Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring $ in Millions	Dec. 31, 2016 USD ($)
Assets:
Trading securities	$ 22.0
Liabilities:
Contingent consideration associated with CDI acquisition	0.3
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Trading securities	2.5
Liabilities:
Contingent consideration associated with CDI acquisition	0.0
Significant Other Observable Inputs (Level 2)
Assets:
Trading securities	19.5
Liabilities:
Contingent consideration associated with CDI acquisition	0.3
Unobservable Inputs (Level 3)
Assets:
Trading securities	0.0
Liabilities:
Contingent consideration associated with CDI acquisition	$ 0.0