Spok (SPOK) 10-Q 1 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 26, 2019
Document Document And Entity Information [Abstract]
Entity Registrant Name	Spok Holdings, Inc
Entity Central Index Key	0001289945
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding (shares)		19,229,112
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 47,829	$ 83,343
Short-term investments	29,854	3,963
Accounts receivable, net	38,554	32,386
Prepaid expenses and other	9,310	9,578
Inventory	1,229	1,708
Total current assets	126,776	130,978
Non-current assets:
Property and equipment, net	9,759	10,354
Operating lease right-of-use assets	16,773	0
Goodwill	133,031	133,031
Intangible assets, net	4,167	5,417
Deferred income tax assets	46,229	46,484
Other non-current assets	1,338	1,448
Total non-current assets	211,297	196,734
Total assets	338,073	327,712
Current liabilities:
Accounts payable	3,795	2,010
Accrued compensation and benefits	8,793	11,348
Accrued taxes	1,785	1,822
Deferred revenue	27,938	26,106
Operating lease liabilities	5,261	0
Other current liabilities	2,567	3,662
Total current liabilities	50,139	44,948
Non-current liabilities:
Asset retirement obligations	6,681	6,513
Operating lease liabilities	12,084	0
Other non-current liabilities	669	1,697
Total non-current liabilities	19,434	8,210
Total liabilities	69,573	53,158
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock	0	0
Common stock	2	2
Additional paid-in capital	89,415	90,559
Accumulated other comprehensive loss	(1,394)	(1,301)
Retained earnings	180,477	185,294
Total stockholders’ equity	268,500	274,554
Total liabilities and stockholders' equity	$ 338,073	$ 327,712

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Total revenue	$ 39,525	$ 40,628	$ 81,288	$ 83,742
Operating expenses:
Cost of revenue	7,239	7,596	14,831	15,495
Research and development	6,807	6,177	12,974	11,912
Technology operations	7,866	7,698	15,540	15,448
Selling and marketing	5,574	6,093	11,684	12,562
General and administrative	11,696	12,741	22,443	24,704
Depreciation, amortization and accretion	2,335	2,669	4,694	5,382
Total operating expenses	41,517	42,974	82,166	85,503
Operating loss	(1,992)	(2,346)	(878)	(1,761)
Interest income	452	342	901	625
Other income	602	102	367	54
(Loss) income before income taxes	(938)	(1,902)	390	(1,082)
Benefit from (provision for) income taxes	268	730	(318)	255
Net (loss) income	$ (670)	$ (1,172)	$ 72	$ (827)
Basic and diluted net income per common share (usd per share)	$ (0.03)	$ (0.06)	$ 0	$ (0.04)
Basic weighted average common shares outstanding (shares)	19,217,866	19,750,941	19,207,476	19,888,606
Diluted weighted average common shares outstanding (shares)	19,217,866	19,750,941	19,375,599	19,888,606
Cash dividends declared per common share (usd per share)	$ 0.125	$ 0.125	$ 0.25	$ 0.250
Wireless
Revenue:
Total revenue	$ 22,127	$ 23,658	$ 44,737	$ 47,927
Software
Revenue:
Total revenue	$ 17,398	$ 16,970	$ 36,551	$ 35,815

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (670)	$ (1,172)	$ 72	$ (827)
Other comprehensive loss, net of tax:
Foreign currency translation adjustments	(33)	(342)	(93)	(598)
Other comprehensive loss	(33)	(342)	(93)	(598)
Comprehensive loss	$ (703)	$ (1,514)	$ (21)	$ (1,425)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital & Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (shares) at Dec. 31, 2017		20,135,514
Beginning balance at Dec. 31, 2017	$ 290,529	$ 2	$ 98,731	$ 191,796
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	345			345
Purchase of common stock for tax withholding (shares)		(56,269)
Purchase of common stock for tax withholding	(892)		(892)
Amortization of stock-based compensation	1,234		1,234
Cash dividends declared	(2,589)			(2,589)
Common stock repurchase program including commissions (shares)		(127,792)
Common stock repurchase program including commissions	(1,927)		(1,927)
Issuance of restricted stock under the Equity Plan and other (shares)		4,812
Cumulative translation adjustment	(256)		(256)
Ending balance (shares) at Mar. 31, 2018		19,956,265
Ending balance at Mar. 31, 2018	291,088	$ 2	96,890	194,196
Beginning balance (shares) at Dec. 31, 2017		20,135,514
Beginning balance at Dec. 31, 2017	290,529	$ 2	98,731	191,796
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(827)
Ending balance (shares) at Jun. 30, 2018		19,472,249
Ending balance at Jun. 30, 2018	280,905	$ 2	90,418	190,485
Beginning balance (shares) at Mar. 31, 2018		19,956,265
Beginning balance at Mar. 31, 2018	291,088	$ 2	96,890	194,196
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,172)			(1,172)
Amortization of stock-based compensation	1,267		1,267
Cash dividends declared	(2,539)			(2,539)
Common stock repurchase program including commissions (shares)		(501,782)
Common stock repurchase program including commissions	(7,540)		(7,540)
Issuance of restricted stock under the Equity Plan and other (shares)		17,766
Issuance of restricted stock under the Equity Plan and other	143		143
Cumulative translation adjustment	(342)		(342)
Ending balance (shares) at Jun. 30, 2018		19,472,249
Ending balance at Jun. 30, 2018	280,905	$ 2	90,418	190,485
Beginning balance (shares) at Dec. 31, 2018		19,389,066
Beginning balance at Dec. 31, 2018	274,554	$ 2	89,258	185,294
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	742			742
Purchase of common stock for tax withholding (shares)		(67,648)
Purchase of common stock for tax withholding	(1,011)		(1,011)
Amortization of stock-based compensation	528		528
Cash dividends declared	(2,479)			(2,479)
Common stock repurchase program including commissions (shares)		(131,012)
Common stock repurchase program including commissions	(1,810)		(1,810)
Issuance of restricted stock under the Equity Plan and other (shares)		13,650
Issuance of restricted stock under the Equity Plan and other	70			70
Cumulative translation adjustment	(60)		(60)
Ending balance (shares) at Mar. 31, 2019		19,204,056
Ending balance at Mar. 31, 2019	270,534	$ 2	86,905	183,627
Beginning balance (shares) at Dec. 31, 2018		19,389,066
Beginning balance at Dec. 31, 2018	274,554	$ 2	89,258	185,294
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	72
Ending balance (shares) at Jun. 30, 2019		19,221,966
Ending balance at Jun. 30, 2019	268,500	$ 2	88,021	180,477
Beginning balance (shares) at Mar. 31, 2019		19,204,056
Beginning balance at Mar. 31, 2019	270,534	$ 2	86,905	183,627
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(670)			(670)
Amortization of stock-based compensation	1,029		1,029
Cash dividends declared	(2,480)			(2,480)
Issuance of restricted stock under the Equity Plan and other (shares)		17,910
Issuance of restricted stock under the Equity Plan and other	120		120
Cumulative translation adjustment	(33)		(33)
Ending balance (shares) at Jun. 30, 2019		19,221,966
Ending balance at Jun. 30, 2019	$ 268,500	$ 2	$ 88,021	$ 180,477

