1. Fair value of financial assets and liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	$ 19,297	$ 11,921	$ 5,276
Fair Value Inputs Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	0		0
Fair Value Inputs Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	0		0
Fair Value Inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	19,297		5,276
Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	$ 19,297