Share-Based Compensation -Summary of Additional Information on Stock Options (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of additional information pertaining to stock options
Total intrinsic value of stock options outstanding	$ 2,723	$ 2,329	$ 0
Total intrinsic value of stock options exercised	1,611	296	325
Fair value of stock options vested	532	539	682
Cash received from the exercise of stock options	777	248	296
Tax deficiencies from share-based compensation	$ 404	$ 96	$ (325)