Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 VS [Member]	Mar. 31, 2014 VS [Member]	Jun. 30, 2014 VS [Member] Adjustments to Fair Value [Member]	Jun. 30, 2014 RFK [Member]	Jun. 20, 2014 RFK [Member]
Business Acquisition [Line Items]
Current assets			$ 1,407	$ 1,263	$ 144		$ 3,940
Property, plant, and equipment			7,066	6,902	164		7,684
Intangible assets subject to amortization			75	75			1,740
Goodwill	9,384	8,624		244	(244)	732	732
Total assets acquired			8,548	8,484	64		14,096
Current liabilities			2,968	2,904	64		1,781
Total liabilities assumed			2,968	2,904	64		1,781
Net asset acquired			$ 5,580	$ 5,580			$ 12,315