Fair Value Measurements (Fair Value Measurements Using Significant Unobservable Inputs) (Details) - Recurring - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	$ 383	$ 558	$ 402	$ 545
Total unrealized gains/(losses) recorded in earnings	(29)	(22)	(124)	(42)
Total realized gains/(losses) recorded in earnings	0	0	0	1
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	51	74	173	220
Sales	(17)	(73)	(41)	(144)
Settlements	(14)	(18)	(36)	(61)
Transfers In (Out)	0	0	0	0
Balance at End of Period	374	519	374	519
Liabilities, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period		(120)		(166)
Total unrealized gains/(losses) recorded in earnings		0		(2)
Total realized gains/(losses) recorded in earnings		0		(3)
Total unrealized gains/(losses) recorded in OCI		0		0
Purchases / Originations		0		0
Sales		0		24
Settlements		4		31
Transfers In (Out)		0		0
Balance at End of Period		(116)		(116)
Rate lock commitments
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	82	30	26	31
Total unrealized gains/(losses) recorded in earnings	33	53	153	60
Total realized gains/(losses) recorded in earnings	0	0	0	0
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	116	81	303	272
Sales	(150)	(104)	(371)	(276)
Settlements	(18)	(16)	(48)	(43)
Balance at End of Period	63	44	63	44
Liabilities, Unobservable Input Reconciliation [Roll Forward]
Transfers In (Out)	0	0
Long-term debt
Liabilities, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period		(36)		(84)
Total unrealized gains/(losses) recorded in earnings		0		0
Total realized gains/(losses) recorded in earnings		0		(3)
Total unrealized gains/(losses) recorded in OCI		0		0
Purchases / Originations		0		0
Sales		0		24
Settlements		4		31
Transfers In (Out)		0		0
Balance at End of Period		(32)		(32)
DOJ litigation settlement
Liabilities, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	(84)	(84)	(84)	(82)
Total unrealized gains/(losses) recorded in earnings	24	0	24	(2)
Total realized gains/(losses) recorded in earnings	0	0	0	0
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers In (Out)	0	0	0	0
Balance at End of Period	(60)	(84)	(60)	(84)
Rate lock commitments
Liabilities, Unobservable Input Reconciliation [Roll Forward]
Transfers In (Out)			0	0
Second mortgage loans
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	38	48	42	53
Total unrealized gains/(losses) recorded in earnings	(2)	0	(1)	2
Total realized gains/(losses) recorded in earnings	0	0	0	1
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	0	0	0	0
Sales	0	0	0	0
Settlements	(3)	(3)	(8)	(11)
Transfers In (Out)	8	0	8	0
Balance at End of Period	41	45	41	45
HELOC loans
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	44	93	64	132
Total unrealized gains/(losses) recorded in earnings	6	2	3	(4)
Total realized gains/(losses) recorded in earnings	0	0	0	0
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	0	0	0	0
Sales	0	0	0	0
Settlements	(11)	(15)	(28)	(48)
Transfers In (Out)	(8)	0	(8)	0
Balance at End of Period	31	80	31	80
Mortgage servicing rights
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	301	317	296	258
Total unrealized gains/(losses) recorded in earnings	(33)	(24)	(126)	(40)
Total realized gains/(losses) recorded in earnings	0	0	0	0
Total unrealized gains/(losses) recorded in OCI	0	0	0	0
Purchases / Originations	51	74	173	220
Sales	(17)	(73)	(41)	(144)
Settlements	0	0	0	0
Transfers In (Out)	0	0	0	0
Balance at End of Period	$ 302	294	$ 302	294
Other investments
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period		100		100
Total unrealized gains/(losses) recorded in earnings		0		0
Total realized gains/(losses) recorded in earnings		0		0
Total unrealized gains/(losses) recorded in OCI		0		0
Purchases / Originations		0		0
Sales		0		0
Settlements		0		0
Transfers In (Out)		0		0
Balance at End of Period		100		100
Municipal obligation
Assets, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period				2
Total unrealized gains/(losses) recorded in earnings				0
Total realized gains/(losses) recorded in earnings				0
Total unrealized gains/(losses) recorded in OCI				0
Purchases / Originations				0
Sales				0
Settlements				(2)
Transfers In (Out)				0
Balance at End of Period		$ 0		$ 0