repurchase of common stock (in shares)	0	147,995	46,750
Stock Buyback Amount During the Period		$ 6.6	$ 1.8

Stock option and award plan_ In

Stock option and award plan: Incentive award plan (Details)	12 Months Ended
	Dec. 31, 2019
Stock options
Incentive award plan
Vesting period	4 years
Expiration period	10 years
Exercise period of options vested, when an employee is terminated prior to full vesting	90 days
Restricted stock | Minimum
Incentive award plan
Vesting period	3 years
Restricted stock | Maximum
Incentive award plan
Vesting period	4 years

Stock option and award plan_ _2

Stock option and award plan: Incentive award plan fair value assumptions (Details) - Stock options - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Incentive award plan
Weighted-average per share grant date fair value (in dollars per share)	$ 8.92	$ 8.45	$ 7.06
Assumptions used for determining the fair value of options granted
Dividend yield (as a percent)	4.50%	4.60%	4.10%
Expected volatility (as a percent)	28.30%	28.70%	27.10%
Risk-free interest rate (as a percent)	2.50%	2.50%	2.00%
Expected life of the option term (in years)	4 years 3 months 18 days	4 years 4 months 24 days	4 years 6 months

Stock option and award plan_ _3

Stock option and award plan: Incentive award plan - activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock option activity parenthetical
Exercised - cash received		$ 1,637	$ 1,768	$ 1,222
Stock options
Stock option activity
Outstanding at the beginning of the period (in shares)		168,547
Granted (in shares)		68,552
Cancelled and expired (in shares)		(37,416)
Exercised (in shares)		(43,017)
Outstanding at the end of the period (in shares)	156,666	156,666	168,547
Exercisable at the end of the period (in shares)	88,377	88,377
Expected to vest (in shares)	138,392	138,392
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)		$ 41.01
Granted (in dollars per share)		55.44
Cancelled and expired (in dollars per share)		49.11
Exercised (in dollars per share)		38.06
Outstanding at the end of the period (in dollars per share)	$ 46.21	46.21	$ 41.01
Exercisable at the end of the period (in dollars per share)	41.27	41.27
Expected to vest (in dollars per share)	$ 45.21	$ 45.21
Stock option activity parenthetical
Exercised - intrinsic value		$ 800
Exercised - cash received		1,600
Outstanding end of period - intrinsic value	$ 3,100	3,100
Outstanding - weighted-average term	7 years 6 months
Exercisable - intrinsic value	$ 2,200	2,200
Exercisable - weighted average term	6 years 3 months 18 days
Expected to vest - intrinsic value	$ 2,900	$ 2,900
Expected to vest - weighted average term		7 years 3 months 18 days

Stock option and award plan_ No

Stock option and award plan: Non-vested restricted stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares
Granted (in shares)	500,000
Restricted stock
Number of shares
Non-vested at the beginning of the period (in shares)	1,187,586
Granted (in shares)	473,550	500,000	500,000
Vested (in shares)	(365,223)
Forfeited (in shares)	(12,632)
Non-vested at the end of the period (in shares)	1,283,281	1,187,586
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of the period (in dollars per share)	$ 41.12
Granted (in dollars per share)	53.53	$ 44.02	$ 40.52
Vested (in dollars per share)	41.83
Forfeited (in dollars per share)	50.49
Non-vested at the end of the period (in dollars per share)	$ 45.40	$ 41.12

Stock option and award plan_ _4

Stock option and award plan: Incentive award plan, additional information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Incentive Award Plan, additional information
Granted (in shares)	500,000
Equity-based compensation expense	$ 18,460	$ 17,708	$ 13,290
Income tax benefit related to stock options and restricted stock	3,000	1,800	2,500
Capitalized compensation expense	1,800	$ 1,700	$ 1,200
Total unrecognized compensation cost	$ 31,700
Weighted-average period to recognize unrecognized compensation cost	1 year 10 months 24 days
Restricted stock
Incentive Award Plan, additional information
Granted (in dollars per share)	$ 53.53	$ 44.02	$ 40.52
Granted (in shares)	473,550	500,000	500,000
Fair value of shares	$ 20,800	$ 19,100	$ 12,600

Related party transactions_ (De

Related party transactions: (Details) - CEO - Lease - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Office lease
Fixed annual rent		$ 1
Lease term (in years)	5 years
Notice period for cancellation of lease	60 days
Payment for rent and related costs (in dollars)		$ 1.7	$ 1.7	$ 1.6

