Consolidated Statement of Shareholders' Equity (Unaudited) - 9 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2016	95,966,852			12,414,078
Balance at Dec. 31, 2016	$ 959	$ 345,025	$ 326,110	$ (115,484)	$ 556,610
Net income			14,331		14,331
Stock-based compensation expense		16,761			$ 16,761
Exercise of stock options (in shares)	162,861				173,539
Exercise of stock options	$ 2	2,578			$ 2,580
Vesting of restricted stock units, net of shares withheld for employee tax (in shares)	363,095
Vesting of restricted stock units, net of shares withheld for employee tax	$ 4	(2,902)			(2,898)
Balance (in shares) at Sep. 30, 2017	96,492,808			12,414,078
Balance at Sep. 30, 2017	$ 965	$ 361,462	$ 340,441	$ (115,484)	$ 587,384