Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		$ 761,920	$ 631,355	$ 1,496,114	$ 1,193,905
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		10,884	(26,187)	10,827	(90,515)
Earnings (losses) from unconsolidated affiliates		(1)		1	2
Investment income (loss)		(3,164)	(886)	(2,699)	(165)
Interest expense		(60,592)	(54,688)	(121,978)	(111,206)
Other, net		(77,601)	(10,104)	(91,690)	(23,614)
Income (loss) from continuing operations before income taxes		(171,937)	(134,972)	(291,979)	(308,209)
ASSETS
Total assets (1)	[1]	8,300,288		8,300,288		$ 8,401,984
U.S. Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		264,395	187,344	505,397	349,278
Canada Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		17,442	17,121	49,329	44,929
International Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		377,986	380,338	746,831	718,561
Drilling Solutions
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		(59,859)	31,829	122,507	59,194
Rig Technologies
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		81,321	61,185	145,990	105,261
Operating segment
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		10,884	(26,187)	10,827	(90,515)
Operating segment | U.S. Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		264,395	187,344	505,397	349,278
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		(13,107)	(56,079)	(32,853)	(119,261)
ASSETS
Total assets (1)		3,116,162		3,116,162		3,203,560
Operating segment | Canada Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		17,442	17,121	49,329	44,929
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		(4,608)	(5,014)	(5,200)	(9,025)
ASSETS
Total assets (1)		317,872		317,872		347,773
Operating segment | International Drilling
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		377,986	380,338	746,831	718,561
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		24,486	36,174	49,022	48,148
ASSETS
Total assets (1)		3,312,637		3,312,637		3,540,829
Operating segment | Drilling Solutions
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		59,859	31,829	122,507	59,194
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		7,546	3,772	16,267	2,794
ASSETS
Total assets (1)		201,445		201,445		182,162
Operating segment | Rig Technologies
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		81,321	61,185	145,990	105,261
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		(3,433)	(5,040)	(16,409)	(13,171)
ASSETS
Total assets (1)		467,519		467,519		459,665
Other reconciling items (3)
Operating revenues and earnings (losses) from unconsolidated affiliates:
Revenue		39,083	46,462	73,940	83,318
Reconciliation of segment adjusted operating income (loss) to net income (loss) from continuing operations before income taxes:
Adjusted income (loss) derived from operating activities		(41,463)	$ (43,107)	(86,440)	$ (82,711)
ASSETS
Total assets (1)		$ 884,653		$ 884,653		$ 667,995

[1] The condensed consolidated balance sheet as of June 30, 2018 and December 31, 2017 include assets and liabilities of variable interest entities. See Note 3—Joint Ventures for additional information.