Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts	$ 1,297	$ 1,220
Property and equipment depreciation	$ 90,938	$ 88,859
Preferred stock, par value	$ 0.10	$ 0.10
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	22,443,000	22,326,000
Treasury stock, shares	3,653,000	3,653,000
Common Class B [Member]
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	3,175,000	3,175,000
Common stock, shares issued	0	0