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows provided by operating activities:
Net income (loss)	$ 72	$ (827)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and accretion	4,694	5,382
Deferred income tax expense	208	(472)
Stock-based compensation	1,557	2,501
Provision for doubtful accounts, service credits and other	272	1,016
Adjustment of non-cash transaction taxes	0	(104)
Changes in assets and liabilities:
Accounts receivable	(6,682)	(2,986)
Prepaid expenses, inventory, and other assets	2,075	(309)
Accounts payable, accrued liabilities and other	(3,161)	(3,184)
Deferred revenue	1,734	4,981
Net cash provided by operating activities	769	5,998
Cash flows used in investing activities:
Purchase of property and equipment	(2,783)	(3,464)
Purchase of short-term investments	(29,650)	(3,911)
Maturity of short-term investments	4,000	4,000
Net cash used in investing activities	(28,433)	(3,375)
Cash flows used in financing activities:
Cash distributions to stockholders	(5,049)	(5,201)
Purchase of common stock (including commissions)	(1,810)	(9,467)
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	119	143
Purchase of common stock for tax withholding on vested equity awards	(1,017)	(894)
Net cash used in financing activities	(7,757)	(15,419)
Effect of exchange rate on cash	(93)	(598)
Net decrease in cash and cash equivalents	(35,514)	(13,394)
Cash and cash equivalents, beginning of period	83,343	103,179
Cash and cash equivalents, end of period	47,829	89,785
Supplemental disclosure:
Income taxes paid	$ 683	$ 457

Organization and Significant Ac

Organization and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Spok Holdings, Inc. (NASDAQ: SPOK) ("Spok," "we," "our" or the "Company") through its wholly-owned subsidiary Spok, Inc., is the global leader in healthcare communications. We deliver clinical information to care teams when and where it matters most to improve patient outcomes. Top hospitals rely on the Spok Care Connect platform to enhance workflows for clinicians, support administrative compliance, and provide a better experience for patients. Our customers send over 100 million messages each month through their Spok solutions. We offer a focused suite of unified clinical communications and collaboration solutions that include call center operations, clinical alerting and notifications, one-way and advanced two-way wireless messaging services, mobile communications and public safety solutions. We provide one-way and advanced two-way wireless messaging services including information services throughout the United States. These services are offered on a local, regional and nationwide basis employing digital networks. One-way messaging consists of numeric and alphanumeric messaging services. Numeric messaging services enable subscribers to receive messages that are composed entirely of numbers, such as a phone number, while alphanumeric messages may include numbers and letters, which enable subscribers to receive text messages. Two-way messaging services enable subscribers to send and receive messages to and from other wireless messaging devices, including pagers, mobile devices and personal computers. We also offer voice mail, personalized greeting, message storage and retrieval, and equipment loss and/or maintenance protection to both one-way and two-way messaging subscribers. These services are commonly referred to as wireless messaging and information services. We also develop, sell and support enterprise-wide systems for hospitals and other organizations needing to automate, centralize and standardize clinical communications and collaboration. These solutions are used for contact centers, clinical alerting and notification, mobile communications and messaging and for public safety notifications. These areas of market focus complement the market focus of our wireless services outlined above. These products and services are commonly referred to as software solutions and services. Basis of Presentation The accompanying Condensed Consolidated Financial Statements include our accounts and the accounts of our wholly-owned direct and indirect subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. Our Condensed Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and the rules and regulations of the United States Securities and Exchange Commission (the “SEC”). In management's opinion, the unaudited Condensed Consolidated Financial Statements include all adjustments and accruals that are necessary for the presentation of the results of all interim periods reported herein and all such adjustments are of a normal, recurring nature. As a result of the adoption of Accounting Standards Codification (“ASC”) 842, Leases , and our application of the modified retrospective approach using a cumulative-effect adjustment to our opening balance of retained earnings as of January 1, 2019, prior period amounts have not been restated under ASC 842. For additional details refer to Note 4 , "Significant Accounting Policies Update" and Note 6 , "Leases." Amounts shown on the Condensed Consolidated Statement of Operations within the operating expense categories of Cost of revenue; Research and development; Technology operations; Selling and marketing; and General and administrative are recorded exclusive of depreciation, amortization and accretion. The financial information included herein, other than the Condensed Consolidated Balance Sheet as of December 31, 2018 , is unaudited. The Condensed Consolidated Balance Sheet at December 31, 2018 has been derived from, but does not include all, the disclosures contained in the audited Consolidated Financial Statements as of and for the year ended December 31, 2018 . These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 (the “ 2018 Annual Report”). The Condensed Consolidated Statement of Operations for the interim periods presented are not necessarily indicative of the results that may be expected for a full year. Certain prior period amounts in the Condensed Consolidated Financial Statements have been reclassified to conform to the current period's presentation. For additional information refer to the 2018 Annual Report. Use of Estimates The preparation of these Condensed Consolidated Financial Statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures. On an on-going basis, we evaluate estimates and assumptions, including, but not limited to, those related to the impairment of long-lived assets; intangible assets subject to amortization and goodwill; accounts receivable allowances; revenue recognition; determining standalone selling price ("SSP") of performance obligations; variable consideration; depreciation expense; asset retirement obligations; and income taxes. We base our estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

Risks and Other Important Facto

Risks and Other Important Factors	6 Months Ended
	Jun. 30, 2019
Risks and Uncertainties [Abstract]
Risks and Other Important Factors	RISKS AND OTHER IMPORTANT FACTORS See “Item 1A. Risk Factors” of Part II of this Quarterly Report on Form 10-Q (“Quarterly Report”) and "Item 1A. Risk Factors" of Part I of the 2018 Annual Report, which describe key risks associated with our operations and industry.

Recent Accounting Standards

Recent Accounting Standards	6 Months Ended
	Jun. 30, 2019
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Standards	RECENT ACCOUNTING STANDARDS Recently Adopted Leases - In February 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-02, Leases . The new standard establishes a right-of-use (“ROU”) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than twelve months. Leases will be classified as either financing or operating with the classification affecting the pattern of expense recognition in the Condensed Consolidated Statement of Operations. On January 1, 2019, we adopted ASC 842 using the modified retrospective approach that resulted in a material adjustment to our balance sheet as of January 1, 2019. During the quarter ended June 30, 2019 we adjusted our opening balance to record the effect of adopting ASC 842 by approximately $0.4 million . As a result, the impact of the adoption of ASC 842 was an increase to assets and liabilities of approximately $17.8 million . Results for reporting periods beginning after January 1, 2019 are presented under ASC 842, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under ASC 840. In adoption of ASC 842 we elected to use the package of available practical expedients with the exception of hindsight. For additional details refer to Note 4 , "Significant Accounting Policies Update" and Note 6 , "Leases."

Significant Accounting Policies

Significant Accounting Policies Update	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies Update	SIGNIFICANT ACCOUNTING POLICIES UPDATE Our significant accounting policies are detailed in Note 1 “Organization and Significant Accounting Policies” of the 2018 Annual Report. Significant changes to our accounting policies as a result of adopting ASC 842 are discussed below: Leases - ASC 842 “Leases” Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. We have made an accounting policy election not to apply the recognition requirements of ASC 842 to short-term leases. Those leases which have a term of less than 12 months will have lease payments recognized, in our Condensed Consolidated Statement of Operations, on a straight-line basis over the lease term. An optional renewal or termination is not recognized as part of the lease term unless we determine that it is reasonably certain that we will exercise that option. The term reasonably certain is a high threshold for which pervasive evidence generally does not exist, and therefore, optional renewal periods are generally excluded from our ROU assets and lease liabilities until they have been exercised. Lease expense is recognized on a straight-line basis over the lease term. As most of our leases do not provide an implicit rate, we use an estimated incremental borrowing rate in determining the present value of lease payments. The Company uses a portfolio approach when determining the discount rate to be applied to its leases. Significant judgment is necessary when determining a discount rate because we must estimate the discount rate based on a number of factors and observable inputs including current market conditions, market yields, government bonds or currency LIBOR rates, credit risk, and other factors as necessary. The Company must also exercise significant judgment when determining whether an option to renew or terminate a lease should be included in the lease term. This judgment includes an assessment of all relevant economic factors such as costs relating to the termination or extension of a lease, importance of the underlying asset to the Company’s operations, and the terms and conditions of the optional periods in relation to current market rates. Where we have lease agreements which contain lease and non-lease components, we have elected to make use of the practical expedient to account for each separate lease component and associated non-lease component as a single lease component.

