Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Current assets:
Cash and cash equivalents	$ 94,027	$ 50,165	$ 67,630
Restricted cash		200
Accounts receivable, net	7,234	6,823
Inventory	5,757	6,425
Prepaid expenses and other assets	4,398	2,755
Total current assets	111,416	66,368
Restricted cash, non-current	192	192
Property and equipment, net	5,123	4,537
In-process research and development	2,128	2,399
Goodwill	44	50
Other intangible assets, net	250	273
Other assets	24	30
Total assets	119,177	73,849
Current liabilities:
Accounts payable	2,695	2,368
Accrued liabilities	4,622	7,070
Deferred income	1,886	1,993
Current portion of loans payable	131	137
Total current liabilities	9,334	11,568
Long-term portion of loans payable	418	454
Contingent purchase price consideration	1,126	1,218
Total liabilities	10,878	13,240
Commitments and contingencies (Note 2)
Shareholders’ equity:
Ordinary shares, £0.006705 nominal value; 36,183,293 shares authorized at March 31, 2015 and December 31, 2014, and 22,513,782 and 17,614,650 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	242	192
Additional paid-in capital	241,416	186,816
Accumulated deficit	(128,140)	(121,829)
Accumulated other comprehensive loss	(5,219)	(4,570)
Total shareholders’ equity	108,299	60,609
Total liabilities and shareholders’ equity	$ 119,177	$ 73,849