Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	$ 41,694	$ 44,152	$ 36,627
Cost of revenue [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	7,481	8,721	8,732
Cost of revenue [Member] | Software delivery, Support and Maintenance [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	2,944	4,228	4,224
Cost of revenue [Member] | Client services [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	4,537	4,493	4,508
Selling, General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	25,547	27,256	20,069
Research and development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	$ 8,666	$ 8,175	$ 7,826