Financial Instruments and Derivative Instruments - Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 29, 2025	Dec. 31, 2024
Interest Rate Swap
Assets
Derivative assets	$ 2.2
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Prepaid Expense and Other Assets, Current
Liabilities
Derivative liabilities	$ 0.7
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Current
Interest Rate Swap \| Prepaid Expenses and Other Current Assets
Assets
Derivative assets		$ 2.9
Interest Rate Swap \| Other Noncurrent Assets
Assets
Derivative assets		0.9
Interest Rate Swap \| Accrued Expenses and Other Liabilities
Liabilities
Derivative liabilities		0.7
Interest Rate Swap \| Other Non-current Liabilities
Liabilities
Derivative liabilities		0.3
Fair value measured on a recurring basis
Assets
Plan asset for deferred compensation	$ 2.7	2.5
Total assets	4.9	6.8
Liabilities
Plan liability for deferred compensation	2.7	2.5
Total liabilities	3.6	3.5
Fair value measured on a recurring basis \| Interest Rate Swap
Assets
Derivative assets	2.2	3.8
Liabilities
Derivative liabilities	0.7	1.0
Fair value measured on a recurring basis \| Forward exchange contracts
Assets
Derivative assets		0.5
Liabilities
Derivative liabilities	0.2
Fair value measured on a recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Plan asset for deferred compensation	2.7	2.5
Total assets	2.7	2.5
Liabilities
Plan liability for deferred compensation	2.7	2.5
Total liabilities	2.7	2.5
Fair value measured on a recurring basis \| Significant Other Observable Inputs (Level 2)
Assets
Total assets	2.2	4.3
Liabilities
Total liabilities	0.9	1.0
Fair value measured on a recurring basis \| Significant Other Observable Inputs (Level 2) \| Interest Rate Swap
Assets
Derivative assets	2.2	3.8
Liabilities
Derivative liabilities	0.7	1.0
Fair value measured on a recurring basis \| Significant Other Observable Inputs (Level 2) \| Forward exchange contracts
Assets
Derivative assets		$ 0.5
Liabilities
Derivative liabilities	$ 0.2

WATTS WATER TECHNOLOGIES INC 10-Q