Intangible Assets - Changes in Goodwill, Customer Relationships and Trademarks (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 120,343
Balance at end of period	120,343
Finite-lived Intangible Assets [Roll Forward]
Balance at end of period	41,285
Customer Relationships— Acquired & Non-Compete Agreements
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	36,194
Amortization	(9,799)
Balance at end of period	26,395
Customer Relationships— Other
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	6,865
Additions	6,913
Amortization	(4,835)
Balance at end of period	8,943
Trademarks
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	7,287
Amortization	(1,340)
Balance at end of period	$ 5,947