Share-Based Payments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Stock-based compensation expense	$ 552	$ 739
General and Administrative Expense [Member]
Stock-based compensation expense	419	570
Selling and Marketing Expense [Member]
Stock-based compensation expense	63	82
Research and Development Expense [Member]
Stock-based compensation expense	13	24
Translational Oncology Solutions Cost of Sales [Member]
Stock-based compensation expense	8	8
Personalized Oncology Solutions Cost of Sales [Member]
Stock-based compensation expense	$ 49	$ 55