Japan pension plans (Details)	1 Months Ended	2 Months Ended	3 Months Ended	9 Months Ended
	May. 31, 2014 USD ($)	Feb. 28, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 29, 2013 item
Compensation And Retirement Disclosure [Abstract]
Number of Defined Benefit Pension Plans | item						2
Employer contributions	$ 2,000,000	$ 15,000
Conversion of plan, proceed from LAPIS				$ 300,000
Defined Benefit Plan, Curtailments			$ 100,000
Pension liability				5,100,000	$ 5,100,000
Pension liability included in accrued and other current liabilities				$ 100,000	$ 100,000