Mortgage Servicing Assets (Tables)

9 Months Ended

Sep. 30, 2018

Servicing Asset [Abstract]

Changes in Carrying Amount of Mortgage Servicing Assets

Changes in the carrying amount of residential mortgage servicing assets are summarized as follows:

	Three months ended September 30,						Nine months ended September 30,
in millions	2018			2017			2018			2017
Balance at beginning of period	$	34		$	29		$	31		$	28
Servicing retained from loan sales	2			2			7			5
Purchases	—			—			—			—
Amortization	(1		)	(1		)	(3		)	(3		)
Balance at end of period	$	35		$	30		$	35		$	30
Fair value at end of period	$	49		$	34		$	49		$	34

Changes in the carrying amount of commercial mortgage servicing assets are summarized as follows:

	Three months ended September 30,						Nine months ended September 30,
in millions	2018			2017			2018			2017
Balance at beginning of period	$	451		$	373		$	412		$	356
Servicing retained from loan sales	25			24			81			71
Purchases	17			10			50			24
Amortization	(25		)	(22		)	(75		)	(66		)
Balance at end of period	$	468		$	385		$	468		$	385
Fair value at end of period	$	672		$	508		$	672		$	508

Schedule of Range and Weighted-Average of Significant Unobservable Inputs

The range and weighted-average of the significant unobservable inputs used to fair value our mortgage servicing assets at September 30, 2018, and September 30, 2017, along with the valuation techniques, are shown in the following table:

dollars in millions		September 30, 2018	September 30, 2017
Valuation Technique	Significant Unobservable Input	Range (Weighted Average)
Discounted cash flow	Prepayment speed	8.27 - 55.15% (9.35%)	7.95 - 32.49% (10.15%)
	Discount rate	7.50 - 10.00% (7.54%)	8.50 - 11.00% (8.55%)
	Servicing cost	$62 - $4,375 ($67.76)	$76 - $3,335 ($82.19)

The range and weighted average of the significant unobservable inputs used to determine the fair value of our commercial mortgage servicing assets at September 30, 2018, and September 30, 2017, along with the valuation techniques, are shown in the following table: 

dollars in millions		September 30, 2018	September 30, 2017
Valuation Technique	Significant Unobservable Input	Range (Weighted Average)
Discounted cash flow	Expected defaults	1.00 - 3.00% (1.16%)	1.00 - 3.00% (1.20%)
	Residual cash flows discount rate	7.00 - 15.00% (9.10%)	7.00 - 15.00% (8.90%)
	Escrow earn rate	2.38 - 3.94% (3.07%)	.80 - 3.00% (2.40%)
	Servicing cost	$150 - $38,500 ($1,445)	$150 - $38,500 ($1,468)
	Loan assumption rate	0.00 - 3.22% (1.34%)	0.00 - 3.00% (1.24%)
	Percentage late	0.00 - 2.00% (.20%)	0.00 - 2.00% (.27%)