Derivatives (Income Statement Impact) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)		$ 110		$ 169
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		54		46
Amount of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion)		0		0
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member] | Interest rate contracts [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	63	117	30	154
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member] | Interest rate contracts [Member] | Interest expense and other, net [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(221)	61	(411)	92
Amount of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion)	0	0	0	0
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member] | Diesel fuel swap [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)		(7)		15
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member] | Diesel fuel swap [Member] | Fuel expense (included in Costs of revenues, excluding depreciation and amortization) [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)		(7)		(46)
Designated Derivative Instruments [Member] | Derivatives in Cash Flow Hedging Relationships [Member] | Diesel fuel swap [Member] | Other (income) expense, net [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion)		0		0
Non-Designated Derivative Instruments [Member] | Interest rate contracts [Member] | Interest expense and other, net [Member]
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in Income on Derivatives		$ (11)		$ (29)