Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Weighted Average Number of Shares

The following is a reconciliation between basic and diluted weighted average shares outstanding:

(In thousands)	Years Ended December 31,
	2017	2016	2015
Basic weighted average shares outstanding	64,905	71,746	72,420
Effect of dilution:
Stock options	1	13	148
Restricted stock units	719	651	622
Diluted weighted average shares outstanding	65,625	72,410	73,190

Schedule of Stock by Class

	Shares Outstanding
(In thousands)	Class A  Common Stock		Class B  Common Stock
Balance at December 31, 2014	60,553		11,484
Employee and non-employee director stock transactions*	357		—
Balance at December 31, 2015	60,910		11,484
Share repurchases	(4,120	)	—
Employee and non-employee director stock transactions*	289		—
Balance at December 31, 2016	57,079		11,484
Share repurchases	(7,790	)	—
Employee and non-employee director stock transactions*	312		—
Balance at December 31, 2017	49,601		11,484

*Reflects common stock activity in connection with restricted stock units and stock options granted to employees, as well as in connection with the fulfillment of employees' statutory tax withholding obligations for applicable income and other employment taxes and forfeited employee restricted stock units.