Shareholders' Equity - Shares Outstanding (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock, shares authorized (in shares)	50,000,000		50,000,000
Preferred stock, par value (in dollars per share)	$ 0.01		$ 0.01
Preferred stock, shares issued (in shares)	0		0
Preferred stock, shares outstanding (in shares)	0		0
Class A
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	175,000,000		175,000,000
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued at beginning of period (in shares)	75,714,163	71,727,061
Issued pursuant to benefit plans (in shares)	942,957	605,163
Withheld for taxes pursuant to benefit plans (in shares)	(302,066)	(124,667)
Class B common stock converted to Class A common stock (in shares)	20,308,454	3,485,215
Shares issued at end of period (in shares)	96,663,508	75,692,772
Treasury stock (in shares)	14,592,888	14,592,888	14,592,888
Total shares outstanding (in shares)	82,070,620	61,099,884
Class B
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	25,000,000		25,000,000
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued at beginning of period (in shares)	20,308,454	23,793,669
Issued pursuant to benefit plans (in shares)	0	0
Withheld for taxes pursuant to benefit plans (in shares)	0	0
Class B common stock converted to Class A common stock (in shares)	(20,308,454)	(3,485,215)
Shares issued at end of period (in shares)	0	20,308,454
Treasury stock (in shares)	0	0
Total shares outstanding (in shares)	0	20,308,454