Investments (Schedule of Maturities of Available-for-Sale Debt Securities and Held-to-Maturity Debt Securities) (Details) - USD ($) $ in Millions		Mar. 31, 2020		Dec. 31, 2019
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		$ 1,122
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		8,460
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		434
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		0
Available-for-sale investment securities, amortized cost	[1]	10,016		$ 10,173
Held-to-maturity investment securities, debt maturities, one year or less, amortized cost		0
Held-to-maturity investment securities, debt maturities, after one year through five years, amortized cost		0
Held-to-maturity investment securities, debt maturities, after five years through ten years, amortized cost		0
Held-to-maturity investment securities, debt maturities, after ten years, amortized cost		279
Held-to-maturity investment securities, amortized cost	[2]	279		272
Available-for-sale investment securities, debt maturities, one year or less, fair value		1,137
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		8,914
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		452
Available-for-sale investment securities, debt maturities, after ten years, fair value		0
Available-for-sale investment securities, fair value	[1]	10,503		10,323
Held-to-maturity investment securities, debt maturities, one year or less, fair value		0
Held-to-maturity investment securities, debt maturities, after one year through five years, fair value		0
Held-to-maturity investment securities, debt maturities, after five years through ten years, fair value		0
Held-to-maturity investment securities, debt maturities, after ten years, fair value		288
Held-to-maturity investment securities, fair value	[2]	288		274
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		1,122
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		8,386
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		126
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		0
Available-for-sale investment securities, amortized cost	[1]	9,634		9,759
Available-for-sale investment securities, debt maturities, one year or less, fair value		1,137
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		8,837
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		136
Available-for-sale investment securities, debt maturities, after ten years, fair value		0
Available-for-sale investment securities, fair value	[1]	10,110		9,906
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost	[3]	0
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost	[3]	74
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost	[3]	308
Available-for-sale investment securities, debt maturities, after ten years, amortized cost	[3]	0
Available-for-sale investment securities, amortized cost	[1]	382	[3]	414
Held-to-maturity investment securities, debt maturities, one year or less, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after one year through five years, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after five years through ten years, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after ten years, amortized cost	[3]	279
Held-to-maturity investment securities, amortized cost	[2],[4]	279	[3]	272
Available-for-sale investment securities, debt maturities, one year or less, fair value	[3]	0
Available-for-sale investment securities, debt maturities, after one year through five years, fair value	[3]	77
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value	[3]	316
Available-for-sale investment securities, debt maturities, after ten years, fair value	[3]	0
Available-for-sale investment securities, fair value	[1]	393	[3]	417
Held-to-maturity investment securities, debt maturities, one year or less, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after one year through five years, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after five years through ten years, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after ten years, fair value	[3]	288
Held-to-maturity investment securities, fair value	[2],[4]	$ 288	[3]	$ 274

[1] Available-for-sale investment securities are reported at fair value.

[2] Held-to-maturity investment securities are reported at amortized cost.

[3] Maturities of residential mortgage-backed securities are reflective of the contractual maturities of the investment.

[4] Amounts represent residential mortgage-backed securities that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.