Earnings per Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income attributable to SS&C common stockholders	$ 157.6	$ 126.0
Shares attributable to SS&C:
Weighted-average common shares outstanding – used in calculation of basic EPS	247.0	250.4
Weighted-average common stock equivalents – stock options and restricted shares	6.3	6.6
Weighted-average common and common equivalent shares outstanding – used in calculation of diluted EPS	253.3	257.0
Earnings per share attributable to SS&C common stockholders - Basic	$ 0.64	$ 0.5
Earnings per share attributable to SS&C common stockholders - Diluted	$ 0.62	$ 0.49