Organization and basis of presentation (Details)	3 Months Ended
	Mar. 31, 2013
Maximum [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	10 years
Minimum [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	5 years
Machinery and laboratory equipment [Member] | Maximum [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	5 years
Machinery and laboratory equipment [Member] | Minimum [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	3 years
Instruments [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	4 years
Office equipment [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Expected useful lives of these assets	5 years
Leasehold improvements [Member]
Estimated useful lives of Property, equipment and leasehold improvements
Leasehold improvements	Over the shorter of the remaining life of the lease or the useful economic life of the asset