Bank holding companies with assets greater than $50 billion must develop and maintain a capital plan annually.

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Percentage Of Tier One Common Risk Based Capital to Risk Weighted Assets

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Capital plan must include discussion of how bank holding companies will keep Tier 1 common ratio above 5 percent under certain conditions.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets in accordance with CLMA requirements for Ally Bank.

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Tier One Common Risk Based Capital

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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Regulatory Capital (Schedule Of Regulatory Capital Amount And Ratios) (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Parent Company [Member]	Dec. 31, 2012 Parent Company [Member]	Jun. 30, 2013 Parent Company [Member] Minimum [Member]	Jun. 30, 2013 Parent Company [Member] Maximum [Member]	Jun. 30, 2013 Ally Bank [Member]	Dec. 31, 2012 Ally Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
assets greater than $50 billion	$ 50,000,000,000
Tier 1 common ratio above 5 percent	5.00%
Tier 1 (to risk-weighted assets), Amount		19,659,000,000	20,232,000,000			14,682,000,000	14,136,000,000
Tier 1 (to risk-weighted assets), Ratio		15.45%	13.13%			17.59%	16.26%
Tier 1 (to risk-weighted assets), Required minimum		4.00%				4.00%
Tier 1 (to risk-weighted assets), Well-capitalized minimum		6.00%				6.00%
Total (to risk-weighted assets), Amount		20,968,000,000	21,669,000,000			15,368,000,000	14,827,000,000
Total (to risk-weighted assets), Ratio		16.48%	14.07%			18.42%	17.06%
Total (to risk-weighted assets), Required minimum		8.00%				8.00%
Total (to risk-weighted assets), Well-capitalized minimum		10.00%				10.00%
Tier 1 leverage (to adjusted average assets), Amount		19,659,000,000	20,232,000,000			14,682,000,000	14,136,000,000
Tier 1 leverage (to adjusted average assets), Ratio		13.16%	11.16%			15.93%	15.30%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets				3.00%	4.00%
Tier 1 Leverage To Average Assets For Ally Bank						15.00%
Tier 1 leverage (to adjusted average assets), Well-capitalized minimum						5.00%
Tier 1 common (to risk-weighted assets), Amount		$ 10,175,000,000	$ 10,749,000,000
Tier 1 common (to risk-weighted assets), Ratio		8.00%	6.98%