Shareholders' Equity (Shareholders' Equity Narrative) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) vote stock_class $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Jul. 30, 2018 USD ($)
Schedule of Shareholders' Equity Activity [Line Items]
Number of classes of common stock | stock_class	3
Preferred stock authorized (in shares) | shares	500,000	500,000
Preferred stock, par value (in dollars per shares) | $ / shares	$ 0.01	$ 0.01
Preferred stock issued | shares	0	0
Stock repurchase program, authorized amount (up to)			$ 100.0
Common Class A
Schedule of Shareholders' Equity Activity [Line Items]
Number of votes per share | vote	1
Number of shares repurchased | shares	2,852,501	3,093,662
Remaining authorized repurchase amount	$ 77.5
Stock repurchased during period, value	12.6	$ 9.9
Stock repurchased during period, value, including commissions	$ 12.6	$ 10.0
Average cost per share (in dollars per share) | $ / shares	$ 4.40	$ 3.21
Common Class B
Schedule of Shareholders' Equity Activity [Line Items]
Number of votes per share | vote	10
Common Class C
Schedule of Shareholders' Equity Activity [Line Items]
Number of votes per share | vote	10