Reserves Related to Sales Allowances (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Valuation Allowance [Line Items]
Beginning balance	$ 1,669
Current provisions relating to sales in current year	4,412
Adjustments relating to prior years	(481)
Payments relating to sales in current year	(2,431)
Payments/returns relating to sales in prior years	(836)
Ending balance	2,333
Prompt pay and other discounts
Valuation Allowance [Line Items]
Beginning balance	388
Current provisions relating to sales in current year	1,776
Adjustments relating to prior years	13
Payments relating to sales in current year	(1,290)
Payments/returns relating to sales in prior years	(327)
Ending balance	560
Patient financial assistance
Valuation Allowance [Line Items]
Beginning balance	165
Current provisions relating to sales in current year	358
Adjustments relating to prior years	(55)
Payments relating to sales in current year	(231)
Payments/returns relating to sales in prior years	(47)
Ending balance	190
Government rebates and chargebacks
Valuation Allowance [Line Items]
Beginning balance	565
Current provisions relating to sales in current year	2,195
Adjustments relating to prior years	(298)
Payments relating to sales in current year	(910)
Payments/returns relating to sales in prior years	(271)
Ending balance	1,281
Returns
Valuation Allowance [Line Items]
Beginning balance	551
Current provisions relating to sales in current year	83
Adjustments relating to prior years	(141)
Payments/returns relating to sales in prior years	(191)
Ending balance	$ 302