AVAILABLE-FOR-SALE SECURITIES (Tables)

3 Months Ended

Dec. 31, 2020

Debt Securities, Available-for-sale [Abstract]

Amortized Cost and Estimated Fair Values of Available-For-Sale Securities

The following table details the amortized costs and fair values of our available-for-sale securities.

$ in millions	Cost basis		Gross unrealized gains		Gross unrealized losses		Fair value
December 31, 2020
Agency residential MBS	$	4,421	$	72	$	(3)	$	4,490
Agency commercial MBS	1,161		17		(4)		1,174
Agency CMOs	2,308		17		(5)		2,320
Other securities	15		1		—		16
Total available-for-sale securities	$	7,905	$	107	$	(12)	$	8,000
September 30, 2020
Agency residential MBS	$	4,064	$	74	$	(3)	$	4,135
Agency commercial MBS	948		22		(1)		969
Agency CMOs	2,504		27		(1)		2,530
Other securities	15		1		—		16
Total available-for-sale securities	$	7,531	$	124	$	(5)	$	7,650

Contractual Maturities, Amortized Cost, Carrying Values, and Current Yields for Available-For-Sales Securities

The following table details the contractual maturities, amortized costs, carrying values and current yields for our available-for-sale securities.  Since our MBS and CMO available-for-sale securities are backed by mortgages, actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations without prepayment penalties. As of December 31, 2020, the duration of our available-for-sale securities portfolio was approximately 3 years.

	December 31, 2020
$ in millions	Within one year			After one but within five years			After five but within ten years			After ten years			Total
Agency residential MBS
Amortized cost	$	—		$	37		$	1,639		$	2,745		$	4,421
Carrying value	$	—		$	38		$	1,669		$	2,783		$	4,490
Agency commercial MBS
Amortized cost	$	25		$	148		$	845		$	143		$	1,161
Carrying value	$	25		$	151		$	853		$	145		$	1,174
Agency CMOs
Amortized cost	$	—		$	1		$	63		$	2,244		$	2,308
Carrying value	$	—		$	1		$	64		$	2,255		$	2,320
Other securities
Amortized cost	$	—		$	7		$	8		$	—		$	15
Carrying value	$	—		$	7		$	9		$	—		$	16
Total available-for-sale securities
Amortized cost	$	25		$	193		$	2,555		$	5,132		$	7,905
Carrying value	$	25		$	197		$	2,595		$	5,183		$	8,000
Weighted-average yield	2.13		%	2.06		%	1.44		%	1.28		%	1.35		%

Available-For-Sale Securities in a Continuous Unrealized Loss Position

The following table details the gross unrealized losses and fair values of securities that were in a loss position at the reporting period end, aggregated by investment category and length of time the individual securities have been in a continuous unrealized loss position.

	Less than 12 months				12 months or more				Total
$ in millions	Estimated fair value		Unrealized losses		Estimated fair value		Unrealized losses		Estimated fair value		Unrealized losses
December 31, 2020
Agency residential MBS	$	827	$	(3)	$	—	$	—	$	827	$	(3)
Agency commercial MBS	493		(4)		—		—		493		(4)
Agency CMOs	1,042		(5)		—		—		1,042		(5)
Total	$	2,362	$	(12)	$	—	$	—	$	2,362	$	(12)
September 30, 2020
Agency residential MBS	$	966	$	(3)	$	—	$	—	$	966	$	(3)
Agency commercial MBS	177		(1)		—		—		177		(1)
Agency CMOs	410		(1)		—		—		410		(1)
Total	$	1,553	$	(5)	$	—	$	—	$	1,553	$	(5)