Summary of Significant Accounting Principles - Customers with Revenues Greater than 10% (Detail) - Jun. 30, 2014 - Sales [Member] - Customer Concentration Risk [Member]	Total	Total
Caterpillar Inc. [Member]
Revenue, Major Customer [Line Items]
Customers with revenues greater than 10%	12.40%	13.30%
Komatsu Ltd. [Member]
Revenue, Major Customer [Line Items]
Customers with revenues greater than 10%	10.20%	11.10%