Components of Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal income tax benefit:
Current	$ (42)	$ (24,777)	$ (42,020)
Deferred	(335,106)	(134,592)	(83,812)
Federal income tax benefit, Total	(335,148)	(159,369)	(125,832)
State income tax expense (benefit):
Current	(215)	(257)	(3,480)
Deferred	4,511	(14,163)	(12,433)
State and Local Income Tax Expense (Benefit), Continuing Operations, Total	4,296	(14,420)	(15,913)
Foreign income tax expense (benefit):
Current	(3,108)	(368)	(2,590)
Deferred	249	(3,405)	(3,628)
Foreign Income Tax Expense (Benefit), Continuing Operations, Total	(2,859)	(3,773)	(6,218)
Total income tax benefit:
Current	(3,365)	(25,402)	(48,090)
Deferred	(330,346)	(152,160)	(99,873)
Total income tax benefit:	$ (333,711)	$ (177,562)	$ (147,963)

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 6.I.7)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319