Acquisition - Additional Information (Detail) - Ingalls Engineering Company, Inc., [Member] - USD ($) $ in Millions		6 Months Ended
	Jan. 06, 2017	Jul. 01, 2017
Business Acquisition [Line Items]
Business acquisition date		Jan. 06, 2017
Business acquisition, total purchase price consideration	$ 4.8
Business acquisition, portion of purchase consideration paid in cash	3.1
Business acquisition, estimated contingent payments	1.7
Business acquisition of goodwill and other intangible assets	2.9
Business acquisition of other net assets	$ 1.9