Industry Segments Additional Details (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Industry Segments Details [Line Items]
Number of Reportable Segments			5
Number of Operating Segments			4
General and administrative expense	$ 31,232	$ 27,181	$ 59,688	$ 60,792
Depreciation, amortization, and accretion	28,620	33,538	58,098	67,145
Interest expense, net	14,328	14,335	28,095	28,974
Warrants fair value adjustment			(11,521)	0
Other Nonoperating Income (Expense)	(209)	(2,210)	(574)	(1,506)
Corporate Overhead [Member]
Industry Segments Details [Line Items]
General and administrative expense	12,051	8,021	21,606	17,950
Depreciation, amortization, and accretion	118	112	209	226
Interest expense, net	4,240	5,596	8,014	11,647
Warrants fair value adjustment	(5,545)	0	(11,521)	0
Other Nonoperating Income (Expense)	$ (305)	$ (2,450)	$ (733)	$ (2,740)
Total Offshore Division [Member]
Industry Segments Details [Line Items]
Number of Operating Segments			2