Additional Long Term Debt Textuals.

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- Definition

Financing fees paid.

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- Definition

Long term debt.

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- Definition

Loss on tender and redemption on the notes.

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- Definition

Quarterly Commitment Fee Of Credit Facility.

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Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

+ 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 Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 4

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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 21
-Paragraph 16, 20

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- Definition

Interest rate stated in the contractual debt agreement.

+ 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

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- Definition

Interest and debt related expenses associated with nonoperating financing activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 34
-Paragraph 21

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- Definition

Description of the fees for amounts available, but unused under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

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- Definition

Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter).

+ References

+ Details

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- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

+ References

+ Details

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- Definition

The effective interest during the reporting period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Long Term Debt (Details Textual) (USD $)	6 Months Ended			3 Months Ended	6 Months Ended			6 Months Ended			6 Months Ended					6 Months Ended
Long Term Debt (Details Textual) (USD $)	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 8.125% Senior Unsecured Notes due 2016 [Member]	Jun. 30, 2011 8.125% Senior Unsecured Notes due 2016 [Member]	Jun. 30, 2010 8.125% Senior Unsecured Notes due 2016 [Member]	Dec. 31, 2010 8.125% Senior Unsecured Notes due 2016 [Member]	Jun. 30, 2011 7.75% Senior Unsecured Notes due 2018 [Member]	Jun. 30, 2010 7.75% Senior Unsecured Notes due 2018 [Member]	Dec. 31, 2010 7.75% Senior Unsecured Notes due 2018 [Member]	Jun. 30, 2011 Credit Facility [Member]	Jun. 30, 2010 Credit Facility [Member]	Jun. 30, 2011 Letter of Credit [Member]	Jun. 10, 2011 Letter of Credit [Member]	Jun. 10, 2011 Swing Line Loan [Member]	Jun. 30, 2011 Amended Credit Agreement [Member]	Jun. 30, 2011 Senior Notes [Member]	Jun. 30, 2011 7.125% senior unsecured notes due 2021 [Member]	Apr. 05, 2011 7.125% senior unsecured notes due 2021 [Member]	Jun. 10, 2011 Existing Borrowing Capacity [Member]	Jun. 10, 2011 New Borrowing Capacity [Member]
Additional Long Term Debt (Textuals) [Abstract]
Senior secured revolving credit facility														$ 100,000,000	$ 75,000,000					$ 550,000,000	$ 700,000,000
Interest and financing cost					7,664,000	13,902,000		9,941,000	9,941,000		2,767,000	3,535,000						6,326,000
Debt instrument, covenant description																	Ratio of EBITDA to fixed charges is at least 1.75x
Aggregate principal amount outstanding	609,525,000		582,736,000				332,665,000	249,525,000		249,525,000								360,000,000
Unamortized portion of debt issue costs				4,185,000	4,185,000			3,763,000			11,207,000							7,745,000
Line of Credit Facility, Expiration Date													10/18/2012			6/10/2016
Conditions of determining interest rate																Interest is determined, at our election, by reference to (a) the British Bankers Association LIBOR rate, or LIBOR, plus an applicable rate between 2.0% and 3.25% per annum or (b) the highest of (1) the federal funds rate plus 0.50%, (2) the prime rate and (3) LIBOR plus 1.0%, plus, in each case, an applicable rate between 1.0% and 2.25% per annum
Quarterly commitment fee																Determined by reference to an applicable rate between 0.375% and 0.5% per annum
Interest rate stated percentage				8.125%	8.125%			7.75%										7.125%
Public offering closed in aggregate principle amount																			360,000,000
Loss on tender and redemption on the notes				18,233,000
Financing fees paid																$ 7,813,000
Long Term Debt (Textuals) [Abstract]
Effective average interest rate on borrowings under the credit facility	2.40%	1.80%
Quarterly commitment fee of the credit facility	0.375% on the unused portion	0.25% on the unused portion