Income taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current Income Tax Expense (Benefit) [Abstract]
Federal	$ 0	$ 0	$ 0
State and local	53	(107)	29
Foreign	(160)	(252)	(262)
Total current income tax (expense)/benefit	(107)	(359)	(233)
Deferred Income Tax Expense (Benefit) [Abstract]
Federal	20	(1,061)	(1,149)
State and local	3	(182)	(198)
Total deferred income tax (expense)	23	(1,243)	(1,347)
Income tax provision	$ (84)	$ (1,602)	$ (1,580)