Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
8.25% Senior subordinated notes due September 2018	$ 200,000	$ 200,000
Revolving credit facility, including swing-line credit facility	151,400	152,000
Equipment financing notes	2,589	2,819
Total	353,989	354,819
Less: current portion	1,582	1,467
Total long-term debt, excluding current portion	352,407	353,352
Weighted-average combined rate	2.40%	2.20%
Senior Subordinated Notes Due September 2018 [Member]
Debt Instrument [Line Items]
8.25% Senior subordinated notes due September 2018	$ 200,000
Senior subordinated notes stated interest percentage	8.25%