Accumulated Other Comprehensive Income - Narrative (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Preferred stock cash dividend	$ 31,000,000us-gaap_DividendsPreferredStockCash	$ 6,000,000us-gaap_DividendsPreferredStockCash
Cash dividends declared (in dollars per share)	$ 0.3	$ 0.26
Common stock dividends	(124,000,000)us-gaap_DividendsCommonStockCash	(112,000,000)us-gaap_DividendsCommonStockCash
March 2015 Share Repurchase
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase	1,800,000,000
Stock Repurchased During Period, Shares	0
March 2014 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased During Period, Shares	6,300,000
Treasury Stock Acquired, Average Cost Per Share	$ 74.88
Stock Repurchased During Period, Value	470,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	0
Series C Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 1,313	$ 1,313
Preferred stock cash dividend	6,000,000	6,000,000
Series C Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 0.33	$ 0.33
Series D Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 1,475	$ 0
Preferred stock cash dividend	11,000,000
Series D Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 0.37
Series E Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 1,833	$ 0
Preferred stock cash dividend	14,000,000
Series E Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 0.46
Retained Earnings
Equity, Class of Treasury Stock [Line Items]
Preferred stock cash dividend	31,000,000	6,000,000
Common stock dividends	$ (124,000,000)	$ (112,000,000)

Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

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- Definition

Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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Aggregate dividends declared during the period for each share of preferred stock outstanding.

+ References

No definition available.

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

-Article 5

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Amount of stock repurchase plan authorized.

+ References

No definition available.

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- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

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- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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