Revenue, Deferred Revenue And P

Revenue, Deferred Revenue And Prepaid Commissions	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue, Deferred Revenue and Prepaid Commissions	REVENUE, DEFERRED REVENUE AND PREPAID COMMISSIONS Wireless Revenue Wireless revenue consists of two primary components: Paging revenue and product and other revenue. Paging revenue consists primarily of recurring fees associated with the provision of messaging services and fees for paging devices and is net of a provision for service credits. Product and other revenue reflects system sales, the sale of devices and charges for paging devices that are not returned and are net of anticipated credits. Our core offering includes subscriptions to one-way or two-way messaging services for a periodic (monthly, quarterly, semiannual, or annual) service fee. This is generally based upon the type of service provided, the geographic area covered, the number of devices provided to the customer and the period of commitment. A subscriber to one-way messaging services may select coverage on a local, regional or nationwide basis to best meet their messaging needs. Two-way messaging is generally offered on a nationwide basis. In addition, subscribers either contract for a messaging device from us or they own a device, having purchased it either from us or from another vendor. We also sell devices to resellers who lease or resell devices to their subscribers and then sell messaging services utilizing our networks. We offer ancillary services, such as voicemail and equipment loss or maintenance protection, which increase the monthly recurring revenue we receive along with these traditional messaging services. We also offer encryption for one-way and two-way alphanumeric pagers that utilize AES-128 bit encryption, screen locking and remote wipe capabilities. With encryption enabled, these pagers can add Health Insurance Portability and Accountability Act ("HIPAA") security capabilities to the low cost, highly reliable and availability benefits of paging. (See Item 1. “Business,” in the 2018 Annual Report for more details.) Software Revenue Software revenue consists of two primary components: operations revenue and maintenance revenue. Operations revenue consists primarily of license revenues for our healthcare communications solutions, equipment revenues that facilitate the use of our software solutions, and professional services revenue related to the implementation of our solutions. Maintenance revenue is for ongoing support of our software solutions or related equipment (typically for one year). Revenue Recognition Revenues are recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Our software licenses and hardware are generally recognized at a point in time when we have transferred control to the customer. For software licenses, revenue is not recognized until the related license(s) has been made available to the customer and the customer can begin to benefit from its right to use the license(s). Our software licenses represent a right to use Spok’s IP as it exists at a point in time at which the license is granted. Many of our software licenses have significant standalone functionality due to their ability to process a transaction or perform a function or task, and we do not need to maintain those products, once provided to the customer, for value to exist. While the functionality of IP that we license may substantively change during the license period, customers are not contractually or practically required to update their license as a result of those changes. Our wireless, professional and maintenance services are generally recognized over time due to a customer's simultaneous receipt and consumption of the benefit as we perform the work. As we transfer control over time, we recognize revenue based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires significant judgment and is based on the nature of the products or services to be provided. Generally, we use the time-elapsed measure of progress for performance obligations which include wireless or maintenance services. We believe this method best depicts the simultaneous transfer and consumption of the benefit based on our performance as these services are generally considered standby services. For professional services, we leverage an input methodology based on the number of hours worked on a project versus the total expected hours necessary to complete the project. Revenues are recognized proportionally as hours are incurred. The following table presents our revenues disaggregated by revenue type: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Wireless products and services $ 22,127 $ 23,658 $ 44,737 $ 47,927 License 1,676 1,993 4,516 6,369 Services 4,835 4,363 10,040 8,433 Hardware 842 1,107 1,805 2,132 Maintenance 10,045 9,507 20,190 18,881 Total revenue $ 39,525 $ 40,628 $ 81,288 $ 83,742 The U.S. was the only country that accounted for more than 10% of the Company’s total revenue for the three and six months ended June 30, 2019 and 2018 . Revenue by geographic region consisted of the following for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Revenue United States $ 38,447 $ 39,109 $ 78,213 $ 81,044 International 1,078 1,519 3,075 2,698 Total revenue $ 39,525 $ 40,628 $ 81,288 $ 83,742 Deferred Revenues Our deferred revenues represent payments made to, or due from, customers in advance of our performance. Changes in the balance of total deferred revenue during the six months ended June 30, 2019 are as follows: (Dollars in thousands) December 31, 2018 Additions Revenue Recognized June 30, 2019 Deferred Revenue $ 26,582 $ 43,039 $ (41,683 ) $ 27,938 During the six months ended June 30, 2019 , the Company recognized $24.2 million related to amounts deferred as of December 31, 2018 . Prepaid Commissions Our prepaid commissions represent payments made to employees in advance of our performance on the related underlying contracts. These costs have been incurred directly in relation with obtaining a contract. As such, these costs are amortized over the estimated period of benefit. Changes in the balance of total prepaid commissions during the six months ended June 30, 2019 are as follows: (Dollars in thousands) December 31, 2018 Additions Commissions Recognized June 30, 2019 Prepaid Commissions $ 2,394 $ 2,408 $ (2,722 ) $ 2,080 Prepaid commissions are included within prepaid expenses and other on the Condensed Consolidated Balance Sheets and commissions expense is included within Selling and marketing on the Condensed Consolidated Statement of Operations. Remaining Performance Obligations We have elected not to disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less and for variable consideration which is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service that forms part of a single performance obligation. The remaining backlog is immaterial to our Condensed Consolidated Financial Statements.

Leases

Leases	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Leases	Leases We have operating lease arrangements for corporate offices, cellular towers, storage units and small building space. The building space is used to house infrastructure, such as transmitters, antennae and other various equipment for the Company’s wireless paging services. For leases with a term of 12 months or less, renewal terms are generally of an evergreen nature (either month-to-month or year-to-year). For leases with a term greater than 12 months, renewal terms are generally explicit and provide for one to five optional renewals consistent with the initial term. Many of our leases, with the exception of those for our corporate offices, include options to terminate the lease within one year . Variable lease payments, residual value guarantees or purchase options are not generally present in these leases. Lease costs are included in technology operations and general and administrative expenses on the Condensed Consolidated Statement of Operations. The following table presents lease costs disaggregated by type: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2019 Operating lease cost $ 1,347 $ 2,727 Short-term lease cost 2,232 4,169 Short-term lease cost - related party (1) 920 1,822 Total lease cost $ 4,499 $ 8,718 Supplemental Disclosure: Cash paid for amounts included in the measurement of lease liabilities - operating leases $ 1,375 Weighted-average remaining lease term - operating leases 5.91 years Weighted-average discount rate - operating leases 5.5 % (1) A member of our Board of Directors also serves as a director for an entity that leases transmission tower sites to the Company. Refer to Note 13 , "Related Parties" for additional details. Maturities of lease liabilities as of June 30, 2019 were as follows: For the Year Ended December 31, (Dollars in thousands) For the remaining six months ending December 31, 2019 $ 2,755 2020 4,849 2021 3,814 2022 2,309 2023 1,641 Thereafter 4,887 Total future lease payments 20,255 Imputed interest (2,910 ) Total $ 17,345

