Goodwill - Goodwill Activity (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, beginning of period		$ 9,835,400		$ 9,835,400	$ 9,835,400	$ 9,835,400
Accumulated impairment losses, beginning of period		(5,322,104)		(5,322,104)	(4,852,104)	(4,852,104)
Goodwill, net, beginning of period		4,513,296		4,513,296	4,983,296	4,983,296
Impairment losses	$ 0	$ (2,200,000)	$ 0	(2,185,000)	$ 0	(470,000)
Goodwill, end of period	9,835,400			9,835,400		9,835,400
Accumulated impairment losses, end of period	(7,507,104)			(7,507,104)		(5,322,104)
Goodwill, net, end of period	$ 2,328,296			$ 2,328,296		$ 4,513,296