Prepaid expenses and other assets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Prepaid expenses and other assets
Prepaid insurance	$ 537,000	$ 687,000
Prepaid contractor fees and vendor advances	230,000	193,000
Taxes receivable	86,000	96,000
Recoupable deposits and other	104,000	115,000
Prepaid expenses and other assets	957,000	1,091,000
Prepaid insurance included in non-current assets		$ 30,000