Consolidated Financial Statemen

Consolidated Financial Statement Components	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidated Financial Statement Components	CONSOLIDATED FINANCIAL STATEMENT COMPONENTS Depreciation, Amortization and Accretion Depreciation, amortization and accretion expenses consisted of the following for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Depreciation Leasehold improvements $ 12 $ 67 $ 36 $ 135 Asset retirement costs (192 ) (76 ) (384 ) (152 ) Paging and computer equipment 1,657 1,815 3,323 3,670 Furniture, fixtures and vehicles 95 103 193 209 Total depreciation 1,572 1,909 3,168 3,862 Amortization 625 625 1,250 1,250 Accretion 138 135 276 270 Total depreciation, amortization and accretion expense $ 2,335 $ 2,669 $ 4,694 $ 5,382 Accounts Receivable, Net Accounts receivable was recorded net of an allowance of $ 1.2 million and $1.7 million at June 30, 2019 and December 31, 2018 , respectively. Accounts receivable, net includes $3.6 million and $8.7 million of unbilled receivables at June 30, 2019 and December 31, 2018 , respectively. Unbilled receivables are defined as the Company's right to consideration in exchange for goods or services that we have transferred to the customer but have not yet billed for, generally as a result of contractual billing terms. The decrease in unbilled receivables was primarily due to an increase in billings for the six months ended June 30, 2019 . Property and Equipment, Net Property and equipment, net consisted of the following as of the dates stated: (Dollars in thousands) Useful Life June 30, 2019 December 31, 2018 Leasehold improvements shorter of useful life or lease term $ 3,619 $ 4,139 Asset retirement costs 1-5 2,036 2,021 Paging and computer equipment 1-5 98,452 98,401 Furniture, fixtures and vehicles 3-5 4,353 4,353 Total property and equipment 108,460 108,914 Accumulated depreciation (98,701 ) (98,560 ) Total property and equipment, net $ 9,759 $ 10,354

Intangible Assets, Net

Intangible Assets, Net	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	INTANGIBLE ASSETS, NET Intangible Assets Amortizable intangible assets at June 30, 2019 related primarily to customer relationships that resulted from our acquisition of Amcom Software, Inc. in 2011. Such intangibles are being amortized over a period of ten years . The net consolidated balance of intangible assets consisted of the following at June 30, 2019 : (Dollars in thousands) Useful Life Gross Carrying Accumulated Net Balance Customer relationships 10 $ 25,002 $ (20,835 ) $ 4,167 Estimated amortization of intangible assets for future periods was as follows: (Dollars in thousands) For the remaining six months ending December 31, 2019 $ 1,250 For the year ending December 31: 2020 2,500 2021 417 Total amortizable intangible assets $ 4,167

Asset Retirement Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2019
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS The components of the changes in the asset retirement obligation liabilities were: (Dollars in thousands) Short-Term Long-Term Total Balance at January 1, 2019 $ 34 $ 6,513 $ 6,547 Accretion 20 256 276 Amounts paid (84 ) — (84 ) Increases — 16 16 Reclassifications 104 (104 ) — Balance at June 30, 2019 $ 74 $ 6,681 $ 6,755 The short-term portion balance above is included within other current liabilities on the Condensed Consolidated Balance Sheet at June 30, 2019 . Increases and reductions other than accretion, reclassification and amounts paid primarily relate to changes in estimate of the underlying liability, specifically as it relates to updates in estimated costs to remove a transmitter and the estimated timing of removal. The cost associated with the estimated removal costs and timing refinements due to ongoing network rationalization activities is expected to accrete to a total liability of $8.1 million . The total estimated liability is based on the transmitter locations remaining after we have consolidated the number of networks we operate and assume the underlying leases continue to be renewed to that future date. Accretion expense was $0.3 million for the six months ended June 30, 2019 and 2018 . Accretion expense related solely to asset retirement obligations and was recorded based on the interest method.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS' EQUITY General Our authorized capital stock consists of 75 million shares of common stock, par value $0.0001 per share, and 25 million shares of preferred stock, par value $0.0001 per share. At June 30, 2019 and December 31, 2018 , we had no stock options outstanding. At June 30, 2019 and December 31, 2018 , there were 19,221,966 and 19,389,066 shares of common stock outstanding, respectively, and no shares of preferred stock outstanding. Dividends The following table details our cash dividends declared in 2019 . Cash dividends paid as disclosed in the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2019 and 2018 include previously declared cash dividends on shares of vested restricted common stock ("restricted stock") issued to our non-executive directors and dividends related to vested restricted stock units ("RSUs") issued to eligible employees. Cash dividends on RSUs and restricted stock have been accrued and are paid when the applicable vesting conditions are met. Accrued cash dividends on forfeited restricted stock and RSUs are also forfeited. Declaration Date Record Date Payment Date Per Share Amount Total Declared (1) (Dollars in thousands) February 27, 2019 March 15, 2019 March 29, 2019 $ 0.125 $ 2,479 April 24, 2019 May 24, 2019 June 24, 2019 0.125 2,480 Total $ 0.250 $ 4,959 (1) The total declared reflects the cash dividends declared in relation to common stock and unvested RSUs. On July 31, 2019, our Board of Directors declared a regular quarterly cash dividend of $0.125 per share of common stock with a record date of August 16, 2019, and a payment date of September 10, 2019. This cash dividend of approximately $2.4 million will be paid from available cash on hand. Common Stock Repurchase Program In August 2018, the Company's Board of Directors authorized the repurchase of up to $10.0 million of the Company's common stock through December 31, 2018 on the open market or in privately negotiated transactions. In November 2018, the Company's Board of Directors extended the repurchase authority through December 31, 2019. The following table presents information with respect to purchases made by the Company during the six months ended June 30, 2019 : Period Total Number of Shares Purchased Average Price Paid Per Share (1) Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs (Dollars in thousands) Balance at January 1, 2019 $ 6,555 Three Months Ended March 31, 2019 131,012 $ 13.77 131,012 $ 4,749 Three Months Ended June 30, 2019 — — — $ 4,749 Total 131,012 $ 13.77 131,012 (1) Average price paid per share excludes commissions of approximately $5,240 . The above table excludes shares repurchased to settle employee tax withholdings related to the vesting of equity awards. Net (Loss) Income per Common Share Basic net (loss) income per common share is computed on the basis of the weighted average common shares outstanding. Diluted net (loss) income per common share is computed on the basis of the weighted average common shares outstanding plus the effect of all potentially dilutive common shares including outstanding restricted stock and RSUs, which are treated as contingently issuable shares, using the “treasury stock” method. The components of basic and diluted net (loss) income per common share were as follows for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (in thousands, except for share and per share amounts) 2019 2018 2019 2018 Numerator: Net (loss) income $ (670 ) $ (1,172 ) $ 72 $ (827 ) Denominator: Basic weighted average outstanding shares of common stock 19,217,866 19,750,941 19,207,476 19,888,606 Diluted weighted average outstanding shares of common stock 19,217,866 19,750,941 19,375,599 19,888,606 Basic and diluted net loss per common share $ (0.03 ) $ (0.06 ) $ — $ (0.04 ) Share-Based Compensation Plans On March 23, 2012, our Board of Directors adopted the Spok Holdings, Inc. 2012 Equity Incentive Award Plan (the “2012 Equity Plan”) that was subsequently approved by our stockholders on May 16, 2012. A total of 2,194,986 shares of common stock have been reserved for issuance under this plan. Awards under the 2012 Equity Plan may be in the form of stock options, common stock, restricted stock, RSUs, performance awards, dividend equivalents, deferred stock, deferred stock units, or stock appreciation rights. Restricted stock awards generally vest one year from the date of grant. Related dividends accumulate during the vesting period and are paid at the time of vesting. Contingent RSUs generally vest over a three -year performance period upon successful completion of the performance objectives. Non-contingent RSUs generally vest in thirds, annually, over a three -year period. Dividend equivalents rights generally accompany each RSU award and those rights accumulate and vest along with the underlying RSU. The following table summarizes the activities under the 2012 Equity Plan from January 1, 2019 through June 30, 2019 : Activity Total equity securities available at January 1, 2019 904,437 RSU and restricted stock awarded to eligible employees, net of forfeitures (257,634 ) Total equity securities available at June 30, 2019 646,803 The following table details activities with respect to outstanding RSUs and restricted stock for the six months ended June 30, 2019 : Shares Weighted- Unvested at January 1, 2019 404,325 $ 17.27 Granted 354,242 13.26 Vested (14,057 ) 15.65 Forfeited (112,605 ) 15.58 Unvested at June 30, 2019 631,905 $ 15.36 Of the 631,905 unvested RSUs and restricted stock outstanding at June 30, 2019 , 367,197 RSUs include contingent performance requirements for vesting purposes. At June 30, 2019 , there was $5.1 million of unrecognized net compensation cost related to RSUs and restricted stock, which is expected to be recognized over a weighted average period of 1.8 years. Employee Stock Purchase Plan. In 2016, our Board of Directors adopted the Spok Holdings, Inc. Employee Stock Purchase Plan ("ESPP") that was subsequently approved by our stockholders on July 25, 2016. A total of 250,000 shares of common stock have been reserved for issuance under this plan. The Company's ESPP allows employees to purchase shares of common stock at a discounted rate, subject to plan limitations. Under the ESPP, eligible participants can voluntarily elect to have contributions withheld from their pay for the duration of an offering period, subject to the ESPP limits. At the end of an offering period, contributions will be used to purchase the Company's common stock at a discount to the market price based on the first or last day of the offering period, whichever is lower. Participants are required to hold common stock for a minimum period of two years from the grant date. Participants will begin earning dividends on shares after the purchase date. Each offering period will generally last for no longer than six months. Once an offering period begins, participants cannot adjust their withholding amount. If a participant chooses to withdraw, any previously withheld funds will be returned to the participant, with no stock purchased, and that participant will be eligible to participate in the ESPP at the next offering period. If the participant terminates employment with the Company during the offering period, all contributions will be returned to the employee and no stock will be purchased at a discounted rate. The Company uses the Black-Scholes model to calculate the fair value of the common stock to be purchased each offering period on their offer date. The Black-Scholes model requires the use of estimates for the expected term, the expected volatility of the underlying common stock over the expected term, the risk-free interest rate and the expected dividend payment. For the three and six months ended June 30, 2019 and 2018 , 9,876 and 11,581 shares of the Company's common stock were purchased, respectively, for a total cost of $0.1 million for each period. The following table summarizes the activities under the ESPP from January 1, 2019 through June 30, 2019 : Activity Total ESPP equity securities available at January 1, 2019 208,159 ESPP common stock purchased by eligible employees (9,876 ) Total ESPP securities available at June 30, 2019 198,283 Amounts withheld from participants will be classified an accrued compensation and benefit on the Condensed Consolidated Balance Sheets until funds are used to purchase shares. This liability amount is immaterial to the Condensed Consolidated Financial Statements. Stock-Based Compensation Expense We record all stock-based awards, which consist of RSUs, restricted stock and the option to purchase common stock under the ESPP, at fair value as of the grant date. Stock-based compensation expense is recognized based on a straight-line amortization basis over the respective service period. Forfeitures and withdrawals are accounted for as incurred. The following table reflects the items for stock-based compensation expense on the Condensed Consolidated Statement of Operations for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Performance-based RSUs $ 434 $ 526 $ 541 $ 1,030 Time-based RSUs and restricted stock 571 724 975 1,437 ESPP 24 17 41 34 Total stock-based compensation $ 1,029 $ 1,267 $ 1,557 $ 2,501

