Shareholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended			139 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2013 Stock Option Plan 2013	May 01, 2013 Stock Option Plan 2013	Dec. 31, 2013 Employee Stock Option Plan	Dec. 31, 2013 Employee Stock Option Plan Upper end	Dec. 31, 2013 Employee Stock Purchase Plan	Dec. 31, 2012 Employee Stock Purchase Plan	Dec. 31, 2011 Employee Stock Purchase Plan	Dec. 31, 2013 Directors' Restricted Stock Plan 2008	May 31, 2008 Directors' Restricted Stock Plan 2008	Dec. 31, 2013 Non-Discretionary Plan	Dec. 31, 2013 Discretionary Plan	Feb. 24, 2014 Discretionary Plan Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for repurchase														40,000,000
Expected common stock shares issued and outstanding															200,000,000	190,000,000
Shares authorized for grant						3,000,000			9,305,452				200,000
Grants, maximum number of shares per person					100,000
Shares available for granting of awards					284,150							0
Award vesting period								5 years				1 year
Maximum contractual term							10 years
Purchase price percentage of fair market value									85.00%
Issuance of shares under stock purchase plan				8,139,481
Amount withheld employee stock purchase plan									$ 12,047,000
Fair value of annual grant per participant of restricted stock awards												200,000
Restricted shares granted												35,868
Weighted average fair value of award granted during the period									$ 9.43	$ 9.70	$ 11.70	$ 39.03
Total intrinsic value of options exercised	24,000,000	39,000,000	47,000,000
Total unrecognized share-based compensation cost	$ 82,000,000			$ 82,000,000
Unrecognized share-based compensation cost, weighted average period	2 years 10 months 25 days