Deposits - Scheduled Maturity of Total Time Deposits (Details) $ in Millions	Dec. 31, 2025 USD ($)
Time Deposits [Line Items]
1 Year or Less	$ 6,567.7
Over 1 Year to 2 Years	21.5
Over 2 Years to 3 Years	13.5
Over 3 Years to 4 Years	2.4
Over 4 Years to 5 Years	1.4
Over 5 Years	0.0
Total	6,606.5
U.S. OFFICE
Time Deposits [Line Items]
1 Year or Less	5,572.4
Over 1 Year to 2 Years	21.5
Over 2 Years to 3 Years	13.5
Over 3 Years to 4 Years	2.4
Over 4 Years to 5 Years	1.4
Over 5 Years	0.0
Total	5,611.2
NON-U.S. OFFICES
Time Deposits [Line Items]
1 Year or Less	995.3
Over 1 Year to 2 Years	0.0
Over 2 Years to 3 Years	0.0
Over 3 Years to 4 Years	0.0
Over 4 Years to 5 Years	0.0
Over 5 Years	0.0
Total	$ 995.3