Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Summary of the Change in the Company's Outstanding Shares of Common Stock

The following is a summary of the change in the Company’s outstanding shares of voting common stock:

	Year Ended December 31,
	2017			2016			2015
	(In thousands)
Outstanding shares of voting common stock at the beginning of year		37,544			37,409			37,319
Exercise of stock options		262			181			183
Issuance of restricted stock, net of shares withheld for    withholding tax payments and cancellations		39			104			178
Repurchases		(224	)		(150	)		(271	)
Outstanding shares of voting common stock at the end of year		37,621			37,544			37,409