Derivative Instruments - Summary of Notional Amount of Derivatives and Other Financial Instruments (Details) £ in Thousands, $ in Thousands, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2025 CAD ($)	Sep. 30, 2025 GBP (£)	Dec. 31, 2024 CAD ($)	Dec. 31, 2024 GBP (£)	Sep. 30, 2025 GBP (£)	Sep. 30, 2025 USD ($)	Dec. 31, 2024 GBP (£)	Dec. 31, 2024 USD ($)
Denominated in Canadian Dollars | Derivative Instruments Not Designated
Derivatives, Fair Value [Line Items]
Derivative asset	$ 80,000		$ 80,000
Denominated in Canadian Dollars | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset	5,702,699		2,904,028
Net investment hedges	250,000		250,000
Denominated in Canadian Dollars | Cash Flow Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset	$ 32,000		$ 0
Denominated in Pounds Sterling | Derivative Instruments Not Designated | Sales Contracts
Derivatives, Fair Value [Line Items]
Derivative asset | £					£ 270,000
Denominated in Pounds Sterling | Derivative Instruments Not Designated | Purchase Contracts
Derivatives, Fair Value [Line Items]
Derivative asset | £							£ 0
Denominated in Pounds Sterling | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset | £					£ 1,530,708		£ 1,430,708
Net investment hedges | £		£ 1,050,000		£ 1,050,000
Denominated in U.S. Dollars | Cash Flow Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset						$ 0		$ 22,601
Denominated in U.S. Dollars | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset						$ 550,000		$ 550,000