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Spok files a consolidated U.S. Federal income tax return and income tax returns in various state, local and foreign jurisdictions as required. Our quarterly tax provision, and our quarterly estimate of our annual effective tax rate, is subject to significant variation due to several factors, including variability in accurately predicting our pre-tax and taxable income and loss and the mix of jurisdictions to which they relate, changes in how we do business, changes in our stock price, foreign currency gains (losses), tax law developments (including changes in statutes, regulations, case law, and administrative practices), and relative changes of expenses or losses for which tax benefits are not recognized. Additionally, our effective tax rate can be more or less volatile based on the amount of pre-tax income or loss. For example, the impact of discrete items and non-deductible expenses on our effective tax rate is greater when our pre-tax income is lower. For 2019, the anticipated effective income tax rate is expected to continue to differ from the Federal statutory rate of 21% primarily due to the effect of state income taxes, research and development credits, permanent differences between book and taxable income and certain discrete items. At June 30, 2019 , we had total deferred income tax assets ("DTAs") of $46.2 million and no valuation allowance. This reflects a decrease of $0.3 million from the December 31, 2018 of DTAs of $46.5 million and no valuation allowance. We consider both positive and negative evidence when evaluating the recoverability of our DTAs. The assessment is required to determine whether based on all available evidence, it is more likely than not (i.e., greater than a 50% probability) that all or some portion of the DTAs will be realized in the future. During the fourth quarter of each year, we update our multi-year forecast of taxable income for our operations which assists in analyzing the recoverability of our DTAs.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES There have been no material changes during the six months ended June 30, 2019 to the commitments and contingencies previously reported in the 2018 Annual Report.

Related Parties

Related Parties	6 Months Ended
	Jun. 30, 2019
Related Party Transactions [Abstract]
Related Parties	RELATED PARTIES A member of our Board of Directors also serves as a director for an entity that leases transmission tower sites to the Company. For the three months ended June 30, 2019 and 2018 , we incurred site rent expenses of $0.9 million and for the six months ended June 30, 2019 and 2018 , we incurred site rent expenses of $1.8 million from the entity on which the individual serves as a director. Site rent expenses are included in Technology operations expenses on the Condensed Consolidated Statement of Operations.

Organization and Significant _2

Organization and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Condensed Consolidated Financial Statements include our accounts and the accounts of our wholly-owned direct and indirect subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. Our Condensed Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and the rules and regulations of the United States Securities and Exchange Commission (the “SEC”). In management's opinion, the unaudited Condensed Consolidated Financial Statements include all adjustments and accruals that are necessary for the presentation of the results of all interim periods reported herein and all such adjustments are of a normal, recurring nature. As a result of the adoption of Accounting Standards Codification (“ASC”) 842, Leases , and our application of the modified retrospective approach using a cumulative-effect adjustment to our opening balance of retained earnings as of January 1, 2019, prior period amounts have not been restated under ASC 842. For additional details refer to Note 4 , "Significant Accounting Policies Update" and Note 6 , "Leases." Amounts shown on the Condensed Consolidated Statement of Operations within the operating expense categories of Cost of revenue; Research and development; Technology operations; Selling and marketing; and General and administrative are recorded exclusive of depreciation, amortization and accretion. The financial information included herein, other than the Condensed Consolidated Balance Sheet as of December 31, 2018 , is unaudited. The Condensed Consolidated Balance Sheet at December 31, 2018 has been derived from, but does not include all, the disclosures contained in the audited Consolidated Financial Statements as of and for the year ended December 31, 2018 . These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 (the “ 2018 Annual Report”). The Condensed Consolidated Statement of Operations for the interim periods presented are not necessarily indicative of the results that may be expected for a full year. Certain prior period amounts in the Condensed Consolidated Financial Statements have been reclassified to conform to the current period's presentation. For additional information refer to the 2018 Annual Report.
Use of Estimates	Use of Estimates The preparation of these Condensed Consolidated Financial Statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures. On an on-going basis, we evaluate estimates and assumptions, including, but not limited to, those related to the impairment of long-lived assets; intangible assets subject to amortization and goodwill; accounts receivable allowances; revenue recognition; determining standalone selling price ("SSP") of performance obligations; variable consideration; depreciation expense; asset retirement obligations; and income taxes. We base our estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.
Recent Accounting Standards	RECENT ACCOUNTING STANDARDS Recently Adopted Leases - In February 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-02, Leases . The new standard establishes a right-of-use (“ROU”) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than twelve months. Leases will be classified as either financing or operating with the classification affecting the pattern of expense recognition in the Condensed Consolidated Statement of Operations. On January 1, 2019, we adopted ASC 842 using the modified retrospective approach that resulted in a material adjustment to our balance sheet as of January 1, 2019. During the quarter ended June 30, 2019 we adjusted our opening balance to record the effect of adopting ASC 842 by approximately $0.4 million . As a result, the impact of the adoption of ASC 842 was an increase to assets and liabilities of approximately $17.8 million . Results for reporting periods beginning after January 1, 2019 are presented under ASC 842, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under ASC 840. In adoption of ASC 842 we elected to use the package of available practical expedients with the exception of hindsight. For additional details refer to Note 4 , "Significant Accounting Policies Update" and Note 6 , "Leases."
Leases - ASC 842	Leases - ASC 842 “Leases” Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. We have made an accounting policy election not to apply the recognition requirements of ASC 842 to short-term leases. Those leases which have a term of less than 12 months will have lease payments recognized, in our Condensed Consolidated Statement of Operations, on a straight-line basis over the lease term. An optional renewal or termination is not recognized as part of the lease term unless we determine that it is reasonably certain that we will exercise that option. The term reasonably certain is a high threshold for which pervasive evidence generally does not exist, and therefore, optional renewal periods are generally excluded from our ROU assets and lease liabilities until they have been exercised. Lease expense is recognized on a straight-line basis over the lease term. As most of our leases do not provide an implicit rate, we use an estimated incremental borrowing rate in determining the present value of lease payments. The Company uses a portfolio approach when determining the discount rate to be applied to its leases. Significant judgment is necessary when determining a discount rate because we must estimate the discount rate based on a number of factors and observable inputs including current market conditions, market yields, government bonds or currency LIBOR rates, credit risk, and other factors as necessary. The Company must also exercise significant judgment when determining whether an option to renew or terminate a lease should be included in the lease term. This judgment includes an assessment of all relevant economic factors such as costs relating to the termination or extension of a lease, importance of the underlying asset to the Company’s operations, and the terms and conditions of the optional periods in relation to current market rates. Where we have lease agreements which contain lease and non-lease components, we have elected to make use of the practical expedient to account for each separate lease component and associated non-lease component as a single lease component.

