Acquisitions - Fair Values of Assets Acquired and Liabilities Assumed at Date of Closing - Zhongli (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 15, 2014
Business Acquisition [Line Items]
Goodwill	$ 170,153	$ 220,163	$ 165,861
Zhongli [Member]
Business Acquisition [Line Items]
Current assets (including cash of $1,025)				$ 16,223
Property and equipment				1,477
Goodwill				4,752
Intangible – finite life				4,262
Intangible – indefinite life				960
Total assets acquired				27,674
Current liabilities assumed				(1,840)
Deferred tax liabilities				(1,739)
Net assets acquired				$ 24,095