Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Accumulated impairment loss	$ 8,300		$ 8,300		$ 8,300
Aggregate amortization expense	14,900	$ 10,400	29,700	$ 18,900
Intangible asset impairment charge	$ 548	$ 0	$ 548	$ 0