Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Equity [Abstract]
Income from continuing operations attributable to DST Systems, Inc.	$ 34.3	$ 95.5	$ 73.9	$ 188.6
Income from discontinued operations, net of tax	18.7	12.0	37.2	26.7
Net income attributable to DST Systems, Inc.	$ 53.0	$ 107.5	$ 111.1	$ 215.3
Weighted average common shares outstanding	33.3	36.6	33.6	36.9
Incremental shares from restricted stock units and stock options	0.3	0.4	0.3	0.4
Weighted average diluted shares outstanding	33.6	37.0	33.9	37.3
Continuing operations attributable to DST Systems, Inc., per basic share	$ 1.03	$ 2.61	$ 2.20	$ 5.11
Discontinued operations, per basic share	0.56	0.33	1.11	0.73
Basic earnings per share	1.59	2.94	3.31	5.84
Continuing operations attributable to DST Systems, Inc., per diluted share	1.03	2.58	2.18	5.06
Discontinued operation, per diluted share	0.55	0.33	1.10	0.72
Diluted earnings per share	$ 1.58	$ 2.91	$ 3.28	$ 5.78
Shares outstanding	33.2	36.4	33.2	36.4
Anti-dilutive securities excluded from diluted earnings per share (in shares)	0.0	0.0	0.0	0.0