Shareholders' Equity (Narrative and Dividends) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) vote stock_class $ / shares shares	Dec. 31, 2020 $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Jul. 30, 2018 USD ($)
Shareholders' Equity [Line Items]
Number of classes of common stock | stock_class	3
Preferred stock, authorized shares	500,000	500,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Preferred stock, issued shares	0	0
Employee stock ownership plan contribution expense | $	$ 0		$ 0
Cash dividend declared (USD per share) | $ / shares		$ 0.15	$ 0.15
Common Class A
Shareholders' Equity [Line Items]
Number of votes | vote	1
Common stock, authorized shares	105,000,000.0	105,000,000.0
Share repurchase program, authorized amount | $				$ 100,000,000.0
Shares repurchased (in shares)	0		0
Remaining authorized repurchases | $	$ 100,000,000.0
Common Class B
Shareholders' Equity [Line Items]
Number of votes | vote	10
Common stock, authorized shares	80,000,000.0	80,000,000.0
Common Class C
Shareholders' Equity [Line Items]
Number of votes | vote	10
Common stock, authorized shares	20,000,000.0	20,000,000.0