Segment Information (Schedule of Revenues from External Customers and Long-Lived Assets) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) drilling_rigs	Sep. 30, 2015 USD ($) drilling_rigs	Sep. 30, 2016 USD ($) drilling_rigs	Sep. 30, 2015 USD ($) drilling_rigs	Dec. 31, 2015 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 722,797		$ 722,797		$ 821,993
Revenues	68,353	$ 107,480	205,595	$ 436,305
Drilling Services Segment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 463,621	571,203	$ 463,621	571,203
Drilling Rigs | drilling_rigs	31		31
Drilling Services Segment [Member] | Colombia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 37,444	57,777	$ 37,444	57,777
Revenues	$ 622	$ 2,670	$ 1,979	$ 36,709
Drilling Rigs | drilling_rigs	8	8	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