Regulatory Capital and Other Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2017

Regulatory Capital Requirements [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

The following table summarizes our capital ratios under the U.S. Basel III capital framework.

	September 30, 2017				December 31, 2016				Required minimum			Well-capitalized minimum
($ in millions)	Amount		Ratio		Amount		Ratio
Capital ratios
Common Equity Tier 1 (to risk-weighted assets)
Ally Financial Inc.	$	13,175	9.72	%	$	12,978	9.37	%	4.50	%		(a)
Ally Bank	16,454		15.39		17,888		16.70		4.50			6.50	%
Tier 1 (to risk-weighted assets)
Ally Financial Inc.	$	15,539	11.46	%	$	15,147	10.93	%	6.00	%		6.00	%
Ally Bank	16,454		15.39		17,888		16.70		6.00			8.00
Total (to risk-weighted assets)
Ally Financial Inc.	$	17,891	13.19	%	$	17,419	12.57	%	8.00	%		10.00	%
Ally Bank	17,215		16.10		18,458		17.24		8.00			10.00
Tier 1 leverage (to adjusted quarterly average assets) (b)
Ally Financial Inc.	$	15,539	9.51	%	$	15,147	9.54	%	4.00	%		(a)
Ally Bank	16,454		12.89		17,888		15.21		4.00		(c)	5.00	%

(a) Currently, there is no ratio component for determining whether a BHC is "well-capitalized."

(b) Federal regulatory reporting guidelines require the calculation of adjusted quarterly average assets using a daily average methodology.

(c) On August 22, 2017, the FRB lifted the capital, liquidity, and business plan commitments that Ally Bank made in connection with its application for membership in the Federal Reserve System, including the commitment to maintain a Tier 1 leverage ratio of at least15%. Ally Bank now manages its capital and liquidity subject to applicable regulatory requirements.

Schedule of Common Share Repurchase Activity [Table Text Block]

The following table presents information related to our common shares for each quarter since the commencement of our common share repurchase programs and initiation of a quarterly cash dividend on common stock.

($ in millions, except per share data; shares in thousands)	3rd quarter 2017		2nd quarter 2017		1st quarter 2017		4th quarter 2016		3rd quarter 2016
Common shares repurchased during period (a)
Approximate dollar value	$	190	$	204	$	169	$	167	$	159
Number of shares	8,507		10,485		8,097		8,745		8,298
Number of common shares outstanding
Beginning of period	452,292		462,193		467,000		475,470		483,753
End of period	443,796		452,292		462,193		467,000		475,470
Cash dividends declared per common share (b)	$	0.12	$	0.08	$	0.08	$	0.08	$	0.08

(a) Includes shares of common stock withheld to cover income taxes owed by participants in our share-based incentive plans.

(b) On October 10, 2017, the Ally Board of Directors declared a quarterly cash dividend payment of $0.12 per share on all common stock, payable on November 15, 2017. Refer to Note 26 for further information regarding this common share dividend.