Investments - Selective Unaudited Financial Information for Equity Method Investment (Details) - Shred-it Partnership - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Assets
Current assets	$ 150,792	$ 108,377
Non-current assets	968,956	924,196
Liabilities
Current liabilities	73,971	57,241
Non-current liabilities	532,673	$ 427,569
Summary Income Statement Information
Net sales	695,628
Gross profit	432,532
Net income	$ 10,385