Acquisitions (Contingent purchase price liability) - Additional Information (Detail) $ in Millions	Jun. 30, 2015 USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	$ 4.2
Contingent Purchase Price Liability Current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	1.6
Contingent Purchase Price Liability Non-current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	$ 2.6