Shareholders' Equity - Shares Outstanding (Details) - $ / shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock (in shares)	14,592,888		14,592,888
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	71,675,379
Issuance (repurchased) pursuant to benefit plans (in shares)	458,855	123,216
Restricted stock forfeited and withheld for taxes (in shares)	(124,440)	(60,081)
Stock options exercised (in shares)	0	8,438
Class B common stock converted to Class A common stock (in shares)	3,485,215	0
Shares issued at end of period (in shares)	75,546,691	71,746,952
Treasury stock (in shares)	14,592,888	14,592,888
Total shares outstanding (in shares)	60,953,803	57,154,064
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)	23,793,669	23,793,669
Issuance (repurchased) pursuant to benefit plans (in shares)	0	0
Restricted stock forfeited and withheld for taxes (in shares)	0	0
Stock options exercised (in shares)	0	0
Class B common stock converted to Class A common stock (in shares)	(3,485,215)	0
Shares issued at end of period (in shares)	20,308,454	23,793,669
Treasury stock (in shares)	0	0
Total shares outstanding (in shares)	20,308,454	23,793,669