Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 12,808	$ 10,943
Cost of revenue [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,606	2,004
Cost of revenue [Member] | Software delivery, Support and Maintenance [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	513	596
Cost of revenue [Member] | Client services [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,093	1,408
Selling, General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	8,325	6,132
Research and development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,877	$ 2,807