Condensed Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Contract drilling	$ 392,170	$ 357,409	$ 755,727	$ 800,932
Revenues related to reimbursable expenses	7,119	31,338	17,788	58,358
Total revenues	399,289	388,747	773,515	859,290
Operating expenses:
Contract drilling, excluding depreciation	196,217	198,336	399,740	411,177
Reimbursable expenses	6,790	16,527	17,268	43,318
Depreciation	85,982	105,016	179,211	209,256
General and administrative	19,010	18,139	36,493	33,537
Impairment of assets	71,268	678,145	71,268	678,145
Gain on disposition of assets	(802)	(747)	(2,148)	(1,043)
Total operating expenses	378,465	1,015,416	701,832	1,374,390
Operating income (loss)	20,824	(626,669)	71,683	(515,100)
Other income (expense):
Interest income	396	269	571	442
Interest expense, net of amounts capitalized	(27,251)	(24,156)	(54,847)	(49,672)
Foreign currency transaction (loss) gain	(927)	(3,513)	160	(7,121)
Other, net	(62)	(12,046)	(125)	(11,468)
(Loss) income before income tax benefit	(7,020)	(666,115)	17,442	(582,919)
Income tax benefit	22,969	76,178	22,046	80,407
Net income (loss)	$ 15,949	$ (589,937)	$ 39,488	$ (502,512)
Earnings (loss) per share, Basic and Diluted	$ 0.12	$ (4.30)	$ 0.29	$ (3.66)
Weighted-average shares outstanding:
Shares of common stock	137,224	137,170	137,199	137,166
Dilutive potential shares of common stock	3		36
Total weighted-average shares outstanding	137,227	137,170	137,235	137,166