Interest Expense (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Debt Disclosure [Abstract]
Interest expense		$ 154	$ 227	[1]	$ 207	[1]
Amortization of debt premiums/discounts, net	[2]	(1)	(13)	[1]	(16)	[1]
Amortization of deferred financing costs		(6)	(8)	[1]	(8)	[1]
Non-cash losses on debt extinguishments	[1]		(11)		(2)
Change in accrued interest		(3)	12	[1]	1	[1]
Interest paid	[3]	$ 144	$ 207	[1]	$ 182	[1]

[1] Interest expense and interest paid for 2015 and 2014 include cash prepayment premiums of approximately $30 million and $2 million, respectively.

[2] Primarily represents the amortization of the debt discount on our Debentures, which is considered non-cash interest expense.

[3] Does not include capitalized interest of $3 million, $5 million and $7 million for 2016, 2015 and 2014, respectively.