Revenue, Deferred Revenue And_2

Revenue, Deferred Revenue And Prepaid Commissions (Tables)	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Revenue	Revenue by geographic region consisted of the following for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Revenue United States $ 38,447 $ 39,109 $ 78,213 $ 81,044 International 1,078 1,519 3,075 2,698 Total revenue $ 39,525 $ 40,628 $ 81,288 $ 83,742 The following table presents our revenues disaggregated by revenue type: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Wireless products and services $ 22,127 $ 23,658 $ 44,737 $ 47,927 License 1,676 1,993 4,516 6,369 Services 4,835 4,363 10,040 8,433 Hardware 842 1,107 1,805 2,132 Maintenance 10,045 9,507 20,190 18,881 Total revenue $ 39,525 $ 40,628 $ 81,288 $ 83,742
Schedule of Deferred Revenue	Changes in the balance of total deferred revenue during the six months ended June 30, 2019 are as follows: (Dollars in thousands) December 31, 2018 Additions Revenue Recognized June 30, 2019 Deferred Revenue $ 26,582 $ 43,039 $ (41,683 ) $ 27,938
Schedule of Deferred Commissions	Changes in the balance of total prepaid commissions during the six months ended June 30, 2019 are as follows: (Dollars in thousands) December 31, 2018 Additions Commissions Recognized June 30, 2019 Prepaid Commissions $ 2,394 $ 2,408 $ (2,722 ) $ 2,080

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Schedule of Lease Costs	The following table presents lease costs disaggregated by type: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2019 Operating lease cost $ 1,347 $ 2,727 Short-term lease cost 2,232 4,169 Short-term lease cost - related party (1) 920 1,822 Total lease cost $ 4,499 $ 8,718 Supplemental Disclosure: Cash paid for amounts included in the measurement of lease liabilities - operating leases $ 1,375 Weighted-average remaining lease term - operating leases 5.91 years Weighted-average discount rate - operating leases 5.5 % (1) A member of our Board of Directors also serves as a director for an entity that leases transmission tower sites to the Company. Refer to Note 13 , "Related Parties" for additional details.
Schedule of Maturities of Lease Liabilities	Maturities of lease liabilities as of June 30, 2019 were as follows: For the Year Ended December 31, (Dollars in thousands) For the remaining six months ending December 31, 2019 $ 2,755 2020 4,849 2021 3,814 2022 2,309 2023 1,641 Thereafter 4,887 Total future lease payments 20,255 Imputed interest (2,910 ) Total $ 17,345

Consolidated Financial Statem_2

Consolidated Financial Statement Components (Tables)	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Depreciation, Amortization and Accretion	Depreciation, amortization and accretion expenses consisted of the following for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Depreciation Leasehold improvements $ 12 $ 67 $ 36 $ 135 Asset retirement costs (192 ) (76 ) (384 ) (152 ) Paging and computer equipment 1,657 1,815 3,323 3,670 Furniture, fixtures and vehicles 95 103 193 209 Total depreciation 1,572 1,909 3,168 3,862 Amortization 625 625 1,250 1,250 Accretion 138 135 276 270 Total depreciation, amortization and accretion expense $ 2,335 $ 2,669 $ 4,694 $ 5,382
Property, Plant and Equipment	Property and equipment, net consisted of the following as of the dates stated: (Dollars in thousands) Useful Life June 30, 2019 December 31, 2018 Leasehold improvements shorter of useful life or lease term $ 3,619 $ 4,139 Asset retirement costs 1-5 2,036 2,021 Paging and computer equipment 1-5 98,452 98,401 Furniture, fixtures and vehicles 3-5 4,353 4,353 Total property and equipment 108,460 108,914 Accumulated depreciation (98,701 ) (98,560 ) Total property and equipment, net $ 9,759 $ 10,354

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Net Consolidated Balance of Amortizable Intangible Assets	The net consolidated balance of intangible assets consisted of the following at June 30, 2019 : (Dollars in thousands) Useful Life Gross Carrying Accumulated Net Balance Customer relationships 10 $ 25,002 $ (20,835 ) $ 4,167
Estimated Amortization of Intangible Assets	Estimated amortization of intangible assets for future periods was as follows: (Dollars in thousands) For the remaining six months ending December 31, 2019 $ 1,250 For the year ending December 31: 2020 2,500 2021 417 Total amortizable intangible assets $ 4,167

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2019
Asset Retirement Obligation Disclosure [Abstract]
Changes in Asset Retirement Obligation Liabilities	The components of the changes in the asset retirement obligation liabilities were: (Dollars in thousands) Short-Term Long-Term Total Balance at January 1, 2019 $ 34 $ 6,513 $ 6,547 Accretion 20 256 276 Amounts paid (84 ) — (84 ) Increases — 16 16 Reclassifications 104 (104 ) — Balance at June 30, 2019 $ 74 $ 6,681 $ 6,755

