Debt, Non-Bank Debt (Details) - USD ($)	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014
Senior Notes [Member]
Non-Bank Debt (Textual)
Proceeds from issuance of senior long-term debt	$ 1,246,000,000
Debt issuance costs	12,000,000
Senior Notes [Member] \| Senior Notes Due in 2025 [Member]
Non-Bank Debt (Textual)
Face amount of long-term debt issuance	$ 600,000,000
Interest rate of notes in percentage	3.65%
Maturity date of long-term debt issuance	Mar. 15, 2025
Senior Notes [Member] \| Senior Notes Due in 2045 [Member]
Non-Bank Debt (Textual)
Face amount of long-term debt issuance	$ 650,000,000
Interest rate of notes in percentage	4.90%
Maturity date of long-term debt issuance	Mar. 15, 2045
Senior Notes [Member] \| Senior Notes Due In 2015 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage	4.50%
Debt repayments	$ 400,000,000
Senior Notes [Member] \| Senior Notes Due In 2014 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage		4.75%
Debt repayments		$ 200,000,000
Debentures [Member] \| Debenture Due In 2015 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage	8.75%
Debt repayments	$ 75,000,000

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- References

No definition available.

+ Details

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- Definition

The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

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Balance Type:	debit
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- Definition

The cash outflow attributable to repayments of borrowings not otherwise defined in the taxonomy (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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- Details

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- Details

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