Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Revenue Disaggregated by Revenue Type, Geographic Region and Customer

The nature, amount, timing, and uncertainty of our revenue and how revenue and cash flows are affected by economic factors is most appropriately depicted by revenue type, geographic region, and customer vertical.

Revenue by type for 2020, 2019, and 2018 was as follows (in thousands):

	2020		2019		2018
Revenue:
Cloud and related solutions	$	880,822	$	896,164	$	766,377
Software and services		63,239		52,364		58,101
Maintenance		46,472		48,282		50,581
Total revenue	$	990,533	$	996,810	$	875,059

We use the location of the customer as the basis of attributing revenue to geographic regions. Revenue by geographic region for 2020, 2019, and 2018, as a percentage of our total revenue, was as follows:

	2020			2019			2018
Americas (principally the U.S.)		86	%		87	%		85	%
Europe, Middle East and Africa (principally Europe)		10	%		9	%		10	%
Asia Pacific		4	%		4	%		5	%
Total revenue		100	%		100	%		100	%

We generate our revenue primarily from the global communications markets; however, we serve an expanding group of customers in markets including financial services, healthcare, media and entertainment companies, and government entities.  Revenue by customer vertical for 2020, 2019, and 2018, as a percentage of our total revenue, was as follows:

	2020			2019			2018
Broadband/Cable/Satellite		58	%		58	%		64	%
Telecommunications		19	%		19	%		21	%
Other		23	%		23	%		15	%
Total revenue		100	%		100	%		100	%

Rollforward of Unbilled Accounts Receivable

The following table rolls forward our unbilled accounts receivable from January 1, 2019 to December 31, 2020 (in thousands):

	Unbilled Receivables
Beginning Balance, January 1, 2019	$	37,227
Recognized during the period		252,445
Reclassified to receivables		(255,983	)
Other		(239	)
Ending Balance, December 31, 2019		33,450
Recognized during the period		248,574
Reclassified to receivables		(244,574	)
Other		335
Ending Balance, December 31, 2020	$	37,785

Rollforward of Deferred Revenue

The following table rolls forward our deferred revenue from January 1, 2019 to December 31, 2020 (in thousands):

	Deferred Revenue
Beginning Balance, January 1, 2019	$	(57,763	)
Revenue recognized that was included in deferred revenue at the beginning of the period		39,352
Consideration received in advance of services performed net of revenue recognized in the current period		(44,051	)
Other		(1,184	)
Ending Balance, December 31, 2019		(63,646	)
Revenue recognized that was included in deferred revenue at the beginning of the period		40,811
Consideration received in advance of services performed net of revenue recognized in the current period		(46,719	)
Other		(78	)
Ending Balance, December 31, 2020	$	(69,632	)

Fair Value Measurements

The following table represents the fair value hierarchy based upon three levels of inputs, of which Levels 1 and 2 are considered observable and Level 3 is unobservable, for our financial assets measured at fair value (in thousands):

	December 31, 2020						December 31, 2019
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	33,535	$	—	$	33,535	$	4,847	$	—	$	4,847
Commercial paper		—		15,746		15,746		—		26,964		26,964
Corporate debt securities		—		1,351		1,351		—		—		—
Short-term investments:
Corporate debt securities		—		38,672		38,672		—		22,159		22,159
U.S. government agency bonds		—		4,642		4,642		—		—		—
Asset-backed securities		—		8,284		8,284		—		3,950		3,950
Total	$	33,535	$	68,695	$	102,230	$	4,847	$	53,073	$	57,920

Carrying Value and Estimated Fair Value of Debt

We have chosen not to record our debt at fair value, with changes recognized in earnings each reporting period.  The following table indicates the carrying value and estimated fair value of our debt as of the indicated periods (in thousands):

	December 31, 2020				December 31, 2019
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
2018 Credit Agreement (carrying value including current maturities)	$	126,563	$	126,563	$	136,875	$	136,875
2016 Convertible debt (par value)		230,000		244,663		230,000		262,775

Allowance for Doubtful Accounts Receivable

The activity in our allowance for doubtful accounts receivable is as follows (in thousands):

	2020			2019			2018
Balance, beginning of year	$	3,735		$	3,115		$	4,149
Additions to expense		1,481			778			462
Write-offs		(1,532	)		(158	)		(1,659	)
Recoveries		—			—			—
Other		(56	)		—			163
Balance, end of year	$	3,628		$	3,735		$	3,115

Reconciliation of the Basic and Diluted EPS denominators

The reconciliation of the basic and diluted EPS denominators related to the common shares is included in the following table (in thousands):

	2020		2019		2018
Basic weighted-average common shares		32,010		32,051		32,488
Dilutive effect of restricted common stock		268		282	218
Dilutive effect of Stock Warrants		—		132	149
Diluted weighted-average common shares		32,278		32,465		32,855