Shareholders' Equity - Shares Outstanding (Details) - $ / shares	6 Months Ended
	Jun. 30, 2021	Jun. 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)		71,727,061
Issued pursuant to benefit plans (in shares)	790,467	458,855
Withheld for taxes pursuant to benefit plans (in shares)	(249,015)	(124,440)
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)		75,546,691
Treasury stock (in shares)	14,592,888	14,592,888	14,592,888
Total shares outstanding (in shares)	81,971,181	60,953,803
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)		20,308,454
Treasury stock (in shares)	0	0
Total shares outstanding (in shares)	0	20,308,454