Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net loss	$ (6,576)	$ (7,796)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	781	342
Accretion of premium on marketable investment securities	912	502
Shares issued for payment of services	0	549
Non-cash interest expense	2,270	3,159
Non-cash royalties	(10,347)	(9,810)
Compensation expense on share-based awards	4,078	2,956
Realized gain on sale of marketable investment securities	(7)	0
(Increase) decrease in operating assets:
Accounts receivable	8,339	2,310
Inventory	(2,182)	(85)
Prepaid expenses, other current assets and other assets	(887)	2,261
(Decrease) increase in operating liabilities:
Accounts payable and accrued expenses	(4,743)	(3,628)
Other liabilities	1,692	(79)
Net cash used in operating activities	(6,670)	(9,319)
Cash flows from investing activities:
Sales of marketable investment securities	3,426	2,085
Maturities of marketable investment securities	34,436	25,922
Purchases of marketable investment securities	(31,820)	(16,339)
Acquisitions of property and equipment	(318)	(288)
Net cash provided by investing activities	5,724	11,380
Cash flows from financing activities:
Net proceeds from the exercise of stock options	4,868	396
Shares withheld for the payment of taxes	(1,898)	(574)
Net cash provided by (used in) financing activities	2,970	(178)
Effect of exchange rate changes on cash	(2)	2
Net increase in cash and cash equivalents	2,022	1,885
Cash and cash equivalents at beginning of period	51,204	17,471
Cash and cash equivalents at end of period	53,226	19,356
Supplemental Disclosures of Cash Flow Information
Cash paid for interest	235	235
Cash paid for income taxes	8	0
Supplemental Disclosure of Non-cash Investing and Financing Activities
6.1 million shares of NPS common stock issued in connection with the Takeda Termination and Transition agreement	0	55,403
Unrealized (loss) gain on marketable investment securities	(7)	9
Accrued acquisition of property and equipment	65	3
Noncash reductions of debt	$ 8,676	$ 6,278