Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) segment	Sep. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment			4
Summary of Operations
Net interest income	$ 80	$ 73	$ 236	$ 211
Net gain on loan sales	94	68	259	242
Representation and warranty benefit	6	6	12	13
Other noninterest income (loss)	56	54	118	118
Total net interest income and noninterest income	236	201	625	584
(Provision) benefit for loan losses	(7)	1	9	18
Asset resolution	(2)	0	(6)	(13)
Depreciation and amortization expense	(8)	(6)	(23)	(17)
Other noninterest expense	(132)	(125)	(389)	(377)
Total noninterest expense	(142)	(131)	(418)	(407)
Income before income taxes	87	71	216	195
Provision for income taxes	30	24	73	70
Net income	57	47	143	125
Average balances
Loans held-for-sale	3,416	2,200	3,071	2,088
Loans with government guarantees	432	547	450	679
Loans held-for-investment	5,848	5,412	5,695	4,885
Total assets	14,148	12,305	13,711	11,663
Deposits	9,126	8,260	8,603	7,791
Intersegment Eliminations
Summary of Operations
Total net interest income and noninterest income	0	0	0	0
Mortgage Originations
Summary of Operations
Net interest income	21	18	61	52
Net gain on loan sales	95	72	251	255
Representation and warranty benefit	6	6	12	13
Other noninterest income (loss)	4	26	17	60
Total net interest income and noninterest income	126	122	341	380
(Provision) benefit for loan losses	0	0	0	0
Asset resolution	0		0	0
Depreciation and amortization expense	(2)	(1)	(4)	(2)
Other noninterest expense	(64)	(56)	(182)	(174)
Total noninterest expense	(66)	(57)	(186)	(176)
Income before income taxes	60	65	155	204
Provision for income taxes	0	0	0	0
Net income	60	65	155	204
Average balances
Loans held-for-sale	3,400	2,179	2,988	2,052
Loans with government guarantees	0	0	0	0
Loans held-for-investment	5	4	6	3
Total assets	4,238	2,709	3,688	2,555
Deposits	0	0	0	0
Mortgage Originations | Intersegment Eliminations
Summary of Operations
Total net interest income and noninterest income	(1)	3	1	9
Mortgage Servicing
Summary of Operations
Net interest income	10	3	23	10
Net gain on loan sales	0	0	0	0
Representation and warranty benefit	0	0	0	0
Other noninterest income (loss)	13	15	39	42
Total net interest income and noninterest income	23	18	62	52
(Provision) benefit for loan losses	0	0	0	0
Asset resolution	(2)		(6)	(12)
Depreciation and amortization expense	0	(1)	(2)	(2)
Other noninterest expense	(25)	(27)	(70)	(80)
Total noninterest expense	(27)	(28)	(78)	(94)
Income before income taxes	(4)	(10)	(16)	(42)
Provision for income taxes	0	0	0	0
Net income	(4)	(10)	(16)	(42)
Average balances
Loans held-for-sale	0	0	0	0
Loans with government guarantees	432	547	450	679
Loans held-for-investment	0	0	0	0
Total assets	623	860	676	1,004
Deposits	1,853	1,487	1,523	1,189
Mortgage Servicing | Intersegment Eliminations
Summary of Operations
Total net interest income and noninterest income	5	5	16	13
Community Banking
Summary of Operations
Net interest income	54	45	150	126
Net gain on loan sales	(1)	(4)	8	(13)
Representation and warranty benefit	0	0	0	0
Other noninterest income (loss)	8	11	21	19
Total net interest income and noninterest income	61	52	179	132
(Provision) benefit for loan losses	(7)	1	9	18
Asset resolution	0		0	(1)
Depreciation and amortization expense	(1)	(1)	(5)	(4)
Other noninterest expense	(43)	(39)	(131)	(116)
Total noninterest expense	(44)	(40)	(136)	(121)
Income before income taxes	10	13	52	29
Provision for income taxes	0	0	0	0
Net income	10	13	52	29
Average balances
Loans held-for-sale	16	21	83	36
Loans with government guarantees	0	0	0	0
Loans held-for-investment	5,843	5,348	5,689	4,786
Total assets	5,904	5,336	5,798	4,753
Deposits	7,273	6,773	7,080	6,602
Community Banking | Intersegment Eliminations
Summary of Operations
Total net interest income and noninterest income	0	(4)	(1)	(13)
Other
Summary of Operations
Net interest income	(5)	7	2	23
Net gain on loan sales	0	0	0	0
Representation and warranty benefit	0	0	0	0
Other noninterest income (loss)	31	2	41	(3)
Total net interest income and noninterest income	26	9	43	20
(Provision) benefit for loan losses	0	0	0	0
Asset resolution	0		0	0
Depreciation and amortization expense	(5)	(3)	(12)	(9)
Other noninterest expense	0	(3)	(6)	(7)
Total noninterest expense	(5)	(6)	(18)	(16)
Income before income taxes	21	3	25	4
Provision for income taxes	30	24	73	70
Net income	(9)	(21)	(48)	(66)
Average balances
Loans held-for-sale	0	0	0	0
Loans with government guarantees	0	0	0	0
Loans held-for-investment	0	60	0	96
Total assets	3,383	3,400	3,549	3,351
Deposits	0	0	0	0
Other | Intersegment Eliminations
Summary of Operations
Total net interest income and noninterest income	$ (4)	$ (4)	$ (16)	$ (9)