Debt - Short-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Short-Term Debt
Short-term debt	$ 177.6	$ 27.7
Weighted-average interest rates on short-term borrowings (as a percent)	4.80%	6.30%
Commercial paper \| Principal Life Insurance Company
Short-Term Debt
Short-term debt	$ 149.6
Credit facility maturing September 2031 \| Principal Life Insurance Company
Short-Term Debt
Credit facilities	900.0
Secured CLO borrowings \| Principal CLO warehouse
Short-Term Debt
Credit facilities	80.0
Short-term debt	$ 28.0
Unsecured lines of credit \| Principal Compania de Seguros de Vida Chile S.A.
Short-Term Debt
Credit facilities		$ 85.6
Short-term debt		24.8
Unsecured lines of credit \| Principal International de Chile S.A.
Short-Term Debt
Credit facilities		24.1
Short-term debt		2.9
Credit facility maturing in October 2027 \| Principal Life Insurance Company
Short-Term Debt
Credit facilities		$ 800.0

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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