Condensed Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Contract drilling	$ 357,683	$ 339,636	$ 1,113,410	$ 1,140,568
Revenues related to reimbursable expenses	8,340	9,542	26,128	67,900
Total revenues	366,023	349,178	1,139,538	1,208,468
Operating expenses:
Contract drilling, excluding depreciation	198,072	186,654	597,812	597,831
Reimbursable expenses	8,220	7,965	25,488	51,283
Depreciation	83,281	86,473	262,492	295,729
General and administrative	17,806	15,237	54,299	48,774
Impairment of assets			71,268	678,145
Loss (gain) on disposition of assets	63	(1,222)	(2,085)	(2,265)
Total operating expenses	307,442	295,107	1,009,274	1,669,497
Operating income (loss)	58,581	54,071	130,264	(461,029)
Other income (expense):
Interest income	776	150	1,347	592
Interest expense, net of amounts capitalized	(28,562)	(19,032)	(83,409)	(68,704)
Loss on extinguishment of senior notes	(35,366)		(35,366)
Foreign currency transaction loss	(677)	(712)	(517)	(7,833)
Other, net	1,447	269	1,322	(11,199)
(Loss) income before income tax benefit (expense)	(3,801)	34,746	13,641	(548,173)
Income tax benefit (expense)	14,600	(20,819)	36,646	59,588
Net income (loss)	$ 10,799	$ 13,927	$ 50,287	$ (488,585)
Earnings (loss) per share, Basic and Diluted	$ 0.08	$ 0.10	$ 0.37	$ (3.56)
Weighted-average shares outstanding:
Shares of common stock	137,227	137,170	137,208	137,167
Dilutive potential shares of common stock	14	84	29
Total weighted-average shares outstanding	137,241	137,254	137,237	137,167