CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,306	$ 1,409
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 96,554	$ 95,083
Preferred stock, shares issued	0	0
Shares to be issued, shares	0	0
Common Class A
Common stock, shares issued	49,986,705	49,680,109
Common stock, shares outstanding	49,986,705	49,680,109
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Common Class B
Common stock, shares issued	3,755	3,755
Common stock, shares outstanding	3,755	3,755