Consolidated Statements of Stockholders' Equity - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	Accumulated Deficit [Member]
Balance at at Dec. 31, 2016	$ 331,902
Balance at (in shares) at Dec. 31, 2016	59,461,291
Stock-based compensation plans
Total comprehensive income (loss)	$ 11,296	$ 9,988
Balance at at Mar. 31, 2017	$ 341,083
Balance at (in shares) at Mar. 31, 2017	59,563,749