Long-Term Debt (Details) £ in Millions, $ in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) item	Mar. 31, 2020 GBP (£)	Mar. 31, 2020 AUD ($)	Dec. 31, 2019 USD ($)
Long Term Debt
Total long-term debt	$ 2,620.7			$ 2,360.3
Less: current portion	(104.6)			(103.3)
Net long-term debt	2,516.1			2,257.0
US Credit Agreement Revolving Credit Line
Long Term Debt
Total long-term debt	350.0			45.0
Maximum credit available	700.0
Revolving loans solely for future U.S. acquisitions	250.0
Future borrowings available for foreign acquisitions	150.0
Maximum amount available for letters of credit	$ 50.0
Incremental interest rate for uncollateralized borrowings in excess of borrowing base (as a percent)	1.25%
Balance outstanding under credit agreement	$ 350.0
US Credit Agreement Revolving Credit Line | LIBOR
Long Term Debt
Line of credit basis spread on variable rate (as a percent)	1.75%
UK Credit Agreement Revolving Credit Line
Long Term Debt
Total long-term debt	$ 117.9			165.8
Maximum credit available | £		£ 150.0
Additional facility capacity under accordion feature | £		100.0
Balance outstanding under credit agreement	$ 124.2	100.1
UK Credit Agreement Revolving Credit Line | Minimum | LIBOR
Long Term Debt
Line of credit basis spread on variable rate (as a percent)	1.10%
UK Credit Agreement Revolving Credit Line | Maximum | LIBOR
Long Term Debt
Line of credit basis spread on variable rate (as a percent)	2.10%
UK Credit Agreement Overdraft Line of Credit
Long Term Debt
Total long-term debt	$ 6.3
Maximum credit available | £		52.0
Amount of demand overdraft lines of credit available during specified time periods each year | £		£ 40.0
Senior Subordinated Notes
Long Term Debt
Domestic Subsidiaries ownership guaranteeing obligations (as a percent)	100.00%	100.00%	100.00%
Change of control, redemption price as a percentage of principal	101.00%
Sale of assets, redemption price as percentage of principal	100.00%
5.50% senior subordinated notes due 2026
Long Term Debt
Total long-term debt	$ 495.9			$ 495.7
Interest rate (as a percent)	5.50%	5.50%	5.50%	5.50%
Principal amount	$ 500.0
5.50% senior subordinated notes due 2026 | Debt Redemption Prior to May 15, 2021
Long Term Debt
Interest rate (as a percent)	5.50%	5.50%	5.50%
Percentage of principal amount at which the entity may redeem the notes	100.00%
5.50% senior subordinated notes due 2026 | Debt Instrument Redemption Period On or After May 15, 2021
Long Term Debt
Interest rate (as a percent)	5.50%	5.50%	5.50%
5.375% senior subordinated notes due 2024
Long Term Debt
Total long-term debt	$ 298.2			$ 298.0
Interest rate (as a percent)	5.375%	5.375%	5.375%	5.375%
Principal amount	$ 300.0
5.75% senior subordinated notes due 2022
Long Term Debt
Total long-term debt	$ 547.9			$ 547.6
Interest rate (as a percent)	5.75%	5.75%	5.75%	5.75%
Principal amount	$ 550.0
3.75% senior subordinated notes due 2020
Long Term Debt
Total long-term debt	$ 299.5			$ 299.2
Interest rate (as a percent)	3.75%	3.75%	3.75%	3.75%
Principal amount	$ 300.0
Percentage of principal amount at which the entity may redeem the notes	100.00%
Australia capital loan agreement
Long Term Debt
Total long-term debt	$ 27.1			$ 31.7
Maximum credit available			$ 50.0
Debt term	5 years
Call period	90 days
Maximum amount of debt guaranteed by the Company's U.S. parent company	$ 50.0
Balance outstanding under credit agreement	$ 27.1		44.2
Number of facilities | item	2
Australia capital loan agreement | Australian BBSW 30-Day Bill Rate
Long Term Debt
Base rate of interest on loans	30-day Bill Rate
Line of credit basis spread on variable rate (as a percent)	3.00%
Australia working capital loan agreement
Long Term Debt
Total long-term debt	$ 12.3
Maximum credit available			50.0
Debt term	1 year
Call period	90 days
Maximum amount of debt guaranteed by the Company's U.S. parent company	$ 50.0
Balance outstanding under credit agreement	$ 12.3		$ 20.0
Australia working capital loan agreement | Australian BBSW 30-Day Bill Rate
Long Term Debt
Base rate of interest on loans	30-day Bill Rate
Line of credit basis spread on variable rate (as a percent)	3.00%
Mortgage facilities
Long Term Debt
Total long-term debt	$ 416.7			423.2
Balance outstanding under credit agreement	416.7
Other debt
Long Term Debt
Total long-term debt	$ 48.9			$ 54.1