Condensed Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Preferred Stock	Common Stock USD ($)	Additional Paid-in Capital USD ($)	Retained (Deficit) Earnings USD ($)	Accumulated Other Comprehensive (Loss) Income USD ($)	Total USD ($)
Balance at Dec. 31, 2013		$ 775	$ 887,556	$ (130,314)	$ 383	$ 758,400
Balance (in shares) at Dec. 31, 2013	8,624	77,788,393
Increase (Decrease) in Shareholders' Equity
Share-based compensation arrangements, net of tax benefits of $7,752 and $6,379 for the three months ended March 31, 2014 and 2015 respectively		5	15,907			15,912
Share-based compensation arrangements (in shares)		766,722
Foreign currency translation adjustment					(700)	(700)
Net income				4,537		4,537
Balance at Mar. 31, 2014		780	903,463	(125,777)	(317)	778,149
Balance (in shares) at Mar. 31, 2014	8,624	78,555,115
Balance at Dec. 31, 2014		786	918,370	(363,388)	(1,282)	554,486
Balance (in shares) at Dec. 31, 2014	8,624	79,161,817
Increase (Decrease) in Shareholders' Equity
Share-based compensation arrangements, net of tax benefits of $7,752 and $6,379 for the three months ended March 31, 2014 and 2015 respectively		5	11,228			11,233
Share-based compensation arrangements (in shares)		543,816
Foreign currency translation adjustment					(1,716)	(1,716)
Net income				10,996		10,996
Balance at Mar. 31, 2015		$ 791	$ 929,598	$ (352,392)	$ (2,998)	$ 574,999
Balance (in shares) at Mar. 31, 2015	8,624	79,705,633