Debt (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Short-term Debt [Table Text Block]

The following table presents the composition of our short-term borrowings portfolio.

	2016							2015
December 31, ($ in millions)	Unsecured		Secured (a)		Total			Unsecured		Secured (a)		Total
Demand notes	$	3,622	$	—	$	3,622		$	3,369	$	—	$	3,369
Federal Home Loan Bank	—		7,875		7,875			—		4,000		4,000
Financial instruments sold under agreements to repurchase	—		1,176		1,176			—		648		648
Other	—		—		—			84		—		84
Total short-term borrowings	$	3,622	$	9,051	$	12,673		$	3,453	$	4,648	$	8,101
Weighted average interest rate (b)					1.0		%					0.8		%

(a) Refer to the section below titled Long-term Debt for further details on assets restricted as collateral for payment of the related debt.

(b) Based on the debt outstanding and the interest rate at December 31 of each year.

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

The following tables present the composition of our long-term debt portfolio.

December 31, ($ in millions)	Amount			Interest rate	Weighted-average interest rate (a)		Due date range
2016
Unsecured debt
Fixed rate (b)	$	17,155
Variable rate	1
Trust preferred securities	2,568
Fair value adjustment (c)	326
Total unsecured debt	20,050			0.68–8.00%	5.36	%	2017–2049
Secured debt
Fixed rate	17,935
Variable rate	16,154
Fair value adjustment	(11		)
Total secured debt (d) (e) (f)	34,078			0.63–4.55%	1.53	%	2017–2035
Total long-term debt	$	54,128
2015
Unsecured debt
Fixed rate (b)	$	17,657
Variable rate	375
Trust preferred securities	2,600
Fair value adjustment (c)	334
Total unsecured debt	20,966			0.37–8.13%	5.40	%	2016–2049
Secured debt
Fixed rate	20,511
Variable rate	24,760
Fair value adjustment (c)	(3		)
Total secured debt (d) (e) (f)	45,268			0.48–4.06%	1.18	%	2016–2035
Total long-term debt	$	66,234

(a) Based on the debt outstanding and the interest rate at December 31 of each year excluding any impacts of interest rate hedges.

(b) Includes subordinated debt of $1.4 billion and $1.1 billion at December 31, 2016, and 2015, respectively.

(c) Represents the fair value adjustment associated with the application of hedge accounting on certain of our long-term debt positions. Refer to Note 22 to the Consolidated Financial Statements for additional information.

(d) Includes $13.3 billion and $20.3 billion of VIE secured debt at December 31, 2016, and 2015, respectively.

(e) Includes $14.8 billion and $19.9 billion of debt outstanding from the Automotive secured revolving credit facilities at December 31, 2016, and 2015, respectively.

(f) Includes advances from the Federal Home Loan Bank of Pittsburgh of $6.1 billion and $5.4 billion at December 31, 2016, and December 31, 2015, respectively.

Long-term Debt Portfolio [Table Text Block]

	2016							2015
December 31, ($ in millions)	Unsecured		Secured			Total		Unsecured		Secured			Total
Long-term debt
Due within one year	$	4,274	$	10,279		$	14,553	$	1,829	$	9,427		$	11,256
Due after one year	15,450		23,810			39,260		18,803		35,844			54,647
Fair value adjustment	326		(11		)	315		334		(3		)	331
Total long-term debt	$	20,050	$	34,078		$	54,128	$	20,966	$	45,268		$	66,234

Scheduled Remaining Maturity of Long-term Debt [Table Text Block]

The following table presents the scheduled remaining maturity of long-term debt at December 31, 2016, assuming no early redemptions will occur. The actual payment of secured debt may vary based on the payment activity of the related pledged assets.

($ in millions)	2017			2018			2019			2020			2021			2022 and thereafter			Fair value adjustment			Total
Unsecured
Long-term debt	$	4,365		$	3,700		$	1,681		$	2,212		$	638		$	8,454		$	326		$	21,376
Original issue discount	(91		)	(101		)	(39		)	(39		)	(43		)	(1,013		)	—			(1,326		)
Total unsecured	4,274			3,599			1,642			2,173			595			7,441			326			20,050
Secured
Long-term debt	10,279			8,156			7,334			4,248			2,481			1,591			(11		)	34,078
Total long-term debt	$	14,553		$	11,755		$	8,976		$	6,421		$	3,076		$	9,032		$	315		$	54,128

Pledged assets for the payment of the related secured borrowings and repurchase agreements [Table Text Block]

The following summarizes assets restricted as collateral for the payment of the related debt obligation primarily arising from securitization transactions accounted for as secured borrowings and repurchase agreements.

	2016					2015
December 31, ($ in millions)	Total			Ally Bank (a)		Total			Ally Bank (a)
Investment securities (b)	$	4,895		$	4,231	$	2,420		$	1,761
Mortgage assets held-for-investment and lending receivables	10,954			10,954		9,743			9,743
Consumer automotive finance receivables (b)	27,846			5,751		34,324			9,167
Commercial automotive finance receivables	19,487			19,280		19,623			19,177
Investment in operating leases, net	2,040			913		5,539			3,205
Total assets restricted as collateral (c) (d)	$	65,222		$	41,129	$	71,649		$	43,053
Secured debt	$	43,129	(e)	$	22,149	$	49,916	(e)	$	24,787

(a) Ally Bank is a component of the total column.

(b) A portion of the restricted investment securities and consumer automotive finance receivables are restricted under repurchase agreements. Refer to the section above titled Short-term Borrowings for information on the repurchase agreements.

(c) Ally Bank has an advance agreement with the FHLB, and had assets pledged to secure borrowings that were restricted as collateral to the FHLB totaling $19.0 billion and $14.9 billion at December 31, 2016, and December 31, 2015, respectively. These assets were composed primarily of consumer mortgage finance receivables and loans, net, and investment securities. Ally Bank has access to the Federal Reserve Bank Discount Window. Ally Bank had assets pledged and restricted as collateral to the Federal Reserve Bank totaling $2.4 billion and $2.9 billion at December 31, 2016, and December 31, 2015, respectively. These assets were composed of consumer automotive finance receivables and loans, net, and investment in operating leases, net. Availability under these programs is only for the operations of Ally Bank and cannot be used to fund the operations or liabilities of Ally or its subsidiaries.

(d) Excludes restricted cash and cash reserves for securitization trusts recorded within other assets on the Consolidated Balance Sheet. Refer to Note 14 to the Consolidated Financial Statements for additional information.

(e) Includes $9.1 billion and $4.6 billion of short-term borrowings at December 31, 2016, and December 31, 2015, respectively.

Schedule Of Committed Funding Facilities [Table Text Block]

Committed Funding Facilities

	Outstanding				Unused capacity (a)				Total capacity
December 31, ($ in millions)	2016		2015		2016		2015		2016		2015
Bank funding
Secured (b)	$	3,250	$	3,250	$	350	$	—	$	3,600	$	3,250
Parent funding
Secured	11,550		16,914		1,975		251		13,525		17,165
Unsecured (c)	—		—		1,250		—		1,250		—
Total committed facilities	$	14,800	$	20,164	$	3,575	$	251	$	18,375	$	20,415

(a) Funding from committed secured facilities is available on request in the event excess collateral resides in certain facilities or is available to the extent incremental collateral is available and contributed to the facilities.

(b) Excludes off-balance sheet credit facility amounts.

(c) This facility was fully drawn in January 2017. Refer to Note 32 for further information.