Significant Accounting Policies Update (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues: Software	$ 18,845	$ 15,584
Operating expenses: Selling and marketing	6,490	5,922
Foreign Currency Translation Adjustments	(256)	4
Current assets: Accounts receivable, net	37,068
Current assets: Prepaid expenses and other	7,789		$ 5,752
Current liabilities: Deferred revenue	30,590		31,414
Non-current liabilities: Deferred revenue	964		1,063
Stockholder equity: Accumulated other comprehensive loss	(1,508)		(1,088)
Stockholder equity: Retained earnings	194,527		191,796
ASC 605 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues: Software	18,188	15,584
Operating expenses: Selling and marketing	6,029	5,922
Foreign Currency Translation Adjustments	(164)	$ 4
Current assets: Accounts receivable, net	33,681		32,279
Current assets: Prepaid expenses and other	7,553		5,752
Current liabilities: Deferred revenue	33,233		31,414
Non-current liabilities: Deferred revenue	1,080		1,063
Stockholder equity: Accumulated other comprehensive loss	(1,296)		(1,088)
Stockholder equity: Retained earnings	$ 187,933		$ 191,796