Regulatory Matters (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Tangible Capital
Tangible capital (to tangible assets), actual amount	$ 1,561	$ 1,505
Tangible capital (to tangible assets), actual ratio	7.86%	8.29%
Tier One Leverage Capital
Tier 1 capital actual amount	$ 1,561	$ 1,505
Tier 1 capital (to adjusted tangible assets), actual ratio	7.86%	8.29%
Tier 1 capital, for capital adequacy purposes amount	$ 795	$ 726
Tier 1 capital (to adjusted tangible assets), for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital capitalized under prompt corrective action provision amount	$ 994	$ 908
Tier 1 capital (to adjusted tangible assets), capitalized under prompt corrective action provision ratio	5.00%	5.00%
Common Equity Tier 1 Capital
Common equity Tier 1 capital (to RWA), actual amount	$ 1,321	$ 1,265
Common equity Tier 1 capital (to RWA), actual ratio	9.08%	10.54%
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, amount	$ 655	$ 540
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, ratio	4.50%	4.50%
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, amount	$ 946	$ 780
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Tier One Risk Based Capital [Abstract]
Tier 1 capital, actual amount	$ 1,561	$ 1,505
Tier 1 capital (to risk-weighted assets), actual ratio	10.73%	12.54%
Tier 1 capital, for capital adequacy purposes amount	$ 873	$ 720
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	6.00%	6.00%
Tier 1 capital, capitalized under prompt corrective action provision amount	$ 1,164	$ 960
Tier 1 capital (to risk-weighted assets), capitalized under prompt corrective action provision ratio	8.00%	8.00%
Capital [Abstract]
Total capital, actual amount	$ 1,674	$ 1,637
Total capital (to risk-weighted assets), actual ratio	11.51%	13.63%
Total capital, for capital adequacy purposes amount	$ 1,164	$ 960
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	8.00%	8.00%
Total capital, capitalized under prompt corrective action provisions amount	$ 1,455	$ 1,201
Total capital (to risk-weighted assets), capitalized under prompt corrective action provisions ratio	10.00%	10.00%
Bank
Tangible Capital
Tangible capital (to tangible assets), actual amount	$ 1,632	$ 1,574
Tangible capital (to tangible assets), actual ratio	8.32%	8.67%
Tier One Leverage Capital
Tier 1 capital actual amount	$ 1,633	$ 1,574
Tier 1 capital (to adjusted tangible assets), actual ratio	8.32%	8.67%
Tier 1 capital, for capital adequacy purposes amount	$ 785	$ 726
Tier 1 capital (to adjusted tangible assets), for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital capitalized under prompt corrective action provision amount	$ 981	$ 908
Tier 1 capital (to adjusted tangible assets), capitalized under prompt corrective action provision ratio	5.00%	5.00%
Common Equity Tier 1 Capital
Common equity Tier 1 capital (to RWA), actual amount	$ 1,633	$ 1,574
Common equity Tier 1 capital (to RWA), actual ratio	11.23%	13.12%
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, amount	$ 654	$ 540
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, ratio	4.50%	4.50%
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, amount	$ 945	$ 780
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Tier One Risk Based Capital [Abstract]
Tier 1 capital, actual amount	$ 1,633	$ 1,574
Tier 1 capital (to risk-weighted assets), actual ratio	11.23%	13.12%
Tier 1 capital, for capital adequacy purposes amount	$ 872	$ 720
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	6.00%	6.00%
Tier 1 capital, capitalized under prompt corrective action provision amount	$ 1,163	$ 960
Tier 1 capital (to risk-weighted assets), capitalized under prompt corrective action provision ratio	8.00%	8.00%
Capital [Abstract]
Total capital, actual amount	$ 1,745	$ 1,705
Total capital (to risk-weighted assets), actual ratio	12.00%	14.21%
Total capital, for capital adequacy purposes amount	$ 1,163	$ 960
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	8.00%	8.00%
Total capital, capitalized under prompt corrective action provisions amount	$ 1,454	$ 1,200
Total capital (to risk-weighted assets), capitalized under prompt corrective action provisions ratio	10.00%	10.00%

Common Equity Tier 1 Capital [Abstract]

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Tier 1 Common Equity as defined in the regulations.

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The minimum amount of Tier 1 Common Equity required for capital adequacy purposes under the regulatory framework for prompt corrective actions.

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The minimum amount of Tier One Common Equity Required for Capital Adequacy (Tier 1 Common Equity divided by Risk Weighted Assets) as defined in the regulations.

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The amount of Tier 1 Common Equity required to be well capitalized under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Common Equity required to be well capitalized (Tier 1 Common Equity divided by risk weighted assets) as defined in the regulatory framework for prompt corrective action.

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Tier One Common Equity divided by Risk Weighted Assets as defined in the regulations.

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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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 amount of Total Capital required to be categorized as well as capitalized 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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Tangible capital as defined in the regulations (generally includes outstanding stock plus retained earnings) for banking institutions subject to Office of Thrift Supervision (OTS) capital requirements.

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Tangible Capital divided by Tangible 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 required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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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 under the regulatory framework for prompt corrective action.

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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 amount of Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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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 amount of Tier 1 Risk Based Capital required to be categorized as well capitalized 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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