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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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))

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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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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))

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Percentage of principal amount of debt redeemed.

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No definition available.

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- Definition

The cash inflow from borrowing by the entity from developers, builders, government agencies and municipalities for construction that are repaid in cash, generally on a straight-line basis over periods ranging from five to forty years.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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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)

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-Name Accounting Standards Codification

-Glossary Financing Activities

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

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- Definition

Mandatory date before maturity when outstanding debt instruments must be surrendered by their owners for purchase by the issuer, in CCYY-MM-DD format.

+ References

No definition available.

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Debt, Non-Bank Debt (Details) (USD $)	12 Months Ended			1 Months Ended
Debt, Non-Bank Debt (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 26, 2015
Senior Notes [Member] \| Senior Notes Due In 2015 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage	4.50%
Debt instrument, maturity date (month, day, year)	Dec. 31, 2015
Senior Notes [Member] \| Senior Notes Due In 2014 [Member]
Non-Bank Debt (Textual)
Debt repayments	200,000,000
Interest rate of notes in percentage	4.75%
Debt instrument, maturity date (month, day, year)	Dec. 31, 2014
Senior Notes [Member] \| Senior Notes Due In January 2013 [Member]
Non-Bank Debt (Textual)
Debt repayments		180,000,000
Interest rate of notes in percentage		6.70%
Senior Notes [Member] \| Senior Notes Due In June 2013 [Member]
Non-Bank Debt (Textual)
Debt repayments		300,000,000
Interest rate of notes in percentage		4.75%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds Series 1997 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage			5.60%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds Series 1998 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage			5.60%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds Series 1999 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage			5.70%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds Series 2001 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage			6.65%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds Series 1997A [Member]
Non-Bank Debt (Textual)
Debt repayments			4,000,000
Interest rate of notes in percentage			5.45%
Revenue Bonds [Member] \| Tax Exempt Industrial Revenue Bonds [Member]
Non-Bank Debt (Textual)
Debt repayments			108,000,000
Redemption value in percentage			100.00%
Revenue Bonds [Member] \| Gulf Opportunity Zone Revenue Bonds Series 2010 [Member]
Non-Bank Debt (Textual)
Interest rate of notes in percentage	4.00%		4.00%
Proceeds from advances for construction			300,000,000
Debt instrument, maturity date (month, day, year)	Dec. 01, 2040		Dec. 01, 2040
Debt instrument, mandatory tender date			Jun. 01, 2022
Notes [Member] \| Notes Due In 2012 [Member]
Non-Bank Debt (Textual)
Debt repayments			750,000,000
Interest rate of notes in percentage			6.875%
Subsequent Event [Member] \| Senior Notes [Member] \| Senior Notes Due In 2015 [Member]
Non-Bank Debt (Textual)
Debt repayments				$ 400,000,000
Interest rate of notes in percentage				4.50%