Discontinued Operations - Schedule of Operation from Discontinued Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Operating revenues
Operating revenues from discontinued operations	$ 1,034,458	$ 1,696,147
Income from discontinued operations
Income from discontinued operations before income taxes	216,391	379,591
Income tax provision	(55,889)	(75,489)
Net income from discontinued operations, net of tax	160,502	304,102
Contract Drilling Services [Member]
Operating revenues
Operating revenues from discontinued operations	993,253	1,615,325
Reimbursables [Member]
Operating revenues
Operating revenues from discontinued operations	21,899	45,582
Labor Contract Drilling Services [Member]
Operating revenues
Operating revenues from discontinued operations	19,304	35,146
Other [Member]
Operating revenues
Operating revenues from discontinued operations	$ 2	$ 94