Contingencies, Commitments and Guarantees (Details Textual) $ in Millions		1 Months Ended	12 Months Ended
	Oct. 16, 2025 USD ($)	Aug. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) state	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Loss Contingencies [Line Items]
Total lease expense			$ 179.0	$ 189.0	$ 164.0
Lease liabilities			$ 1,136.0	$ 933.0
Weighted average remaining lease term			14 years	17 years
Weighted average lease discount rate (as a percent)			4.00%	4.00%
Commitments related to agreements with certain cobrand partners			$ 11,200.0
Maximum potential amount of undiscounted future payments			148.0	$ 1,000.0
Amount of related liability			11.0	10.0
Joint and Several Arrangement
Loss Contingencies [Line Items]
Maximum potential restoration exposure, not accrued			1,700.0
American Express National Bank
Loss Contingencies [Line Items]
Carrying value of Federal Reserve Bank shares held			132.0	132.0
Co-Tenant's Share | Joint and Several Arrangement
Loss Contingencies [Line Items]
Maximum potential restoration exposure, not accrued			$ 900.0
Maximum potential amount of undiscounted future payments				$ 1,000.0
Violation Of Federal Antitrust Law And Consumer Laws Class Action Case | David Moskowitz, et al.
Loss Contingencies [Line Items]
Number of states with remaining claims | state			8
Loss contingency, damages awarded		$ 12.5
Violation Of Federal Antitrust Law And Consumer Laws Class Action Case | David Moskowitz, etal
Loss Contingencies [Line Items]
Number of states with remaining claims | state			2
Kabbage Acquisition | KServicing Wind Down Corp.
Loss Contingencies [Line Items]
Loss contingency, damages sought	$ 746.0
Minimum
Loss Contingencies [Line Items]
Range of possible loss, in excess of accruals			$ 0.0
Financial commitments, period			5 years
Maximum
Loss Contingencies [Line Items]
Range of possible loss, in excess of accruals			$ 250.0
Financial commitments, period			10 years