Net Income Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Income Per Common Share
Number of outstanding options not included in computation of Diluted EPS (in shares)	6,000	1,560,000
Numerator
Net income	$ 27,092	$ 9,620
Denominator
Weighted average number of common shares outstanding	51,218,000	51,457,000
Effect of outstanding share-based awards	796,000	935,000
Weighted average number of shares for diluted net income per common share	52,014,000	52,392,000
Basic earnings per share (in dollars per share)	$ 0.53	$ 0.19
Diluted earnings per share (in dollars per share)	$ 0.52	$ 0.18