Acquisitions - Assets (Liabilities) Acquired (Assumed) at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Tangible assets (liabilities) acquired (assumed):
Goodwill		$ 386,945	$ 386,941
Cash paid for acquisitions, net of cash acquired	$ 21,169
2019 Acquisitions
Tangible assets (liabilities) acquired (assumed):
Inventories, net	9,096
Prepaid expenses and other assets	87
Property and equipment, net	105
Accrued liabilities	(100)
Total tangible net assets acquired	9,188
Goodwill	11,981
Purchase Price	21,169
Cash paid for acquisitions, net of cash acquired	21,169
Inventory purchases financed via floor plan	(8,416)
Cash payment net of floor plan financing	$ 12,753