Basis of Presentation and Significant Accounting Policies - Components of Contracts in Progress and Advance Billings on Contracts (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Contractors [Abstract]
Costs incurred less costs of revenue recognized	$ 103,467	$ 65,113
Revenues recognized less billings to customers	233,453	360,873
Contracts in Progress	336,920	425,986
Billings to customers less revenue recognized	680,962	466,205
Costs incurred less costs of revenue recognized	(480,704)	(187,276)
Advance Billings on Contracts	$ 200,258	$ 278,929