Segment Information - Schedule of Fixed Assets, Goodwill and Intangibles, Net (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Long-lived Assets	$ 88,189				$ 90,306				$ 88,189	$ 90,306
Intangible Assets, Net (Including Goodwill)	808,720				906,540				808,720	906,540
Revenue	393,662	$ 375,830	$ 379,743	$ 326,968	402,747	$ 375,800	$ 390,532	$ 344,700	1,476,203	1,513,779	$ 1,385,785
United States
Segment Reporting Information [Line Items]
Long-lived Assets	76,781				77,163				76,781	77,163
Intangible Assets, Net (Including Goodwill)	679,344				706,241				679,344	706,241
Revenue									1,153,192	1,172,364	1,103,714
Canada
Segment Reporting Information [Line Items]
Long-lived Assets	4,779				5,638				4,779	5,638
Intangible Assets, Net (Including Goodwill)	61,748				127,014				61,748	127,014
Revenue									124,000	123,092	124,101
Other Geographical Location
Segment Reporting Information [Line Items]
Long-lived Assets	6,629				7,505				6,629	7,505
Intangible Assets, Net (Including Goodwill)	$ 67,628				$ 73,285				67,628	73,285
Revenue									$ 199,011	$ 218,323	$ 157,970