Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accumulated amortization of intangible assets	$ 18,568	$ 17,135
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, par value (in dollars per share)	$ 0.025	$ 0.025
Common stock, shares authorized	140,000,000	140,000,000
Common stock, shares issued	85,563,377	90,849,428
Common stock, shares outstanding	85,563,377	90,849,428