Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 3,019	$ 3,260
Accumulated depreciation	319,769	245,629
Accumulated amortization on other intangible assets	$ 29,515	$ 20,545
Par value per share	$ 0.01	$ 0.01
Common stock shares authorized	100,000	100,000
Common stock shares issued	44,863	44,689
Treasury Stock, Shares	931	862