Fair-Value Measurements (Schedule of Fair Value of Derivative Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ (4,261)	$ (4,718)
Total derivatives	(4,261)	(4,718)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	(4,261)	(4,718)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ (4,300)