Fair Value Measurements (Narrative) (Details) shares in Millions, $ in Millions	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security	Dec. 31, 2016 shares	Dec. 31, 2015 shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for Sale	$ 24,627.5	$ 26,699.9
Visa Class B
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares issued (in shares) | shares			1.1	1.0
LEVEL 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of available for sale securities portfolio | security	1,018	1,163
Available for Sale	$ 21,800.0	$ 24,000.0
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.200
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Measurement Input, Discount Rate | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input		0.150
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Measurement Input, Discount Rate | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input		0.200
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Measurement Input, Discount Rate | WEIGHTED-AVERAGE INPUT VALUES
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.200	0.172
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 5.1