Shareholders' Equity - Shares Outstanding (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 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	$ 0.01
Preferred stock, shares issued (in shares)	0	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)	450,175	120,622
Restricted stock forfeited and withheld for taxes (in shares)	(119,644)	(54,293)
Stock options exercised (in shares)	0	8,438
Shares issued at end of period (in shares)	72,057,592	71,750,146
Treasury stock (in shares)	14,592,888	14,592,888
Total shares outstanding (in shares)	57,464,704	57,157,258
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
Shares issued at end of period (in shares)	23,793,669	23,793,669
Treasury stock (in shares)	0	0
Total shares outstanding (in shares)	23,793,669	23,793,669