Condensed Consolidated Statement of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2015		68.6
Balance at Dec. 31, 2015	$ 1,046.0	$ 0.8	$ 136.4	$ 1,996.6	$ (1,129.7)	$ 41.9
Comprehensive income:
Net income attributable to DST Systems, Inc.	111.1			111.1
Other comprehensive loss	(45.4)					(45.4)
Dividends	(22.1)		(0.6)	(22.7)
Amortization of share based compensation	15.3		15.3
Issuance of common stock (in shares)		0.5
Issuance of common stock	(6.1)		(20.8)		(26.9)
Repurchase of common stock (in shares)		(2.7)
Repurchase of common stock	(163.9)				(163.9)
Balance (in shares) at Jun. 30, 2016		66.4
Balance at Jun. 30, 2016	947.1	$ 0.8	131.5	2,085.0	(1,266.7)	(3.5)
Balance (in shares) at Dec. 31, 2016		64.0
Balance at Dec. 31, 2016	1,115.2	$ 0.8	129.2	2,379.2	(1,410.6)	16.6
Comprehensive income:
Net income attributable to DST Systems, Inc.	321.8			321.8
Other comprehensive loss	(40.6)					(40.6)
Dividends	(22.1)		(0.7)	(22.8)
Amortization of share based compensation	13.8		13.8
Issuance of common stock (in shares)		0.3
Issuance of common stock	(2.3)		(19.3)		(21.6)
Repurchase of common stock (in shares)		(2.6)
Repurchase of common stock	(163.9)				(163.9)
Distribution of treasury stock for stock split	0.0	$ (0.2)	(40.5)	(1,297.2)	1,337.9
Balance (in shares) at Jun. 30, 2017		61.7
Balance at Jun. 30, 2017	$ 1,226.5	$ 0.6	$ 83.9	$ 1,381.0	$ (215.0)	$ (24.0)