Acquisitions - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets acquired:
Goodwill	$ 484,941	$ 452,728
2018 Acquisitions
Assets acquired:
Cash	672
Accounts receivable	19,450
Other receivables	1,470
Inventories	11,558
Prepaid and other current assets	73
Property and equipment	9,843
Goodwill	34,314
Intangible assets	25,812
Other assets	74
Total assets acquired	103,266
Liabilities assumed:
Accounts payable	(7,162)
Deferred tax liability	(1,019)
Accrued expenses and other current liabilities	(936)
Total liabilities assumed	(9,117)
Total net assets acquired	$ 94,149
2017 Acquisitions
Assets acquired:
Cash		1,593
Accounts receivable		18,118
Other receivables		1,457
Inventories		9,207
Prepaid and other current assets		300
Property and equipment		8,799
Goodwill		26,096
Intangible assets		18,773
Other assets		66
Total assets acquired		84,409
Liabilities assumed:
Accounts payable		(8,474)
Accrued expenses and other current liabilities		(1,304)
Long-term liabilities		0
Total liabilities assumed		(9,778)
Total net assets acquired		$ 74,631