Debt (Schedule Of Obligations Under Debt Arrangements) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Senior secured credit facility	$ 585,200	$ 550,400
Senior unsecured notes	1,100,000	1,050,639
Total long-term debt	1,685,200	1,601,039
7.875% Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes	$ 0	$ 350,639
Senior unsecured notes, stated rate	7.875%	7.875%
Senior unsecured notes, unamortized premium	$ 0	$ 639
Six Percentage Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes	$ 400,000	$ 0
Senior unsecured notes, stated rate	6.00%	6.00%
Five Point Seventy Five Percentage Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes	$ 350,000	$ 350,000
Senior unsecured notes, stated rate	5.75%	5.75%
Five Point Six Two Five Percentage Senior Unsecured Notes [Member] [Domain]
Debt Instrument [Line Items]
Senior unsecured notes	$ 350,000	$ 350,000
Senior unsecured notes, stated rate	5.625%	5.625%

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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

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Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

+ References

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Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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