Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Customer
Schedule Of Significant Accounting Policies [Line Items]
Restricted cash	7.2
Net product sales
Schedule Of Significant Accounting Policies [Line Items]
Number of customers accounted for net product sales	4
Net product sales | Customer One Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	22.00%
Net product sales | Customer Two Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	21.00%
Net product sales | Customer Three Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	17.00%
Net product sales | Customer Four Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	13.00%
Accounts receivable
Schedule Of Significant Accounting Policies [Line Items]
Number Of customers accounted for accounts receivable	4
Accounts receivable | Customer One Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	38.00%
Accounts receivable | Customer Two Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	13.00%
Accounts receivable | Customer Three Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	12.00%
Accounts receivable | Customer Four Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	10.00%
Letter of Credit
Schedule Of Significant Accounting Policies [Line Items]
Restricted cash	5.8