Share-Based Compensation, Period Costs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based compensation expense
Share-based compensation	$ 7,624	$ 7,097	$ 7,592
Less income tax effect	(2,613)	(2,314)	(2,583)
Net Share-based Compensation Expense	5,011	4,783	5,009
Cost of revenues [Member]
Share-based compensation expense
Share-based compensation	997	1,060	1,178
Research and development [Member]
Share-based compensation expense
Share-based compensation	3,197	2,875	3,132
Selling, general and administrative [Member]
Share-based compensation expense
Share-based compensation	$ 3,430	$ 3,162	$ 3,282