Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Revolving credit facility, including swing-line credit facility	$ 137,292us-gaap_LineOfCredit	$ 72,547us-gaap_LineOfCredit
1.00% Convertible senior notes due December 2020	225,370us-gaap_ConvertibleDebt	216,635us-gaap_ConvertibleDebt
Equipment financing notes	35us-gaap_OtherLongTermDebt	1,332us-gaap_OtherLongTermDebt
Total	612,697us-gaap_LongTermDebt	490,514us-gaap_LongTermDebt
Less: current portion	35us-gaap_LongTermDebtCurrent	1,289us-gaap_LongTermDebtCurrent
Total long-term debt, excluding current portion	612,662us-gaap_LongTermDebtNoncurrent	489,225us-gaap_LongTermDebtNoncurrent
Weighted-average combined rate	2.20%	2.50%
Senior subordinated notes due September 2018 [Member]
Debt Instrument [Line Items]
Senior notes		200,000
Notes stated interest percentage	8.25%
5.125% Senior notes due August 2022 [Member]
Debt Instrument [Line Items]
Senior notes	250,000
Notes stated interest percentage	5.125%
Convertible senior notes due December 2020 [Member]
Debt Instrument [Line Items]
1.00% Convertible senior notes due December 2020	225,370	216,635
Notes stated interest percentage	1.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility, including swing-line credit facility	$ 137,300

Including the current and noncurrent portions, carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

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- Definition

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

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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- Definition

The effective interest rate at the end of the reporting period.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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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.

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Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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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.

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