Acquisitions - Fair Values of Assets Acquired and Liabilities Assumed at Date of Closing - SAT (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 26, 2014
Business Acquisition [Line Items]
Goodwill	$ 170,153	$ 220,163	$ 165,861
SAT Technology, Inc. ("SAT") [Member]
Business Acquisition [Line Items]
Current assets				$ 1,679
Property and equipment				10
Goodwill				1,733
Intangible – finite life				840
Intangible – indefinite life				260
Total assets acquired				4,522
Current liabilities assumed				(1,847)
Deferred tax liabilities				(275)
Net assets acquired				$ 2,400