Segment Information (Schedule of Revenues from External Customers and Long-Lived Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 2013 Drilling Services Segment [Member] drilling_rigs	Dec. 31, 2012 Drilling Services Segment [Member]	Oct. 19, 2012 Drilling Services Segment [Member] drilling_rigs	Dec. 31, 2011 Drilling Services Segment [Member]	Dec. 31, 2010 Drilling Services Segment [Member]	Dec. 31, 2012 Drilling Services Segment [Member] Colombia [Member]	Dec. 31, 2011 Drilling Services Segment [Member] Colombia [Member]	Dec. 31, 2010 Drilling Services Segment [Member] Colombia [Member]	Jan. 31, 2013 Drilling Services Segment [Member] Colombia [Member] drilling_rigs	Dec. 31, 2012 Drilling Services Segment [Member] Colombia [Member] Drilling rigs and equipment [Member] drilling_rigs	Dec. 31, 2011 Drilling Services Segment [Member] Colombia [Member] Drilling rigs and equipment [Member] drilling_rigs	Dec. 31, 2010 Drilling Services Segment [Member] Colombia [Member] Drilling rigs and equipment [Member] drilling_rigs	Dec. 31, 2012 Drilling Services Segment [Member] Colombia [Member] Assets Leased From Others [Member] drilling_rigs	Dec. 31, 2011 Drilling Services Segment [Member] Colombia [Member] Assets Leased From Others [Member] drilling_rigs	Dec. 31, 2010 Drilling Services Segment [Member] Colombia [Member] Assets Leased From Others [Member] drilling_rigs
Revenues from External Customers and Long-Lived Assets [Line Items]
Indentifiable assets	$ 1,339,776				$ 1,172,754				$ 1,339,776	$ 1,172,754	$ 841,343		$ 867,526		$ 667,588	$ 542,242	$ 148,567	$ 151,448	$ 157,509
Revenues	$ 227,868	$ 229,773	$ 229,824	$ 231,978	$ 203,656	$ 187,651	$ 171,285	$ 153,349	$ 919,443	$ 715,941	$ 487,210						$ 95,338	$ 109,539	$ 86,432
Drilling Rigs												70		70						8	5	5	5	3	3	3