Geographic information_ (Detail

Geographic information: (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Geographic information
Number of operating segments | segment									1
Revenues	$ 140,292	$ 136,942	$ 134,789	$ 134,137	$ 132,049	$ 130,139	$ 129,296	$ 128,706	$ 546,159	$ 520,193	$ 485,175
Long lived assets, net	368,946				375,345				368,946	375,345
On-net
Geographic information
Revenues									396,753	374,555	346,445
Off-net
Geographic information
Revenues									148,931	145,004	137,892
Non-core
Geographic information
Revenues									475	634	838
North America
Geographic information
Revenues									451,567	428,103	402,194
Long lived assets, net	269,364				275,367				269,364	275,367
North America | On-net
Geographic information
Revenues									319,330	299,021	278,714
North America | Off-net
Geographic information
Revenues									131,815	128,510	122,683
North America | Non-core
Geographic information
Revenues									422	572	797
Europe
Geographic information
Revenues									88,696	88,938	81,496
Europe | On-net
Geographic information
Revenues									72,320	72,958	66,588
Europe | Off-net
Geographic information
Revenues									16,323	15,918	14,867
Europe | Non-core
Geographic information
Revenues									53	62	41
Europe and other
Geographic information
Long lived assets, net	$ 99,582				$ 99,978				99,582	99,978
Asia Pacific
Geographic information
Revenues									5,393	3,138	1,485
Asia Pacific | On-net
Geographic information
Revenues									4,615	2,562	1,143
Asia Pacific | Off-net
Geographic information
Revenues									778	576	$ 342
Latin America
Geographic information
Revenues									503	14
Latin America | On-net
Geographic information
Revenues									488	$ 14
Latin America | Off-net
Geographic information
Revenues									$ 15

Quarterly financial informati_3

Quarterly financial information (unaudited): (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly financial information (unaudited):
Service revenue	$ 140,292	$ 136,942	$ 134,789	$ 134,137	$ 132,049	$ 130,139	$ 129,296	$ 128,706	$ 546,159	$ 520,193	$ 485,175
Unrealized foreign currency exchange gain	(4,000)	6,100							2,273
Network operations, including equity-based compensation expense	55,990	55,253	54,407	54,150	55,660	54,615	54,379	54,875	219,801	219,526	209,278
Gains on equipment transactions	251	87	185	536	92	416	357	117	1,059	982	3,862
Operating income	28,033	25,799	22,022	24,400	22,311	22,255	21,354	20,637	100,257	86,558	75,918
Net income (loss)	$ 7,465	$ 13,701	$ 7,136	$ 9,217	$ 7,100	$ 8,231	$ 6,552	$ 6,784	$ 37,520	$ 28,667	$ 5,876
Net income (loss) per common share-basic and diluted	$ 0.16	$ 0.30	$ 0.16	$ 0.20	$ 0.16	$ 0.18	$ 0.15	$ 0.15
Weighted-average number of common shares-basic	45,553,727	45,438,656	45,354,327	45,223,157	45,284,481	45,105,830	45,016,767	44,923,973	45,542,315	45,280,161	44,855,263
Weighted-average number of common shares-diluted	46,145,970	46,019,691	45,912,291	45,644,236	45,803,418	45,699,635	45,536,473	45,294,697	46,080,395	45,780,954	45,184,203

Subsequent Events_ (Details)

Subsequent Events: (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 27, 2020	Feb. 26, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Events:
Quarterly dividend payment approved (per share)		$ 0.66
Dividends paid	$ 30,100		$ 112,647	$ 97,887	$ 81,657

Schedule II VALUATION AND QUA_2

Schedule II VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in valuation and qualifying accounts
Bad debt expense, net of recoveries	$ 4,100	$ 3,300	$ 3,700
Allowance for doubtful service accounts receivable (deducted from accounts receivable)
Movement in valuation and qualifying accounts
Balance at Beginning of Period	1,263	1,499	1,734
Charged to Costs and Expenses	6,190	4,115	4,835
Deductions	(5,682)	(4,351)	(5,070)
Balance at End of Period	1,771	1,263	1,499
Deferred tax valuation allowance
Movement in valuation and qualifying accounts
Balance at Beginning of Period	126,579	129,673	110,194
Charged to Costs and Expenses	5,785	2,138	20,102
Deductions	(1,295)	(5,232)	(623)
Balance at End of Period	$ 131,069	$ 126,579	$ 129,673