Basis of Presentation - Customers with Revenues Greater than 10% (Detail) (Sales [Member])	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Caterpillar Inc. [Member]
Revenue, Major Customer [Line Items]
Customers with revenues greater than 10%	14.40%	25.40%
Komatsu Ltd. [Member]
Revenue, Major Customer [Line Items]
Customers with revenues greater than 10%	12.10%	13.20%