Investments - Components of assets and liabilities (Details 3) (EAM Trust, USD $) In Thousands, unless otherwise specified	Jul. 31, 2014		Apr. 30, 2014
EAM Trust
Schedule of Investments [Line Items]
EAM's total assets	$ 59,931		$ 59,965
EAM's total liabilities	(3,054)	[1]	(3,158)	[1]
EAM's total equity	$ 56,877		$ 56,807

[1] At July 31, 2014 and April 30, 2014, EAM's total liabilities included a payable to VLI for its accrued non-voting revenues and non-voting profits interests of $2,003,000 and $1,887,000, respectively.