Intangible Assets and Goodwill - Finite Lived Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Intangible assets that are subject to amortization
Cost	$ 1,082,600	$ 1,082,600
Accumulated Amortization	(99,407)	(24,852)
Net Carrying Amount	$ 983,193	$ 1,057,748
Customer relationships
Intangible assets that are subject to amortization
Amortization Period	12 years	12 years
Cost	$ 928,200	$ 928,200
Accumulated Amortization	(77,350)	(19,338)
Net Carrying Amount	$ 850,850	$ 908,862
Content and data
Intangible assets that are subject to amortization
Amortization Period	7 years	7 years
Cost	$ 154,400	$ 154,400
Accumulated Amortization	(22,057)	(5,514)
Net Carrying Amount	$ 132,343	$ 148,886