Basic and Diluted Earnings per Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income attributable to SS&C common stockholders	$ 607.1	$ 650.2	$ 800.0
Shares attributable to SS&C:
Weighted-average common shares outstanding - used in calculation of basic EPS	248.3	254.0	255.6
Weighted-average common stock equivalents – stock options and restricted shares	6.2	8.0	11.7
Weighted-average common and common equivalent shares outstanding – used in calculation of diluted EPS	254.5	262.0	267.3
Earnings per share attributable to SS&C common stockholders- Basic	$ 2.45	$ 2.56	$ 3.13
Earnings per share attributable to SS&C common stockholders - Diluted	$ 2.39	$ 2.48	$ 2.99