Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 36.8	$ 1.0
Warrants		0.4
Contingent consideration associated with CDI acquisition	0.8	0.8
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	0.2	1.0
Warrants		0.0
Contingent consideration associated with CDI acquisition	0.0	0.0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 36.6	0.0
Warrants		0.0
Contingent consideration associated with CDI acquisition		0.0
Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 0.0	0.0
Warrants		0.4
Contingent consideration associated with CDI acquisition	$ 0.8	$ 0.8