Contracts in Progress and Advance Billings on Contracts - Components of Contracts in Progress and Advance Billings on Contracts (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Contractors [Abstract]
Costs incurred less costs of revenue recognized	$ 160,306	$ 90,191
Revenues recognized less billings to customers	220,450	267,426
Contracts in Progress	380,756	357,617
Billings to customers less revenue recognized	514,089	578,896
Costs incurred less costs of revenue recognized	(352,085)	(379,031)
Advance Billings on Contracts	$ 162,004	$ 199,865