Share-Based Compensation - Share based Compensation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of share-based compensation
Share based compensation	$ 8,342	$ 5,827	$ 7,187
Incentive Stock Options
Summary of share-based compensation
Share based compensation	573	310	786
Non-Qualified Stock Options
Summary of share-based compensation
Share based compensation	171	222	660
Restricted stock
Summary of share-based compensation
Share based compensation	4,504	3,684	5,464
Restricted stock units
Summary of share-based compensation
Share based compensation	$ 3,094	$ 1,611	$ 277