Acquisitions - Schedule of Severance Expense Recognized (Detail) - DST [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	$ 31.4	$ 4.9
Total Cost of Revenues [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	22.9	0.6
Total Cost of Revenues [Member] | Software-enabled Services [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	21.7	0.6
Total Cost of Revenues [Member] | License, Maintenance and Related [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	1.2
Selling and Marketing [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	1.1	2.7
Research and Development [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	5.1	0.9
General and Administrative [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	2.3	0.7
Total Operating Expenses [Member]
Business Combination Separately Recognized Transactions [Line Items]
Total severance expense	$ 8.5	$ 4.3