Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Preferred stock
Preferred stock, shares authorized	10,000,000				10,000,000				10,000,000		10,000,000
Computation of basic and diluted earnings per share
Net income attributable to DST Systems, Inc.									$ 352.6		$ 324.0		$ 183.1
Weighted average common shares outstanding	42,100,000	42,900,000	43,700,000	44,300,000	45,000,000	45,100,000	45,000,000	44,500,000	43,200,000		44,900,000		45,700,000
Incremental shares from restricted stock units, stock options and convertible debentures									900,000		900,000		600,000
Weighted average diluted shares outstanding	42,600,000	43,500,000	44,500,000	45,600,000	46,100,000	46,000,000	45,700,000	45,200,000	44,100,000		45,800,000		46,300,000
Basic earnings per share (in dollars per share)	$ 2.00	$ 2.26	$ 1.80	$ 2.10	$ 0.84	$ 1.90	$ 3.22	$ 1.24	$ 8.15	[1]	$ 7.22	[2]	$ 4.01
Diluted earnings per share (in dollars per share)	$ 1.97	$ 2.23	$ 1.77	$ 2.04	$ 0.82	$ 1.87	$ 3.17	$ 1.22	$ 8.00	[1]	$ 7.08	[2]	$ 3.95
Shares outstanding	41,800,000				44,300,000				41,800,000		44,300,000
Shares from options to purchase common stock, excluded from diluted earnings per share calculation									0		600,000
Incremental shares from conversion spread on Series C debentures, when dilutive									200,000		100,000
Series A Preferred Stock
Preferred stock
Preferred stock, shares authorized	100,000								100,000
Fraction of newly issued share of Series A Preferred Stock (or in some cases, shares of the Company's common stock, other securities, cash or other assets) that could be purchased, for each Right									0.001
Purchase price (in dollars per share)	225								225

[1] Earnings per share are computed independently for each of the quarters presented. Accordingly, the accumulation of 2013 quarterly earnings per share may not equal the total computed for the year.

[2] Earnings per share are computed independently for each of the quarters presented. Accordingly, the accumulation of 2012 quarterly earnings per share may not equal the total computed for the year.