Segment Information (Schedule of Revenues from External Customers and Long-Lived Assets) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($) drilling_rigs	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) drilling_rigs	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) drilling_rigs	Dec. 31, 2014 USD ($) drilling_rigs	Dec. 31, 2013 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 829,776				$ 1,171,589				$ 829,776	$ 1,171,589	$ 1,229,623
Revenues	104,473	$ 107,480	$ 135,011	$ 193,814	283,110	$ 273,267	$ 259,812	$ 239,034	540,778	1,055,223	960,186
Drilling Services Segment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 518,208				702,987				$ 518,208	702,987	785,119
Drilling Rigs | drilling_rigs	31								31
Drilling Services Segment [Member] | Colombia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 54,590				$ 142,321				$ 54,590	142,321	150,719
Revenues									$ 43,878	$ 104,520	$ 115,631
Drilling Rigs | drilling_rigs	8								8
Drilling Services Segment [Member] | Colombia [Member] | Assets Leased From Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Drilling Rigs | drilling_rigs	3				3				3	3