Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets acquired:
Goodwill	$ 458,472	$ 437,935
Series of Individually Immaterial Business Acquisitions
Assets acquired:
Cash	1,511
Accounts receivable	17,354
Other receivables	1,223
Inventories	10,594
Prepaid and other current assets	292
Property and equipment	8,497
Goodwill	26,279
Intangible assets	17,567
Other assets	23
Total assets acquired	83,340
Liabilities assumed:
Accounts payable	(7,405)
Accrued expenses and other current liabilities	(1,067)
Total liabilities assumed	(8,472)
Total net assets acquired	$ 74,868