Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013 affiliate	Dec. 31, 2012 affiliate
One of DST's unconsolidated affiliates
Fair value measurements
Number of unconsolidated affiliates with an interest rate swap	1	1
Interest rate swap liability	$ 54.6	$ 73.5
Fair value measured on a recurring basis | Estimated Fair Value
Fair value measurements
Deferred compensation liabilities	(51.8)	(43.8)
Derivative instruments	(1.0)	(2.3)
Total	745.3	671.9
Fair value measured on a recurring basis | Estimated Fair Value | Equity securities
Fair value measurements
Investments	751.1	651.7
Fair value measured on a recurring basis | Estimated Fair Value | Investments in pooled funds
Fair value measurements
Investments	41.2	47.9
Fair value measured on a recurring basis | Estimated Fair Value | Fixed income securities
Fair value measurements
Investments	5.8	18.4
Fair value measured on a recurring basis | Quoted prices in Active Markets for Identical Assets (Level 1)
Fair value measurements
Deferred compensation liabilities	(51.8)	(43.8)
Total	699.3	607.9
Fair value measured on a recurring basis | Quoted prices in Active Markets for Identical Assets (Level 1) | Equity securities
Fair value measurements
Investments	751.1	651.7
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2)
Fair value measurements
Derivative instruments	(1.0)	(2.3)
Total	46.0	64.0
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Investments in pooled funds
Fair value measurements
Investments	41.2	47.9
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Fixed income securities
Fair value measurements
Investments	$ 5.8	$ 18.4