Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Segment	Sep. 30, 2011	Dec. 31, 2011
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash, cash equivalents, and investments in marketable securities	$ 354,300,000		$ 354,300,000
Indebtedness	152,000,000		152,000,000
Outstanding convertible subordinated notes	0		0		214,955,000
Senior secured notes, issued	125,000,000
Principal amount of the convertible subordinated notes , retired amount	215,000,000		215,000,000
Number of business segments			1
Allowance for doubtful accounts	0		0		0
Effective income tax rate	32.00%	32.00%	32.00%	32.00%
Senior Notes [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Senior secured notes, interest rate	12.00%		12.00%
Maximum [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Contingent payment related to royalty obligation	$ 7,000,000		$ 7,000,000