Borrowings and Contractual Commitments (Tables)

12 Months Ended

Dec. 31, 2017

Short-term Debt [Line Items]

Schedule of Short-term Debt [Table Text Block]

Short-term borrowings at December 31 consisted of the following:

	2017				2016
(Dollars in millions)	Balance		Interest Rate		Balance		Interest Rate
Funds purchased		$2,561	1.33	%		$2,116	0.55	%
Securities sold under agreements to repurchase	1,503		1.39		1,633		0.55
Other short-term borrowings	717		1.00		1,015		0.56
Total short-term borrowings		$4,781				$4,764

Debt Instrument [Line Items]

Schedule of Long-term Debt Instruments [Table Text Block]

Long-term debt at December 31 consisted of the following:

	2017				2016
(Dollars in millions)	Maturity Date(s)	Interest Rate(s)	Balance		Balance
Parent Company Only:
Senior, fixed rate	2018 - 2028	2.35% - 6.00%		$3,379		$3,818
Senior, variable rate	2018 - 2019	0.25 - 1.53	267		314
Subordinated, fixed rate	2026	6.00	200		200
Junior subordinated, variable rate	2027 - 2028	2.09 - 2.32	628		627
Total			4,474		4,959
Less: Debt issuance costs			8		9
Total Parent Company debt			4,466		4,950
Subsidiaries 1:
Senior, fixed rate 2	2018 - 2057	0.80 - 9.10	3,609		2,539
Senior, variable rate	2020 - 2043	1.04 - 1.84	512		2,613
Subordinated, fixed rate	2018 - 2026	3.30 - 7.25	1,206		1,651
Total			5,327		6,803
Less: Debt issuance costs			8		5
Total subsidiaries debt			5,319		6,798
Total long-term debt 3				$9,785		$11,748

Schedule of Maturities of Long-term Debt [Table Text Block]

Maturities of long-term debt at December 31, 2017 were as follows:

(Dollars in millions)	Parent Company		Subsidiaries
2018		$874		$361
2019	792		27
2020	—		1,508
2021	965		4
2022	990		1,022
Thereafter	853		2,405
Total maturities	4,474		5,327
Less: Debt issuance costs	8		8
Total long-term debt		$4,466		$5,319