Supplemental Cash Flows Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Supplemental disclosure of cash flow data:
Interest paid	$ 21,001	$ 28,710
Income taxes paid	10,081	3,474
Supplemental disclosure of noncash investing and financing activities:
Contingent consideration payable	337	5,900
Contingent consideration settled with the issuance of Class A common stock		$ 771
Exchange of Class C and Class D common stock for Class A common stock	17,758
Secondary Offering	$ 171,300