Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Senior subordinated notes due September 2018 [Member]	Dec. 31, 2013 Convertible senior notes due December 2020 [Member]	Nov. 21, 2013 Convertible senior notes due December 2020 [Member]
Debt Instrument [Line Items]
8.25% Senior subordinated notes due September 2018	$ 200,000	$ 200,000	$ 200,000
1.00% Convertible senior notes due December 2020	216,635			216,635	215,800
Revolving credit facility, including swing-line credit facility	72,547	152,000
Equipment financing notes	1,332	2,819
Total	490,514	354,819
Less: current portion	1,289	1,467
Total long-term debt, excluding current portion	$ 489,225	$ 353,352
Weighted-average combined rate	2.50%	2.20%
Notes stated interest percentage			8.25%	1.00%