Fair Values of Financial Instruments - Summary of Reconciliation of Acquisition Related Contingent Consideration (Parenthetical) (Detail) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
System Transformation Transactions [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Increase in acquisition related contingent consideration	$ 62.5

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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