Financing Arrangements - Credit Agreement (Details) € in Millions				1 Months Ended	12 Months Ended
	Dec. 20, 2016 USD ($)	Dec. 16, 2016 USD ($)	Feb. 12, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 16, 2016 EUR (€)
Credit Agreement
Borrowings outstanding					$ 499,500,000	$ 653,600,000
Stand-by letters of credit outstanding					25,700,000	25,600,000
Term Loan due February 2021
Credit Agreement
Borrowings outstanding					$ 277,500,000	300,000,000
Letters of credit
Credit Agreement
Term of debt					1 year
Credit Agreement
Credit Agreement
Term of debt			5 years
Sublimit on letters of credit			$ 100,000,000
Unused and available credit under the credit agreement						327,300,000
Stand-by letters of credit outstanding						$ 25,700,000
Eurocurrency rate loans | LIBOR | Minimum
Credit Agreement
Interest rate added to base rate (as a percent)					0.975%
Eurocurrency rate loans | LIBOR | Maximum
Credit Agreement
Interest rate added to base rate (as a percent)					1.45%
Base rate loans and swing line loans | LIBOR
Credit Agreement
Interest rate added to base rate (as a percent)					1.00%
Base rate loans and swing line loans | LIBOR | Minimum
Credit Agreement
Interest rate added to base rate (as a percent)					0.00%
Base rate loans and swing line loans | LIBOR | Maximum
Credit Agreement
Interest rate added to base rate (as a percent)					0.45%
Base rate loans and swing line loans | Federal funds
Credit Agreement
Interest rate added to base rate (as a percent)					0.50%
Senior unsecured revolving credit facility
Credit Agreement
Borrowing capacity			$ 500,000,000
Amount drawn					$ 147,000,000
Interest rate on revolving credit facility (as a percent)					2.56%
Repayment of debt	$ 113,000,000
Term loan facility | Term Loan due February 2021
Credit Agreement
Term of debt			5 years
Face amount			$ 300,000,000
Interest rate on term loan facility (as a percent)					2.67%
First year (as a percent)			0.00%
Second and third years (as a percent)			7.50%
Fourth and fifth years (as a percent)			10.00%
Amount drawn				$ 300,000,000
Required payment					$ 22,500,000
Term loan facility | LIBOR | Minimum | Term Loan due February 2021
Credit Agreement
Interest rate added to base rate (as a percent)					1.125%
Term loan facility | LIBOR | Maximum | Term Loan due February 2021
Credit Agreement
Interest rate added to base rate (as a percent)					1.75%
Facility Agreement | Watts International
Credit Agreement
Borrowing capacity | €							€ 110
Term of debt		364 days
Frequency of interest payment, first option		1 month
Frequency of interest payment, second option		2 months
Frequency of interest payment, third option		3 months
Facility Agreement | Euro Libor | Watts International
Credit Agreement
Minimum base rate (as a percent)		$ 0
Interest rate added to base rate (as a percent)		1.875%