Fair Value Measurement (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Liabilities:
Buffalo liability	$ 9,200
Grandhaven option	4,060	4,060
Derivative warrant liability	4,505
Recurring | Level 3
Liabilities:
Buffalo liability	9,200
Grandhaven option	4,060	4,060
Derivative warrant liability	4,505
Total liabilities	17,765	4,060
Recurring | Total
Liabilities:
Buffalo liability	9,200
Grandhaven option	4,060	4,060
Derivative warrant liability	4,505
Total liabilities	$ 17,765	$ 4,060