Income taxes - Summary of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
State			$ 1
Foreign		$ 60
Federal			(9,390)
State			(2,408)
Total income tax expense (benefit)	$ (11,797)	$ 60	$ (11,797)