Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accounts receivable, allowance for doubtful accounts	$ 2,452	$ 1,942
Property and equipment depreciation	$ 87,577	$ 84,941
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	22,250,000	22,163,000
Treasury stock, shares	3,392,000	2,463,000
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