Earnings (loss) Per Share - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Computation Of Earnings Per Share Line Items
Common stock issued in exchange for convertible notes	22	22
Aggregate principal amount of senior convertible notes exchanged		$ 189
6% Convertible Senior Notes
Computation Of Earnings Per Share Line Items
Aggregate principal amount of senior convertible notes exchanged	$ 189	$ 189
Debt instrument effective interest rate	6.00%	6.00%
Due date of debt instrument	2029	2029