Supplemental Guarantor Information - Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations	$ 559.0	$ 205.1
Operating activities
Net cash provided by (used for) operating activities	(256.3)	(167.6)
Investing activities
Capital expenditures	(16.8)	(11.5)
Proceeds from sale of property and equipment	0.3	0.0
Proceeds from (payments due to) the sale of businesses, net	0.7	(13.8)
Acquisitions, net of cash acquired	(287.2)	(0.9)
Net intercompany loan activity	0.0	0.0
Payments for (Proceeds from) Other Investing Activities	(1.5)	0.0
Net cash provided by (used for) investing activities of continuing operations	(304.5)	(26.2)
Net cash used for investing activities of discontinued operations	0.0	(5.0)
Net cash used for investing activities	(304.5)	(31.2)
Financing activities
Net receipts of commercial paper and revolving long-term debt	584.1	417.5
Net change in advances to subsidiaries	0.0	0.0
Shares issued to employees, net of shares withheld	5.9	0.9
Repurchases of ordinary shares	0.0	(150.0)
Dividends paid	(31.0)	(63.3)
Net cash provided by (used for) financing activities	559.0	997.8
Cash Provided by (Used in) Financing Activities, Discontinued Operations	0.0	792.7
Change in cash held for sale	0.0	(809.7)
Effect of exchange rate changes on cash and cash equivalents	6.4	(4.8)
Change in cash and cash equivalents	4.6	(15.5)
Cash and cash equivalents, beginning of period	74.3	86.3
Cash and cash equivalents, end of period	78.9	70.8
Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(82.6)
Operating activities
Net cash provided by (used for) operating activities	(31.8)	82.8
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	0.0	0.0
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash provided by (used for) investing activities of continuing operations		0.0
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	0.0	0.0
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Net change in advances to subsidiaries	56.9	129.8
Shares issued to employees, net of shares withheld	5.9	0.9
Repurchases of ordinary shares		(150.0)
Dividends paid	(31.0)	(63.3)
Net cash provided by (used for) financing activities	31.8	(82.6)
Cash Provided by (Used in) Financing Activities, Discontinued Operations		0.0
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.2
Cash and cash equivalents, beginning of period	0.1	0.0
Cash and cash equivalents, end of period	0.1	0.2
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(109.7)
Operating activities
Net cash provided by (used for) operating activities	57.1	111.6
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	0.0	(1.9)
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash provided by (used for) investing activities of continuing operations		(1.9)
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	0.0	(1.9)
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Net change in advances to subsidiaries	(57.1)	(109.7)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares		0.0
Dividends paid	0.0	0.0
Net cash provided by (used for) financing activities	(57.1)	(109.7)
Cash Provided by (Used in) Financing Activities, Discontinued Operations		0.0
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	0.0	0.0
Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		132.2
Operating activities
Net cash provided by (used for) operating activities	54.6	109.3
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	(627.8)	(262.6)
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash provided by (used for) investing activities of continuing operations		(262.6)
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	(627.8)	(262.6)
Financing activities
Net receipts of commercial paper and revolving long-term debt	605.2	223.8
Net change in advances to subsidiaries	(33.6)	(91.6)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares		0.0
Dividends paid	0.0	0.0
Net cash provided by (used for) financing activities	571.6	132.2
Cash Provided by (Used in) Financing Activities, Discontinued Operations		0.0
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	1.5	21.1
Change in cash and cash equivalents	(0.1)	0.0
Cash and cash equivalents, beginning of period	0.1	0.0
Cash and cash equivalents, end of period	0.0	0.0
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(49.0)
Operating activities
Net cash provided by (used for) operating activities	(172.8)	4.3
Investing activities
Capital expenditures	(16.8)	(11.5)
Proceeds from sale of property and equipment	0.3	0.0
Proceeds from (payments due to) the sale of businesses, net	0.7	(13.8)
Acquisitions, net of cash acquired	(287.2)	(0.9)
Net intercompany loan activity	(21.9)	103.1
Payments for (Proceeds from) Other Investing Activities	1.5
Net cash provided by (used for) investing activities of continuing operations		76.9
Net cash used for investing activities of discontinued operations		(5.0)
Net cash used for investing activities	(326.4)	71.9
Financing activities
Net receipts of commercial paper and revolving long-term debt	(21.1)	193.7
Net change in advances to subsidiaries	520.1	(242.7)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares		0.0
Dividends paid	0.0	0.0
Net cash provided by (used for) financing activities	499.0	743.7
Cash Provided by (Used in) Financing Activities, Discontinued Operations		792.7
Change in cash held for sale		(809.7)
Effect of exchange rate changes on cash and cash equivalents	4.9	(25.9)
Change in cash and cash equivalents	4.7	(15.7)
Cash and cash equivalents, beginning of period	74.1	86.3
Cash and cash equivalents, end of period	78.8	70.6
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		314.2
Operating activities
Net cash provided by (used for) operating activities	(163.4)	(475.6)
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	649.7	161.4
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash provided by (used for) investing activities of continuing operations		161.4
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	649.7	161.4
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Net change in advances to subsidiaries	(486.3)	314.2
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares		0.0
Dividends paid	0.0	0.0
Net cash provided by (used for) financing activities	(486.3)	314.2
Cash Provided by (Used in) Financing Activities, Discontinued Operations		0.0
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	$ 0.0	$ 0.0