Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Contract drilling	$ 2,360,184	$ 2,737,126	$ 2,843,584
Revenues related to reimbursable expenses	59,209	77,545	76,837
Total revenues	2,419,393	2,814,671	2,920,421
Operating expenses:
Contract drilling, excluding depreciation	1,227,864	1,523,623	1,572,525
Reimbursable expenses	58,050	76,091	74,967
Depreciation	493,162	456,483	388,092
General and administrative	66,462	81,832	64,788
Impairment of assets	860,441	109,462
Bad debt expense			22,513
Restructuring and separation costs	9,778
Gain on disposition of assets	(2,290)	(5,382)	(4,070)
Total operating expenses	2,713,467	2,242,109	2,118,815
Operating (loss) income	(294,074)	572,562	801,606
Other income (expense):
Interest income	3,322	801	701
Interest expense, net of amounts capitalized	(93,934)	(62,053)	(24,843)
Foreign currency transaction gain (loss)	2,465	3,199	(4,915)
Other, net	873	682	1,691
(Loss) income before income tax benefit (expense)	(381,348)	515,191	774,240
Income tax benefit (expense)	107,063	(128,180)	(225,554)
Net (loss) income	$ (274,285)	$ 387,011	$ 548,686
(Loss) earnings per share:
Basic	$ (2.00)	$ 2.82	$ 3.95
Diluted	$ (2.00)	$ 2.81	$ 3.95
Weighted-average shares outstanding:
Shares of common stock	137,157	137,473	139,035
Dilutive potential shares of common stock		50	29
Total weighted-average shares outstanding	137,157	137,523	139,064
Cash dividends declared per share of common stock	$ 0.50	$ 3.50	$ 3.50