Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 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	$ 68.8	$ 73.5
Fair value measured on a recurring basis | Estimated Fair Value
Fair value measurements
Deferred compensation liabilities	(52.6)	(43.8)
Interest rate swap liability	(1.6)	(2.3)
Total	725.3	671.9
Fair value measured on a recurring basis | Estimated Fair Value | Equity securities
Fair value measurements
Investments	712.8	651.7
Fair value measured on a recurring basis | Estimated Fair Value | Investments in pooled funds
Fair value measurements
Investments	40.8	47.9
Fair value measured on a recurring basis | Estimated Fair Value | Fixed income securities
Fair value measurements
Investments	25.9	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	(52.6)	(43.8)
Total	660.2	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	712.8	651.7
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2)
Fair value measurements
Interest rate swap liability	(1.6)	(2.3)
Total	65.1	64.0
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Investments in pooled funds
Fair value measurements
Investments	40.8	47.9
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Fixed income securities
Fair value measurements
Investments	$ 25.9	$ 18.4