Consolidated Statement of Cash Flows Supplemental Disclosures ( Non-cash investing and financing activities) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Supplemental Cash Flow Elements [Abstract]
Non-cash additions for purchases of property and equipment	$ 25,114	$ 13,740
Net capital lease obligation	9,386	0
Distribution to non-controlling interest	4,167	0
Asset retirement obligation additions to property and equipment	361	1,066
Deferred compensation distribution denominated in shares	$ 617	$ 621