Impairment of Long-Lived Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	$ 1,064	$ 305
Impairment of proved property and equipment
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	1,039	301
Impairment of leaseholds
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	$ 25	$ 4