Additional Details Related to Certain Balance Sheet Captions (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Other current assets:
Prepaid taxes	$ 47.0	$ 83.3
Prepaid expenses	65.7	66.9
Other	28.1	29.4
Total other current assets	140.8	179.6
Other assets:
Investments in joint ventures	26.3	28.7
Deposits for real-estate leases	10.8	11.4
Indemnification assets related to acquisitions	16.5	19.2
Fixed maturity and other open ended mutual funds	32.7	55.0
Other	25.9	26.1
Total other assets	112.2	140.4
Accounts payable and accrued liabilities:
Salaries and benefits	89.3	83.0
Incentive compensation	151.1	137.2
Accrued settlement charge	863.8
Customer credits, advanced payments and advanced billings	28.4	24.6
Self-insurance reserves	11.1	19.7
Dividends	78.5	78.2
Professional service fees	40.4	54.5
Interest accrued on debt	59.2	59.4
Accounts payable	28.4	22.2
Income taxes (see Note 15)	16.8	11.5
Restructuring (see Note 9)	6.3
Pension and other retirement employee benefits (see Note 13)	6.1	6.2
Other	64.9	70.1
Total accounts payable and accrued liabilities	1,444.3	566.6
Other liabilities:
Pension and other retirement employee benefits (see Note 12)	264.1	261.7
Deferred rent-non-current portion	98.3	98.4
Interest accrued on UTPs	34.1	27.9
Legacy and other tax matters	1.2	1.7
Other	27.5	27.5
Total other liabilities	$ 425.2	$ 417.2