Share-Based Payments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Total stock-based compensation expense	$ 739	$ 1,014
General and Administrative Expense [Member]
Total stock-based compensation expense	570	916
Selling and Marketing Expense [Member]
Total stock-based compensation expense	82	74
Research and Development Expense [Member]
Total stock-based compensation expense	24	24
Translational Oncology Solutions Cost Of Sales [Member]
Total stock-based compensation expense	8	0
Personalized Oncology Solutions Cost Of Sales [Member]
Total stock-based compensation expense	$ 55	$ 0