Investments (Contractual Maturities Debt Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Held-to-maturity, Amortized cost
Total debt investment securities	$ 441	$ 636
Available-for-sale, Amortized cost
Available-for-sale	24,202	15,417
Due in one year or less	111
Due after one year through five years	1,461
Due after five years through 10 years	2,328
Due after 10 years	$ 20,302
Available-for-sale, Weighted average yield
Total debt investment securities	1.67%
Due in one year or less	2.08%
Due after one year through five years	1.91%
Due after five years through 10 years	1.78%
Due after 10 years	1.63%
Total investment securities, Amortized cost
Total debt investment securities	$ 24,643	$ 16,053
Due in one year or less	140
Due after one year through five years	1,592
Due after five years through 10 years	2,498
Due after 10 years	$ 20,413
Total investment securities, Weighted average yield
Total debt investment securities	1.69%
Due in one year or less	2.21%
Due after one year through five years	2.05%
Due after five years through 10 years	1.85%
Due after 10 years	1.64%
Municipal securities
Held-to-maturity, Amortized cost
Total debt investment securities	$ 441
Due in one year or less	29
Due after one year through five years	131
Due after five years through 10 years	170
Due after 10 years	$ 111
Held-to-maturity, Weighted average yield
Total debt investment securities	3.14%
Due in one year or less	2.71%
Due after one year through five years	3.53%
Due after five years through 10 years	2.81%
Due after 10 years	3.30%
Available-for-sale, Amortized cost
Available-for-sale	$ 1,652
Due in one year or less	111
Due after one year through five years	687
Due after five years through 10 years	490
Due after 10 years	$ 364
Available-for-sale, Weighted average yield
Total debt investment securities	2.36%
Due in one year or less	2.08%
Due after one year through five years	2.56%
Due after five years through 10 years	2.08%
Due after 10 years	2.46%
U.S. Treasury securities
Available-for-sale, Amortized cost
Available-for-sale	$ 155
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	$ 155
Available-for-sale, Weighted average yield
Total debt investment securities	1.28%
Due in one year or less	0.00%
Due after one year through five years	0.00%
Due after five years through 10 years	0.00%
Due after 10 years	1.28%
Agency securities
Available-for-sale, Amortized cost
Available-for-sale	$ 833
Due in one year or less	0
Due after one year through five years	327
Due after five years through 10 years	284
Due after 10 years	$ 222
Available-for-sale, Weighted average yield
Total debt investment securities	2.06%
Due in one year or less	0.00%
Due after one year through five years	1.32%
Due after five years through 10 years	2.41%
Due after 10 years	2.71%
Agency guaranteed mortgage-backed securities
Available-for-sale, Amortized cost
Available-for-sale	$ 20,549
Due in one year or less	0
Due after one year through five years	396
Due after five years through 10 years	1,381
Due after 10 years	$ 18,772
Available-for-sale, Weighted average yield
Total debt investment securities	1.61%
Due in one year or less	0.00%
Due after one year through five years	1.36%
Due after five years through 10 years	1.56%
Due after 10 years	1.62%
Small Business Administration loan-backed securities
Available-for-sale, Amortized cost
Available-for-sale	$ 938
Due in one year or less	0
Due after one year through five years	51
Due after five years through 10 years	113
Due after 10 years	$ 774
Available-for-sale, Weighted average yield
Total debt investment securities	1.30%
Due in one year or less	0.00%
Due after one year through five years	1.33%
Due after five years through 10 years	1.55%
Due after 10 years	1.26%
Other debt securities
Available-for-sale, Amortized cost
Available-for-sale	$ 75
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	60
Due after 10 years	$ 15
Available-for-sale, Weighted average yield
Total debt investment securities	2.16%
Due in one year or less	0.00%
Due after one year through five years	0.00%
Due after five years through 10 years	1.99%
Due after 10 years	2.83%