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Cash Dividends Declared	The following table details our cash dividends declared in 2019 . Cash dividends paid as disclosed in the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2019 and 2018 include previously declared cash dividends on shares of vested restricted common stock ("restricted stock") issued to our non-executive directors and dividends related to vested restricted stock units ("RSUs") issued to eligible employees. Cash dividends on RSUs and restricted stock have been accrued and are paid when the applicable vesting conditions are met. Accrued cash dividends on forfeited restricted stock and RSUs are also forfeited. Declaration Date Record Date Payment Date Per Share Amount Total Declared (1) (Dollars in thousands) February 27, 2019 March 15, 2019 March 29, 2019 $ 0.125 $ 2,479 April 24, 2019 May 24, 2019 June 24, 2019 0.125 2,480 Total $ 0.250 $ 4,959 (1) The total declared reflects the cash dividends declared in relation to common stock and unvested RSUs.
Share Repurchase Plan	The following table presents information with respect to purchases made by the Company during the six months ended June 30, 2019 : Period Total Number of Shares Purchased Average Price Paid Per Share (1) Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs (Dollars in thousands) Balance at January 1, 2019 $ 6,555 Three Months Ended March 31, 2019 131,012 $ 13.77 131,012 $ 4,749 Three Months Ended June 30, 2019 — — — $ 4,749 Total 131,012 $ 13.77 131,012 (1) Average price paid per share excludes commissions of approximately $5,240 .
Basic and Diluted Net Income Per Common Shares	The components of basic and diluted net (loss) income per common share were as follows for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (in thousands, except for share and per share amounts) 2019 2018 2019 2018 Numerator: Net (loss) income $ (670 ) $ (1,172 ) $ 72 $ (827 ) Denominator: Basic weighted average outstanding shares of common stock 19,217,866 19,750,941 19,207,476 19,888,606 Diluted weighted average outstanding shares of common stock 19,217,866 19,750,941 19,375,599 19,888,606 Basic and diluted net loss per common share $ (0.03 ) $ (0.06 ) $ — $ (0.04 )
Activities Under Equity Plan	The following table summarizes the activities under the ESPP from January 1, 2019 through June 30, 2019 : Activity Total ESPP equity securities available at January 1, 2019 208,159 ESPP common stock purchased by eligible employees (9,876 ) Total ESPP securities available at June 30, 2019 198,283 The following table summarizes the activities under the 2012 Equity Plan from January 1, 2019 through June 30, 2019 : Activity Total equity securities available at January 1, 2019 904,437 RSU and restricted stock awarded to eligible employees, net of forfeitures (257,634 ) Total equity securities available at June 30, 2019 646,803
Summary of Outstanding RSUs	The following table details activities with respect to outstanding RSUs and restricted stock for the six months ended June 30, 2019 : Shares Weighted- Unvested at January 1, 2019 404,325 $ 17.27 Granted 354,242 13.26 Vested (14,057 ) 15.65 Forfeited (112,605 ) 15.58 Unvested at June 30, 2019 631,905 $ 15.36
Stock Based Compensation Expense	The following table reflects the items for stock-based compensation expense on the Condensed Consolidated Statement of Operations for the periods stated: For the Three Months Ended June 30, For the Six Months Ended June 30, (Dollars in thousands) 2019 2018 2019 2018 Performance-based RSUs $ 434 $ 526 $ 541 $ 1,030 Time-based RSUs and restricted stock 571 724 975 1,437 ESPP 24 17 41 34 Total stock-based compensation $ 1,029 $ 1,267 $ 1,557 $ 2,501

Organization and Significant _3

Organization and Significant Accounting Policies (Details) message in Millions	6 Months Ended
	Jun. 30, 2019message
Accounting Policies [Abstract]
Monthly messages sent through company solutions (more than)	100

Recent Accounting Standards (De

Recent Accounting Standards (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to assets	$ 338,073		$ 327,712
Increase to liabilities	69,573		$ 53,158
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect of ASC 842	$ 400
Increase to assets		$ 17,800
Increase to liabilities		$ 17,800

Revenue, Deferred Revenue And_3

Revenue, Deferred Revenue And Prepaid Commissions - Additional Information and Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)revenue_component	Jun. 30, 2018USD ($)
Revenues from External Customers and Long-Lived Assets
Total revenue	$ 39,525	$ 40,628	$ 81,288	$ 83,742
Deferred revenue recognized from previous period			24,200
United States
Revenues from External Customers and Long-Lived Assets
Total revenue	38,447	39,109	78,213	81,044
International
Revenues from External Customers and Long-Lived Assets
Total revenue	1,078	1,519	3,075	2,698
Wireless products and services
Revenues from External Customers and Long-Lived Assets
Total revenue	22,127	23,658	44,737	47,927
License
Revenues from External Customers and Long-Lived Assets
Total revenue	1,676	1,993	4,516	6,369
Services
Revenues from External Customers and Long-Lived Assets
Total revenue	4,835	4,363	10,040	8,433
Hardware
Revenues from External Customers and Long-Lived Assets
Total revenue	842	1,107	$ 1,805	2,132
Maintenance
Revenues from External Customers and Long-Lived Assets
Typical duration of revenue recognition			Maintenance revenue is for ongoing support of our software solutions or related equipment (typically for one year).
Total revenue	$ 10,045	$ 9,507	$ 20,190	$ 18,881
Wireless
Revenues from External Customers and Long-Lived Assets
Revenue primary component | revenue_component			2
Software
Revenues from External Customers and Long-Lived Assets
Revenue primary component | revenue_component			2

Revenue, Deferred Revenue And_4

Revenue, Deferred Revenue And Prepaid Commissions - Deferred Revenues (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Contract With Customer, Asset And Liability
December 31, 2018	$ 26,582
Additions	1,734	$ 4,981
June 30, 2019	27,938
Accounting Standards Update 2014-09
Contract With Customer, Asset And Liability
Additions	43,039
Revenue Recognized	$ (41,683)

Revenue, Deferred Revenue And_5

Revenue, Deferred Revenue And Prepaid Commissions - Prepaid Commissions (Details) - Prepaid Commissions $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Capitalized Contract Cost
December 31, 2018	$ 2,394
Additions	2,408
Commissions Recognized	(2,722)
June 30, 2019	$ 2,080

Leases - Additional Information

Leases - Additional Information (Details)	6 Months Ended
	Jun. 30, 2019renewal
Lessee, Lease, Description [Line Items]
Termination term	1 year
Minimum
Lessee, Lease, Description [Line Items]
Number of renewal options	1
Maximum
Lessee, Lease, Description [Line Items]
Number of renewal options	5

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 1,347	$ 2,727
Short-term lease cost	2,232	4,169
Short-term lease cost - related party	920	1,822
Total lease cost	4,499	$ 8,718
Cash paid for amounts included in the measurement of lease liabilities - operating leases	$ 1,375
Weighted-average remaining lease term - operating leases	5 years 10 months 28 days	5 years 10 months 28 days
Weighted-average discount rate - operating leases	5.50%	5.50%

Leases - Lease Maturities (Deta

Leases - Lease Maturities (Details) $ in Thousands	Jun. 30, 2019USD ($)
Leases [Abstract]
For the remaining six months ending December 31, 2019	$ 2,755
2020	4,849
2021	3,814
2022	2,309
2023	1,641
Thereafter	4,887
Total future lease payments	20,255
Imputed interest	(2,910)
Total	$ 17,345

Consolidated Financial Statem_3

Consolidated Financial Statement Components - Depreciation, Amortization and Accretion (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 1,572	$ 1,909	$ 3,168	$ 3,862
Amortization	625	625	1,250	1,250
Accretion	138	135	276	270
Total depreciation, amortization and accretion expense	2,335	2,669	4,694	5,382
Leasehold improvements
Property, Plant and Equipment [Line Items]
Depreciation	12	67	36	135
Asset retirement costs
Property, Plant and Equipment [Line Items]
Depreciation	(192)	(76)	(384)	(152)
Paging and computer equipment
Property, Plant and Equipment [Line Items]
Depreciation	1,657	1,815	3,323	3,670
Furniture, fixtures and vehicles
Property, Plant and Equipment [Line Items]
Depreciation	$ 95	$ 103	$ 193	$ 209

Consolidated Financial Statem_4

Consolidated Financial Statement Components - Accounts Receivable, Net (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts receivable	$ 1.2	$ 1.7
Contract Asset
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts receivable	$ 3.6	$ 8.7

