Stock Repurchase Program Stock Repurchase Program (Details) - Class A Common Stock [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Dec. 31, 2019	Oct. 03, 2019	Aug. 29, 2019	Aug. 28, 2019	Dec. 07, 2017
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 150,000
Stock Repurchase Program, Increase in Authorized Amount			$ 300,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 185,997		$ 436,165	$ 136,165
Tender Offer [Member]
Equity, Class of Treasury Stock [Line Items]
Modified Dutch Auction Tender Offer Price Per Share		$ 16.70
Tender Offer Share Amount		14,980
Share Repurchase Obligation excluding Cash Payments		$ 250,168