Condensed Consolidated Statement of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Operating revenues	$ 629.4	$ 373.9	$ 1,009.2	$ 735.2
Out-of-pocket reimbursements	26.8	16.6	52.5	36.0
Total revenues	656.2	390.5	1,061.7	771.2
Costs and expenses	525.2	320.4	851.6	627.3
Depreciation and amortization	34.8	24.2	58.0	46.3
Operating income	96.2	45.9	152.1	97.6
Interest expense	(6.9)	(6.5)	(12.8)	(12.6)
Other income, net	15.5	7.0	208.5	13.3
Equity in earnings of unconsolidated affiliates	3.9	10.2	23.1	16.9
Income from continuing operations before income taxes and non-controlling interest	108.7	56.6	370.9	115.2
Income taxes	35.2	22.1	53.3	42.2
Income from continuing operations before non-controlling interest	73.5	34.5	317.6	73.0
Income from discontinued operations, net of tax	1.9	18.7	4.8	37.2
Net income	75.4	53.2	322.4	110.2
Net (income) loss attributable to non-controlling interest	0.0	(0.2)	(0.6)	0.9
Net income attributable to DST Systems, Inc.	$ 75.4	$ 53.0	$ 321.8	$ 111.1
Weighted average common shares outstanding	61.9	66.6	62.5	67.1
Weighted average diluted shares outstanding	62.5	67.2	63.2	67.9
Basic earnings per share
Continuing operations attributable to DST Systems, Inc., per basic share	$ 1.19	$ 0.52	$ 5.07	$ 1.11
Discontinued operations, per basic share	0.03	0.28	0.08	0.55
Basic earnings per share	1.22	0.80	5.15	1.66
Diluted earnings per share
Continuing operations attributable to DST Systems, Inc., per diluted share	1.18	0.51	5.01	1.09
Discontinued operation, per diluted share	0.03	0.28	0.08	0.55
Diluted earnings per share	1.21	0.79	5.09	1.64
Cash dividends per share of common stock	$ 0.18	$ 0.17	$ 0.36	$ 0.33