Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net loss	$ (8,705)	$ (13,504)	$ (18,735)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,335	2,630	1,083
Accretion of premium (discount) on marketable investment securities	3,206	2,956	2,005
Shares issued for payment of services	0	549	0
Non-cash interest expense	7,278	10,982	17,239
Non-cash royalties	(40,304)	(39,804)	(55,993)
Realized gain on sale of marketable investment securities	(12)	(4)	(4)
Loss on disposal of equipment	0	41	0
Compensation expense on share-based awards	15,003	9,437	7,548
(Increase) decrease in operating assets:
Accounts receivable	(7,713)	(11,324)	(16,010)
Inventory	(898)	4,265	0
Prepaid expenses, other current assets and other assets	138	(466)	1,803
(Decrease) increase in operating liabilities:
Accounts payable and accrued expenses	6,839	11,257	1,321
Other liabilities	5,123	(1,331)	(1,249)
Net cash used in operating activities	(16,710)	(24,316)	(60,992)
Cash flows from investing activities:
Sales of marketable investment securities	11,209	11,850	7,628
Maturities of marketable investment securities	123,458	96,021	111,879
Purchases of marketable investment securities	(107,276)	(156,842)	(124,809)
Acquisitions of property and equipment	(3,093)	(1,142)	(1,187)
Net cash provided by (used in) investing activities	24,298	(50,113)	(6,489)
Cash flows from financing activities:
Excess tax benefit from stock options	312	178	0
Net proceeds from the sale of common stock and exercise of stock options	8,118	107,940	2,561
Net cash provided by financing activities	8,430	108,118	2,561
Effect of exchange rate changes on cash	(1,657)	44	(10)
Net increase (decrease) in cash and cash equivalents	14,361	33,733	(64,930)
Cash and cash equivalents at beginning of period	51,204	17,471	82,401
Cash and cash equivalents at end of period	65,565	51,204	17,471
Supplemental Disclosures of Cash Flow Information
Cash paid for interest	256	952	954
Cash paid for income taxes	270	4	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, see note 10	0	55,403	0
Unrealized gains (losses) on marketable investment securities	(59)	7	111
Accrued acquisition of equipment	293	428	96
Accrued acquisition of inventory	7,279	602	0
Noncash principal payments	32,381	26,915	52,050
Conversion of 5.75% convertible notes	$ 16,535	$ 0	$ 0