Consolidated Financial Statem_5

Consolidated Financial Statement Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 108,460	$ 108,914
Accumulated depreciation	(98,701)	(98,560)
Total property and equipment, net	9,759	10,354
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	3,619	4,139
Asset retirement costs
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,036	2,021
Asset retirement costs | Minimum
Property, Plant and Equipment [Line Items]
Useful Life	1 year
Asset retirement costs | Maximum
Property, Plant and Equipment [Line Items]
Useful Life	5 years
Paging and computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 98,452	98,401
Paging and computer equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Life	1 year
Paging and computer equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Life	5 years
Furniture, fixtures and vehicles
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 4,353	$ 4,353
Furniture, fixtures and vehicles | Minimum
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Furniture, fixtures and vehicles | Maximum
Property, Plant and Equipment [Line Items]
Useful Life	5 years

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Details)	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Useful Life (In Years)	10 years

Intangible Assets, Net - Net Co

Intangible Assets, Net - Net Consolidated Balance of Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Useful Life (In Years)	10 years
Total amortizable intangible assets	$ 4,167	$ 5,417
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life (In Years)	10 years
Gross Carrying Amount	$ 25,002
Accumulated Amortization	(20,835)
Total amortizable intangible assets	$ 4,167

Intangible Assets, Net - Estima

Intangible Assets, Net - Estimated Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
For the remaining six months ending December 31, 2019	$ 1,250
2020	2,500
2021	417
Total amortizable intangible assets	$ 4,167	$ 5,417

Asset Retirement Obligations -

Asset Retirement Obligations - Changes in Asset Retirement Obligation Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at January 1, 2019			$ 6,547
Accretion	$ 138	$ 135	276	$ 270
Amounts paid			(84)
Increases			16
Reclassifications			0
Balance at June 30, 2019	6,755		6,755
Short-Term Portion
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at January 1, 2019			34
Accretion			20
Amounts paid			(84)
Increases			0
Reclassifications			104
Balance at June 30, 2019	74		74
Long-Term Portion
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at January 1, 2019			6,513
Accretion			256
Amounts paid			0
Increases			16
Reclassifications			(104)
Balance at June 30, 2019	$ 6,681		$ 6,681

Asset Retirement Obligations _2

Asset Retirement Obligations - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Asset Retirement Obligation Disclosure [Abstract]
Estimated liability	$ 8,100		$ 8,100
Accretion	$ 138	$ 135	$ 276	$ 270

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jul. 31, 2019	Dec. 31, 2018	Aug. 31, 2018	May 16, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized (shares)	75,000,000		75,000,000
Common stock par value (usd per share)	$ 0.0001		$ 0.0001
Preferred stock authorized (shares)	25,000,000		25,000,000
Preferred stock par value (usd per share)	$ 0.0001		$ 0.0001
Options outstanding (shares)	0		0			0
Common stock outstanding (shares)	19,221,966		19,221,966			19,389,066
Preferred stock outstanding (shares)	0		0			0
Stock repurchase authority							$ 10,000,000
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend rate (usd per share)					$ 0.125
Dividends declared					$ 2,400,000
2012 Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)								2,194,986
2012 Equity Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
2012 Equity Plan | Restricted Stock and Restricted Stock Units with Contingent Performance Requirements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
2012 Equity Plan | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Performance-based RSUs | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (shares)	631,905		631,905			404,325
2011 Long Term Incentive Plan | Restricted Stock and Restricted Stock Units with Contingent Performance Requirements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (shares)	367,197		367,197
2011 Long Term Incentive Plan | Restricted Stock and Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized, share-based awards other than options	$ 5,100,000		$ 5,100,000
Weighted-average period over which cost is expected to be recognized			1 year 9 months
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)	250,000		250,000
Award required holding period			2 years
Stock purchased during period (shares)	9,876	11,581	9,876	11,581
Stock purchased during period	$ 100,000	$ 100,000	$ 100,000	$ 100,000
ESPP | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period, maximum			6 months

Stockholders' Equity - Cash Div

Stockholders' Equity - Cash Dividends Declared to Stockholders (Details) - Common Stock $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Per Share Amount (usd per share) | $ / shares	$ 0.25
Total Declared | $	$ 4,959
Installment One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Feb. 27, 2019
Record Date	Mar. 15, 2019
Payment Date	Mar. 29, 2019
Per Share Amount (usd per share) | $ / shares	$ 0.125
Total Declared | $	$ 2,479
Installment Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Apr. 24, 2019
Record Date	May 24, 2019
Payment Date	Jun. 24, 2019
Per Share Amount (usd per share) | $ / shares	$ 0.125
Total Declared | $	$ 2,480

Stockholders' Equity - Treasury

Stockholders' Equity - Treasury Stock (Details) - USD ($)	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Shares purchased during period (shares)	0	131,012	131,012
Average price paid per share (usd per share)	$ 0	$ 13.77	$ 13.77
Commissions paid to acquire shares			$ 5,240
Common Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares purchased during period (shares)	0	131,012	131,012
Treasury stock acquired during period	$ 4,749,000	$ 4,749,000		$ 6,555,000

Stockholders' Equity - Basic an

Stockholders' Equity - Basic and Diluted Net (Loss) Income Per Common Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income (loss)	$ (670)	$ 742	$ (1,172)	$ 345	$ 72	$ (827)
Denominator:
Basic weighted average outstanding shares of common stock (shares)	19,217,866		19,750,941		19,207,476	19,888,606
Diluted weighted average outstanding shares of common stock (shares)	19,217,866		19,750,941		19,375,599	19,888,606
Basic and diluted net loss per common share (usd per share)	$ (0.03)		$ (0.06)		$ 0	$ (0.04)

Stockholders' Equity - Activiti

Stockholders' Equity - Activities Under Equity Plan (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
ESPP
Share-based Compensation Arrangement By Share-based Payment Award, Shares Authorized [Roll Forward]
Shares available for grant (shares)			208,159
ESPP common stock purchased by eligible employees (shares)	(9,876)	(11,581)	(9,876)	(11,581)
Shares available for grant (shares)	198,283		198,283
Restricted stock units | 2012 Equity Plan
Share-based Compensation Arrangement By Share-based Payment Award, Shares Authorized [Roll Forward]
Shares available for grant (shares)			904,437
Shares available for grant (shares)	646,803		646,803
Eligible Employees | Restricted stock units | 2012 Equity Plan
Share-based Compensation Arrangement By Share-based Payment Award, Shares Authorized [Roll Forward]
RSU and restricted stock awarded to eligible employees, net of forfeitures (shares)			(257,634)

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Outstanding RSUs (Details) - Restricted stock units - Performance-based RSUs	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Shares
Beginning Balance (shares) | shares	404,325
Granted (shares) | shares	354,242
Vested (shares) | shares	(14,057)
Forfeited (shares) | shares	(112,605)
Ending Balance (shares) | shares	631,905
Weighted- Average Grant Date Fair Value
Beginning Balance (usd per share) | $ / shares	$ 17.27
Granted (usd per share) | $ / shares	13.26
Vested (usd per share) | $ / shares	15.65
Forfeited (usd per share) | $ / shares	15.58
Ending Balance (usd per share) | $ / shares	$ 15.36

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 1,029	$ 1,267	$ 1,557	$ 2,501
Performance-based RSUs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	434	526	541	1,030
Time-based RSUs and restricted stock
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	571	724	975	1,437
ESPP
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 24	$ 17	$ 41	$ 34

Income Taxes (Details)

Income Taxes (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred income tax assets	$ 46,229,000	$ 46,484,000
Valuation allowance	0	$ 0
Decrease in deferred tax assets	$ (300,000)

Related Parties (Details)

Related Parties (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Director
Related Party Transaction [Line Items]
Site rent expense	$ 0.9	$ 0.9	$ 1.8	$ 1.8

Uncategorized Items - spok-2019

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 4,644,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 4,644,000