Income Taxes (Tables)
 6 Months Ended 12 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Schedule of Income Tax Disclosure [Line Items]    
Schedule of Components of Income Tax Expense (Benefit)
 
Three Months Ended June 30,
 
Six Months Ended June 30,
 
2016
2015
 
2016
2015
 
(Dollars in millions)
Provision for income taxes
$
22

$
28

 
$
43

$
46

Effective tax provision rate
32.7
%
37.2
%
 
33.4
%
37.0
%
  
Federal    
Schedule of Income Tax Disclosure [Line Items]    
Schedule of Components of Income Tax Expense (Benefit)  
Components of the provision (benefit) for income taxes consist of the following. 
 
For the Years Ended December 31,
 
2015
 
2014
 
2013
Current
(Dollars in millions)
Federal
$
2

 
$
2

 
$
—

State
—

 
(1
)
 
—

Total current income tax expense
2

 
1

 
—

Deferred
 
 
 
 
 
Federal
82

 
(35
)
 
(407
)
State
(2
)
 
—

 
(9
)
Total deferred income tax expense (benefit)
80

 
(35
)
 
(416
)
Total income tax expense (benefit)
$
82

 
$
(34
)
 
$
(416
)
Schedule of Effective Income Tax Rate Reconciliation  
The Company’s effective tax rate differs from the statutory federal tax rate. The following is a summary of such differences.
 
For the Years Ended December 31,
 
2015
 
2014
 
2013
 
(Dollars in millions)
Provision (benefit) at statutory federal income tax rate (35%)
$
84

 
$
(37
)
 
$
(52
)
(Decreases) increases resulting from:
 
 
 
 
 
Change in valuation allowance, federal and state
(6
)
 
8

 
(355
)
Residual tax effect associated with other comprehensive income
—

 
—

 
(6
)
State income tax (benefit), net of federal income tax effect
4

 
(9
)
 
(3
)
Warrant expense (income)
1

 
(2
)
 
—

Non-deductible compensation
1

 
1

 
—

Litigation settlement
—

 
4

 
—

Other
(2
)
 
1

 
—

Provision (benefit) for income taxes
$
82

 
$
(34
)
 
$
(416
)
Schedule of Net Deferred Tax Assets  
Temporary differences and carry forwards that give rise to deferred tax assets and liabilities are comprised of the following.
 
December 31,
 
2015
 
2014
 
(Dollars in millions)
Deferred tax assets
 
 
 
Tax loss carry forwards
$
258

 
$
292

Allowance for loan losses
89

 
140

Litigation settlement
31

 
30

Representation and warranty reserves
15

 
20

Alternative Minimum Tax credit carry forwards (indefinite carry forward period)
15

 
13

General business credit
1

 
—

Accrued compensation
9

 
—

Non-accrual interest revenue
3

 
6

Real Estate Mortgage Investment Conduits
—

 
5

Deferred interest
3

 
4

Other
9

 
7

Total
433

 
517

Valuation allowance
(22
)
 
(33
)
Total (net)
411

 
484

Deferred tax liabilities
 
 
 
Mortgage loan servicing rights
(19
)
 
(32
)
Mark-to-market adjustments
(17
)
 
(3
)
Commercial lease financing
(3
)
 
(3
)
Premises and equipment
(3
)
 
(2
)
State and local taxes
(5
)
 
(2
)
Total
(47
)
 
(42
)
Net deferred tax asset
$
364

 
$
442