Summary of Significant Accounting Policies - Prior Period Adjustment (Details) - USD ($) $ 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
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales	$ 104,141	$ 90,516	$ 93,491	$ 93,617	$ 112,844	$ 99,705	$ 98,244	$ 92,834	$ 381,765	$ 403,627	$ 360,917
Cost of Sales									183,633	182,074	162,235
OPERATING EXPENSES
Selling, general and administrative									177,378	169,717	152,299
Selling and marketing										0	0
General and administrative										0	0
Depreciation and amortization										0	0
Research and development									44,175	46,082	41,061
Total operating expenses									256,766	215,799	193,360
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										403,627	360,917
Cost of Sales										175,282	156,280
OPERATING EXPENSES
Selling, general and administrative										0	0
Selling and marketing										116,920	103,544
General and administrative										47,652	43,807
Depreciation and amortization										18,313	16,588
Research and development										39,706	35,376
Total operating expenses										222,591	199,315
Restatement Adjustment | Depreciation and Amortization Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of Sales										6,792	5,955
OPERATING EXPENSES
Selling, general and administrative										5,145	4,948
Selling and marketing										0	0
General and administrative										0	0
Depreciation and amortization										(18,313)	(16,588)
Research and development										6,376	5,685
Total operating expenses										(6,792)	(5,955)
Restatement Adjustment | Selling, General and Administrative Adjustment
OPERATING EXPENSES
Selling, general and administrative										164,572	147,351
Selling and marketing										(116,920)	(103,544)
General and administrative										(47,652)	(43,807)
Depreciation and amortization										0	0
Research and development										0	0
Total operating expenses										0	0
Restatement Adjustment | Software Maintenance Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										0	0
Cost of Sales										0	0
Product
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales									289,679	320,584	287,248
Cost of Sales									133,246	130,876	115,761
Product | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										311,102	277,922
Cost of Sales										124,802	110,143
Product | Restatement Adjustment | Depreciation and Amortization Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of Sales										3,406	3,254
Product | Restatement Adjustment | Software Maintenance Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										9,482	9,326
Cost of Sales										2,668	2,364
Service
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales									92,086	83,043	73,669
Cost of Sales									$ 50,387	51,198	46,474
Service | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										92,525	82,995
Cost of Sales										50,480	46,137
Service | Restatement Adjustment | Depreciation and Amortization Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of Sales										3,386	2,701
Service | Restatement Adjustment | Software Maintenance Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales										(9,482)	(9,326)
Cost of Sales										$ (2,668)	$ (2,364)