ACQUISITIONS Identifiable Intangible Assets and Estimated Useful Lives (Detail) - USD ($) $ in Thousands	Jan. 01, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill		$ 1,108,337	$ 825,038	$ 829,073
Freightquote
Business Acquisition [Line Items]
Cash and cash equivalents	$ 29,302
Receivables	56,228
Other current assets	2,395
Property and equipment	43,687
Identifiable intangible assets	37,800
Goodwill	287,220
Trademarks	8,600
Other noncurrent assets	3,421
Total assets	468,653
Accounts payable	(44,622)
Accrued expenses	(5,485)
Other liabilities	(19,939)
Net assets acquired	398,607
Total identifiable intangible assets	$ 37,800
Customer Relationships | Freightquote
Business Acquisition [Line Items]
Estimated Life (years)	5 years
Finite-lived intangible assets acquired	$ 37,500
Noncompete Agreements | Freightquote
Business Acquisition [Line Items]
Estimated Life (years)	5 years
Finite-lived intangible assets acquired	$ 300