Impairment of Long-Lived Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	$ 675	$ 1,064
Impairment of proved property and equipment
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	675
Impairment of leaseholds and the write-off of other non-core assets
Impairment of Long-Lived Assets (Textual) [Abstract]
Impairment and abandonment of equipment and properties	$ 0	$ 25