Goodwill and Other Identifiable Intangible Assets - Estimated Future Amortization Expense for Identifiable Intangible Assets (Detail) $ in Millions	Dec. 31, 2016 USD ($)
Expected Amortization Expense
Estimated amortization expense 2017	$ 95.5
Estimated amortization expense 2018	94.0
Estimated amortization expense 2019	91.6
Estimated amortization expense 2020	85.0
Estimated amortization expense 2021	$ 80.0