Stockholders' Equity, Stock Repurchase Program, Dividends and Shelf Registration (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended						9 Months Ended
	Mar. 11, 2020	Sep. 16, 2019	Apr. 16, 2019	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Aug. 04, 2020	Mar. 18, 2020	May 31, 2019	Apr. 23, 2018
Stock Repurchase Program [Abstract]
Incremental Class A shares authorized to buyback (in shares)														1,212,759
Dividends [Abstract]
Dividends declared (in dollars per share)				$ 0.02	$ 0.02	$ 0.02	$ 0.02	$ 0.02	$ 0.02
Shelf Registration [Abstract]
Maximum amount of debt and equity to be issued under shelf registration															$ 500
Class A Stock [Member]
Stock Repurchase Program [Abstract]
Incremental Class A shares authorized to buyback (in shares)												3,000,000
Dividends [Abstract]
Dividends declared (in dollars per share)				$ 0.02			$ 0.02			$ 0.06	$ 0.06
Class A Stock [Member] | Stock Repurchase Program [Member]
Stock Repurchase Program [Abstract]
Stock repurchase authorized, amount													$ 30
Shares repurchased (in shares)		70,000	1,200,000	133,383			123,743			254,180	397,499
Average price per share of repurchased shares (in dollars per share)		$ 20.07	$ 21.00	$ 12.26			$ 19.26			$ 13.19	$ 19.46
Aggregate purchase price	$ 30
Aggregate number of shares offered to be purchased (in shares)	2,000,000			2,916,775						2,916,775
Class A Stock [Member] | Stock Repurchase Program [Member] | Minimum [Member]
Stock Repurchase Program [Abstract]
Average price per share of repurchased shares (in dollars per share)	$ 15.00
Class A Stock [Member] | Stock Repurchase Program [Member] | Maximum [Member]
Stock Repurchase Program [Abstract]
Average price per share of repurchased shares (in dollars per share)	$ 17.00
Class B Stock [Member]
Dividends [Abstract]
Dividends declared (in dollars per share)				$ 0.02			$ 0.02			$ 0.06	$ 0.06